Testing And Adjusting



NOTE: For Specifications with illustrations, make reference to ENGINE SPECIFICATIONS FOR D349 VEHICULAR ENGINE, Form No. SENR7174. If the Specifications in Form SENR7174 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications in the book with the latest date.


Troubleshooting can be difficult. On the following pages there is a list of possible problems. To make a repair to a problem, make reference to the cause and correction.

This list of problems, possible causes, and remedy, will only give an indication of where a possible problem can be, and what repairs are needed. Normally, more or other repair work is needed beyond the recommendations in the list. Remember that a problem is not normally caused only by one part, but by the relation of one part with other parts. This list can not give all possible problems and corrections. The serviceman must find the problem and its source, then make the necessary repairs.

1. Engine Fails to Start
2. Misfiring
3. Stalls at Low Speed
4. Erratic Engine Speed
5. Low Power
6. Excessive Vibration
7. Heavy Combustion Knock
8. Valve Train Clicking Noise
9. Oil in Coolant
10. Mechanical Knock
11. Excessive Fuel Consumption
12. Loud Valve Train Noise
13. Excessive Valve Lash
14. Valve Spring Retainer Free
15. Slobber
16. Valve Lash Close-up
17. Premature Engine Wear
18. Coolant in Engine Lubricating Oil
19. Excessive Black or Gray Smoke
20. Excessive White or Blue Smoke
21. Low Engine Oil Pressure
22. High Lubricating Oil Consumption
23. Abnormal Engine Coolant Temperature
24. Alternator Fails to Charge
25. Alternator Charging Rate Low or Unsteady
26. Alternator Charging Rate Excessive
27. Noisy Alternator
28. High Exhaust Temperature

Fuel System

Difficulty within the fuel system can be caused by lack of fuel or too much fuel for proper combustion.

Many times, the fuel system is blamed when the fault lies elsewhere, especially when smoky exhaust is the problem. Smoky exhaust can be the result of a faulty fuel injection valve, but it can also be caused by lack of air for complete combustion, overloading at high altitude, excessive oil burning or lack of compression. See the topic, AIR INDUCTION AND EXHAUST SYSTEM for conditions that may cause lack of horsepower.

Visual Inspection

1. Observe the fuel pressure gauge reading. Lack of pressure usually indicates difficulty in the supply side of the system.

2. Check the fuel level in the supply tank and the fuel tank cap vent for being plugged. Drain the water and sediment from the tank.

3. Check for leakage in the fuel supply lines and components or for a kinked or restricted supply line.

4. Replace the fuel filter elements.

5. Inspect the fuel bypass valve to see that it moves freely and that dirt is not holding the plunger off its seat. Be certain the spring has proper tension.

6. Bleed the fuel system to remove trapped air.

7. Test the fuel transfer pump.

To test the fuel transfer pump, connect an 8M2743 Pressure Gauge which is part of 7S8875 Hydraulic Test Box in place of the fuel pressure gauge line at the filter housing.

The pressure should be:

Full load ... 30 ± 5 psi(2.11 ± 0.35 kg/cm2)

Low idle ... min. 15 psi(1.05 kg/cm2)

Cranking speed ... 10 to 15 psi(0.7 to 1.05 kg/cm2)

Fuel Injection Service

Always inspect the seats of both the nozzle and the precombustion chamber prior to installing a fuel injection valve. The nozzle assembly should be finger tight on the body. It is important to maintain the nozzle retaining nut torque to 105 ± 5 lb.ft. (14.5 ± 0.7 mkg), refer to SPECIFICATIONS for procedure. Excessive torque will damage the nozzle. Less torque can cause the nozzle case to bulge or split and will allow the nozzle to leak, resulting in fuel dilution of the crankcase oil. Any loose fuel line connections inside the camshaft housings can cause crankcase dilution, and result in low oil pressure, bearing wear, and engine damage.

Testing Fuel Injection Equipment

Before attempting to test a fuel injection pump or valve in an engine that is misfiring or puffing black smoke, make a simple check to determine which cylinder is causing the difficulty. While operating the engine at a speed which makes the defect most pronounced, momentarily loosen a fuel line nut at the fuel injection pump sufficiently to "cut-out" one cylinder. Check all cylinders in the same manner. If, after cutting out a cylinder, there is no noticeable difference in engine operation, or if this action causes puffing of black smoke to cease, the pump and valve for only that cylinder need be tested. Incomplete combustion in this particular cylinder can also be caused by low or no compression (worn or broken rings, leaking or incorrectly adjusted valves) so further testing may be necessary.

Checking Fuel Injection Valves

Examine fuel injection valves for:

1. Excessive carbon on tip of nozzle or in orifice.
2. Erosion of the orifice.
3. Screen plugged with dirt.

The condition of a capsule-type nozzle assembly can be tested on the Caterpillar Diesel Fuel Injection Test Apparatus, and the nozzle leakage rate can be determined.

Checking Fuel Injection Pump Lifter Washer and Pump Plunger

The timing dimension should be checked and adjusted, if necessary, with the fuel injection pump off the engine. If the timing dimension is too small, injection will begin early, and if too great, injection will be late.

When pump plunger wear becomes excessive, the lifter washer may also be worn so it will not make full contact with the end of a new plunger. To avoid rapid wear on the end of the new plunger, replace the lifters having washers showing visible wear.

These are patterns of wear between washer and plungers. Fig. A illustrates the contact surfaces of a new pump plunger and a new lifter washer. In Fig. B the pump plunger and lifter washer have worn considerably. Fig. C shows how the flat end of a new plunger makes poor contact with a worn lifter washer, resulting in rapid wear to both parts.

A pump can maintain a satisfactory discharge rate and yet be unserviceable because of delayed timing resulting from wear on the lower end of the plunger. When testing a pump that has been in use for a long time, check the plunger length with a micrometer. Discard the pump if the plunger measures less than the minimum length (worn) dimension.

Inspect the upper diameter of the plunger for wear. The performance of pumps worn in this manner can be checked as described in the Instructions for Fuel Injection Test Apparatus.

Removing And Installing Fuel Injection Pump Assemblies

1. Remove the timing pin assembly from its storage position and install one of the retaining bolts (head down) through one of the flange holes. Install a nut at the top to hold the bolt in place. The bolt head limits the depth the pin can be inserted into the housing.

2. Insert the pin assembly (1) in the timing hole. Move the governor control or rack linkage back and forth slowly between SHUTOFF and 0, to allow the pin to pass through the notch in the rack. The pin is in place when the head of the inverted bolt touches the fuel pump housing.

1. Timing pin.

NOTE: The fuel pump housing and rack are now ready for installing or removing the fuel injection pump assemblies.

3. With the flat on the pump gear segment and alignment pin visually aligned, install the injection pump assembly into the fuel pump housing and install the pump retaining bolts finger tight. If the injection pump cam lobe is up, use downward pressure (by hand) to push the pump body flush with the fuel injection pump housing. This ensures the gear segment is positioned by the alignment pin during installation. It also prevents sheering the alignment pin while tightening the retaining bolts.

Align the flat on the back of the gear segment with alignment pin (2) located in the top of the lifter assembly as the fuel pump and body are placed into position. This flat and locating pin provide for correct rack tooth and gear segment alignment.

4. Remove the timing pin assembly and place it in the storage position.

Locating Top Center Compression Position For No. 1 Piston

No. 1 piston on the compression stroke at top center (TC) is the reference point for all timing procedures.

Remove the right side valve covers. The four valves at the right front of the engine are the inlet and exhaust valves for No. 1 cylinder.

1. Bolts (three). 2. Drive pinion. 3. Spacer. 4. Timing bolt.

1. Remove drive pinion (2) and spacer (3). Install pinion back into the flywheel housing without spacer.

NOTE: Use wrench (6) and pinion (2) to rotate flywheel.

2. Engage the teeth of pinion (2) with the teeth on the flywheel ring gear. Rotate the flywheel clockwise (as viewed from the flywheel end of the engine) at least 30° beyond the timing bolt hole in the flywheel. Now rotate the flywheel counterclockwise (as viewed from the flywheel end of the engine) until timing bolt can be installed in the flywheel.

NOTE: If timing hole is passed, do not back up, repeat Step 2.

3. Install bolt (4) through hole (5) and into the threaded hole in flywheel.

4. Observe the position of the camshaft drive gears. The dash marks on camshaft drive gears must align, the pointer in the camshaft housing must align with dash marks on gear and camshaft timing pin must fit into camshaft. All four valves for No. 1 cylinder should now be closed. If all valves are not closed, the flywheel must be rotated 360° counterclockwise.

2. Drive pinion. 5. Timing bolt hole. 6. 8H8557 Ratchet Wrench.

Checking Fuel Injection Pump Timing (On Engine)

When checking lifter setting ON ENGINE, check No. 1 lifter only. If setting is incorrect, make adjustments with fuel injection pump housing OFF ENGINE.

Checking With Timing Pins

1. Locate (TC) compression position for No. 1 piston.

2. Remove the speed limiter access plug. Install the 9S8521 Rod and 9S8519 Plug to depress the speed limiter.

3. Remove timing pin assembly from storage location and install it through the timing hole in the fuel injection pump housing. When timing pin fits into the timing slot in the fuel pump camshaft, it must be flush with the top of the fuel pump housing.


NOTE: Move the governor control lever back and forth slowly between SHUTOFF and 0 to allow the pin to first pass through the notch in the rack. The pin can then drop through to engage the slot in the camshaft.

4. If the timing pin fits into the fuel pump camshaft slot, the fuel pump camshaft is correctly timed to the engine crankshaft. If the timing pin does not fit into the camshaft timing slot, one of the following problems has occurred:

a. Timing gear backlash has increased (worn) during machine operation. Adjust the speed sensing, variable timing drive gear.

b. Variable timing unit malfunction. Look for binding flyweights or burr in sliding spline drive.

c. Variable timing drive gear has slipped or was not adjusted correctly.

NOTE: A slight binding of the timing pin during insertion is not cause for adjusting the variable timing drive gear. If the timing pin does not fit, refer to the topic FUEL INJECTION PUMP CAMSHAFT TIMING.

Checking the Timing of the Fuel Injection Pump and the Movement of the Variable Timing Drive Assembly with 1P3500 Injection Timing Group.


Refer to Special Instruction GMG00501 for complete and detailed instructions for the timing light method of checking engine timing and the movement of the variable timing advance.

1. Install the appropriate transducer in the fuel injection line for No. 1 cylinder. Be sure the arrow on the transducer is in the direction of fuel flow.

2. Locate the top center position of No. 1 cylinder. Make reference to Locating Top Center Compression Position For No. 1 Piston.

3. Scribe the damper and install a temporary pointer.

4. Connect the timing light as indicated and run the engine at low idle.


The transducers are designed for operation at no load conditions. Do not operate the engine under full load conditions with a transducer in the fuel line.

5. Put the switch (1) in the "ADV" position and depress the trigger. Aim the flashing timing light at the damper.

6. Align the top center scribe mark with the pointer by adjusting knob (2). Read timing on the top meter scale. The readings should be within 1° of the following values.

USING TIMING LIGHT (Typical Example)
1. Switch. 2. Knob.

7. To check movement of variable timing advance, repeat step (6) at high idle. Make reference to the chart for the correct movement of the variable timing advance.

8. Turn knob (2) past the detent to the "time" position and place switch (1) in the "ADV" position. Observe the mark on the damper for smoothness of advance through the speed range.

Checking With 1P540 Flow Checking Tool Group, 3S2954 Timing Indicator Group And 9M9268 Dial Indicator

Refer to Special Instruction (FM035709) for complete and detailed instructions for the fuel flow method of engine timing.

Travel of piston (6), from point of closing inlet port (5) to top center, can be found by using the 3S2954 Timing Indicator Group. Convert the travel of piston (6) into degrees to determine if engine timing is correct.

1. 3S3263 Adapter. 2. 9M9268 Dial Indicator. 3. 3S3264 Rod. 4. Precombustion chamber. 5. Inlet port. 6. Piston. 7. Crankshaft.

The 1P540 Flow Checking Tool Group is used to pressurize the fuel system. Maintain 10 to 15 psi (0.70 to 1.05 kg/cm2) fuel pressure with the 1P539 Tank Assembly. This can be done with hand pump provided with the tank assembly, or connecting shop air to the tank assembly.

Consult chart to find angle corresponding to indicator reading. At the indicator reading and timing angle specified for this particular engine, fuel flow from the injection pump should be reduced to 12 to 30 drops per minute [point of closing inlet port (5)].

Fuel Injection Pump Camshaft Timing

1. Locate (TC) compression position for No. 1 piston. Refer to the topic LOCATING TOP CENTER COMPRESSION POSITION FOR No. 1 PISTON.

1. 9S8521 Rod. 2. Timing pin. 3. Timing hole. 4. Pin storage hole.

2. Remove the speed limiter access plug. Install the 9S8521 Rod (1) and 9S8519 Plug to depress the speed limiter.

3. Remove the timing pin (2) from the storage hole (4) and install the timing pin in the timing hole (3).

NOTE: Move the governor control lever back and forth slowly between SHUTOFF and 0 to allow the pin to first pass through the slot in the rack. The pin can then drop through to engage the timing hole in the camshaft.

a. If the pin assembly slips into the camshaft slot, and is flush with the top of the housing, the fuel pump camshaft is correctly timed to the crankshaft (No. 1 piston TC COMPRESSION POSITION).

b. If the timing pin will not enter the camshaft slot, loosen the retaining bolts securing the drive gear to the variable timing unit. Rotate the camshaft CLOCKWISE ONLY by turning the retainer with 1/2" square drive until the timing pin engages the camshaft timing slot.

4. With the retainer bolts loose and timing pin installed, rotate the flywheel approximately 30° CLOCKWISE.


5. Finger tighten two of the retainer bolts and rotate the flywheel counterclockwise (30°) to again align the pointer to the flywheel timing mark.

NOTE: As the flywheel is rotated counterclockwise, the drive gear slips yet has the resistive force so backlash is taken up in direction of normal rotation.

6. Remove the fuel injection pump camshaft timing pin. Tighten all retaining bolts and rotate the engine flywheel two complete revolutions (counterclockwise as viewed from the rear). Install the timing pin into the fuel pump camshaft slot. If pin fits, timing is correct. If the pin does not fit, repeat Steps 4, 5 and 6.

NOTE: Be sure the relative position of the drive gear and the variable timing drive unit does not change while tightening the retaining bolts.

7. If timing is correct, tighten all variable timing drive gear retaining bolts to 75 ± 10 lb.ft. (10.4 ± 1.4 mkg) and secure the locks.


NOTE: This timing procedure must be completed accurately so the timing pin fits into the camshaft slot when all backlash is taken up on the drive side of the timing gear teeth. Rotate gears as described.

Fuel Pump Timing Dimension Setting: Off Engine

1. 1P7410 or 1F8747 Timing Plate.
2. 8S2625 Shaft Assembly with key.
3. 1P7415 or 8S2624 Pointer Assembly.
4. 4B4278 Washer.
5. Bolt, 3/8 - 16 in. NC (3/4 in. long). 6F6922 Depth Micrometer.

1. Remove the pump assemblies from the fuel pump housing. Tag the pump assemblies for reinstallation into their respective locations. Keep barrels and plungers in original matched sets and store in a clean covered area. Remove the fuel rack from the front end of the fuel pump housing.

1. 8S2625 Shaft Assembly with key. 2. 1P7415 Pointer Assembly.

2. Remove the variable timing drive from the rear of the fuel pump housing and replace it with shaft assembly (1). Shaft assembly (1) tang must engage the slot in the rear of the fuel pump camshaft.

3. Install pointer assembly (2) on the pump housing. Dowels pressed into the pointer assembly locate the edge of the pointer assembly for correct timing.

4. Install the key in the end of shaft assembly (1). Install timing plate (3) with bolt (5) and washer (4).

2. 1P7415 Pointer Assembly. 3. 1P7410 Timing Plate. 4. Washer. 5. Bolt.

5. Rotate the timing plate CLOCKWISE to align the degree setting with the edge of the pointer assembly, and measure dimension (A), from the top of the pump housing to the top of the spacer, in the lifter assembly for No. 1 cylinder.

6. If dimension (A) is not within the specified limits new lifter assemblies must be installed. Refer to the following chart:

A. Timing dimension at the designated degree setting should be 3.016 ± .002 in. (76.61 ± 0.05 mm). B. Lifter thickness.

NOTE: Do not attempt to remove or replace spacers in lifter assemblies. An improperly staked spacer can cause engine failure.

7. Proceed with setting the remaining lifters being sure the timing pointer is aligned with the correct degree mark on the timing plate for each lifter being checked. Always turn the timing plate clockwise when aligning to the degree setting in the chart.

Governor Adjustments


Only competent personnel should attempt to adjust the low and high idle rpm. The low and high idle rpm, and the rack setting dimensions for this engine, are listed in the RACK SETTING INFORMATION.

1. Install an accurate tachometer to the service meter drive (use 4S6553 Test Kit).

2. Start the engine and move the governor control to HIGH IDLE position. Observe the tachometer reading and compare with the HIGH IDLE value listed in the RACK SETTING INFORMATION.

3. Adjust HIGH IDLE rpm by turning high idle screw (1). After achieving specified rpm, move the governor control to reduce engine speed, then move the linkage to HIGH IDLE and recheck the setting.

4. After setting HIGH IDLE rpm, move the governor linkage to the LOW IDLE position and adjust the LOW IDLE rpm in a similar manner.

1. High idle adjusting screw. 2. Low idle adjusting screw.

Rack Adjustment

9S240 Rack Positioning Tool Group.


Rack settings are carefully set at the factory and should not be changed without specific instructions to do so. An incorrectly adjusted fuel rack affects the operation of the turbocharger.

1. Remove the fuel ratio control. Disconnect the governor control linkage at convenient location so full rack travel can be obtained.

2. Remove speed limiter access plug. Using rod (1) and plug (2), depress the speed limiter plunger. [Tighten plug (2) just enough to impose a clamping action on rod (1)].

1. 9S8521 Rod (for manually depressing speed limiter plunger). 2. 9S8519 Plug (rod guide).

3. Remove the timing pin assembly from its storage position and install one of the retaining bolts (head down) through one of the flange holes. Install a nut at the top to hold the bolt in place. The bolt head limits the depth the pin can be inserted into the housing.

NOTE: Thread one of the retaining bolts into hole (A) to aid pin removal. Before using timing pin in timing procedure, remove the bolt from hole (A).

A. Threaded hole.

4. Insert the pin assembly in the timing hole. Move the governor control back and forth slowly between SHUT OFF and ZERO, to allow the pin to pass through the notch in the rack. The pin is in place when the head of the inverted bolt touches the fuel pump housing. With the rack in this position, the centerline of the second tooth on each fuel pump gear segment is aligned with the correct tooth on the rack.

5. Remove the standard spring and dust cover from the 9S215 Dial Indicator.


6. Install 5S8157 Extension to 9S239 Adapter. Slide 5S8088 Rod through the assembly (from the bottom) and install 5S8086 Point to rod at the top. Install the complete assembly into the hole for plug (3).

3. Plug.

NOTE: Install 3S3268 Contact Point on the 9S215 Dial Indicator.

7. With the rack held in the fuel-on direction, zero the 9S215 Dial Indicator. Do this by moving the indicator up or down, until the revolution counter lies between the red zero and black zero. Tighten the dial indicator retaining bolt. Now place the zero on the large dial under the indicator large hand by rotating the dial face.

8. Remove the rack centering pin and install it in its storage location.

9. Attach the end of the 8S4627 Circuit Tester to the brass screw terminal on the governor housing. Place the other end to a suitable ground.

10. Rotate the governor control lever in the fuel-on direction until the tester lights.

11. While holding the governor control lever in the fuel-on direction, slowly depress the dial indicator stem (slight pressure) until the test light just barely glows (a dim light); in this position, the rack stop collar is just touching the stop bar or torque spring. Rack setting dimension can now be read directly from the dial indicator. Refer to RACK SETTING INFORMATION to obtain the correct rack setting dimension.


12. If rack needs adjustment, loosen locknut (5) and turn adjusting screw (6) with wrench (4) until correct dimension is obtained.

13. After fuel rack has been adjusted, tighten locknut (5) to 11 ± 1 lb.ft. (1.5 ± 0.14 mkg).

4. 4B9820 Wrench. 5. Nut. 6. Adjusting screw.

Fuel Ratio Control Setting (Engines equipped with 3S8429 Fuel Ratio Control)

9S240 Rack Positioning Tool Group.

1. Check and/or adjust rack setting as indicated in the topic RACK ADJUSTMENT.

2. Leave the rack checking tools installed on the engine and install the fuel ratio control.

3. Move the override lever to RUN position and governor control to HIGH IDLE.

NOTE: Rack movement will be limited to less than HIGH IDLE by the fuel ratio control.

4. Hold the governor control in the HIGH IDLE position and observe the dimension on the dial indicator. The correct dimension is listed in the RACK SETTING INFORMATION.

5. If fuel ratio control adjustment is necessary, proceed as follows:

A. Remove cover (1).

B. Engage slot in cover (1) with cross-dowel in bolt (2) and turn adjusting bolt in as far as possible. This prevents the head of bolt (2) from limiting fuel rack travel.

1. Cover. 2. Adjusting bolt.

C. Move override lever to RUN position and governor control to HIGH IDLE. Hold governor control in HIGH IDLE position while making the adjustment.

D. Turn bolt (2) out with cover (1) until the correct dimension is obtained on the dial indicator.

E. After adjustment is made, turn cover (1) the amoung necessary to align the bolt holes and still obtain a dimension close to that specified in the RACK SETTING INFORMATION. Install the cover.

6. Remove the 9S239 Adapter Assembly (and related tools), 9S8519 Plug and 9S8521 Rod. Install the appropriate plug in place of 9S239 Adapter Assembly and 9S8519 Plug.

NOTE: Before starting the engine, make certain the governor control lever will move the governor to the SHUTOFF position and that all parts operate freely.

With the above initial adjustment made, a further adjustment can be made while the engine is running (if necessary) to improve engine performance. To reduce exhaust smoke during acceleration, turn cover (1) out (less fuel) 1/2 turn at a time until satisfactory. When exhaust smoke is acceptable but acceleration is sluggish, turn cover (1) in (more fuel) 1/2 turn at a time until satisfactory.

NOTE: Some exhaust smoke is likely to appear at maximum acceleration.

If acceleration is sluggish and full engine power seems to be lost, inspect the air line to the cover and the cover gasket for air leaks. If no air leaks are apparent, inspect the diaphragm. A damaged diaphragm will not allow the fuel rack to open completely, acceleration will be sluggish and full engine power cannot be obtained.

Fuel Ratio Control Setting (Engines equipped with 8S6419 Fuel Ratio Control)

OVERRIDE CONTROL LEVER: Bench setting adjustment is made in the following manner:

1. Control lever. 2. Adjusting screw. 3. Locknut.

1. Place lever (1) in start position.

2. Loosen locknut (3) and turn adjusting screw (2) counterclockwise as far as necessary to cause the lever to snap to run position when bolt (4) is pulled against the large spring pressure. Approximately 40 lb. (18.1 kg) pull is required to move the bolt.

3. Tighten the locknut.

4. Bolt in vise.

DIAPHRAGM: Bench test should be made with shop air pressure applied to the chamber above the diaphragm through port (5) in cover.

1. Application of 5 psi (0.35 kg/cm2) to chamber (6) should start movement of bolt (4).

4. Bolt. 5. Port. 6. Chamber. A. Start position. B. Run position.

2. Application of 16.5 to 20.5 psi (1.16 to 1.44 kg/cm2) pressure causes bolt (4) to be fully extended.
3. Pressure of 35 psi (2.46 kg/cm2) applied in the chamber (6) and turned off should drop no more than 2 psi (0.14 kg/cm2) in 10 seconds.

Hydraulic Air-Fuel Ratio Control Setting: On Engine

1. Check the fuel rack setting. Make reference to FUEL RACK SETTING. The fuel rack setting must be correct before the adjustment for the hydraulic air-fuel ratio control can be checked or changed.

2. Remove 9S8521 Rod and the 9S8519 Plug from the governor housing to let the speed limiter operate. Install the standard plug in the hole.

3. Remove the cover (1) from the hydraulic air-fuel ratio control.

4. Start the engine.

5. Push the end of valve (2) in and hold it in for two or three seconds. This action will manually move the valve into its operating position.

6. Move the governor control lever from the fuel off to the fuel on direction several times to remove the air from the control for a more accurate reading.

1. Cover. 2. Valve.

7. Rapidly move the governor control lever in the fuel on direction and read the measurement on the dial indicator. Read the indicator carefully because this reading will be a maximum for only a moment. Look in the RACK SETTING INFORMATION book to find the correct measurement.

8. To make an adjustment to the hydraulic air-fuel ratio control, turn valve (2) in a clockwise direction to make an increase in the limited rack position and in a counterclockwise direction to make a decrease in the limited rack position.

9. After each adjustment is made, the governor control lever must be moved from the fuel off to the fuel on direction before an accurate reading can be made.

10. After the correct adjustment has been made, put slot in cover (1) in alignment with pin in the valve and turn the cover to put it in alignment with the nearest bolt holes. Install the bolts.

11. Stop the engine.

12. After the oil pressure has gone out of the hydraulic air-fuel ratio control, full rack travel must be available. The speed limiter plunger will have to be pushed in to permit full rack travel.

13. Now install the wire and seal on the control.

Governor Linkage Adjustment

1P2385 Protractor Tool.

The linkage should be properly adjusted before any governor adjustments are made. Use of 1P2385 Protractor Tool is recommended.

With governor shaft and governor control linkage in shutoff position, adjust linkage as illustrated.

A. Linkage dimension 16 in. (406.4 mm). B. 30° ± 5 5°.

The 1P2385 Protractor Tool can be used to make the governor linkage adjustments. Illustrated here are three basic usages of the protractor tool.

First-Vertical housing face-to-lever angle.

Second-Horizontal or lever-to-lever angle.

Third-Lever-to-lever angle.

A. Indicator used for angle setting. B. Protractor plate edge in alignment with lever. C. Vertical housing face and extension arm are in alignment. D. Bubble in level. E. Indicator used for angle setting. F. Extension arm in alignment with lever. G. Extension arm in alignment with lever. H. Plate edge in alignment with second lever. I. Indicator used for angle setting. J. Angle between lever and vertical face of housing. K. Angle between level and lever. L. Angle between levers.

Air Induction And Exhaust System

Restrictions Of Air Inlet And Exhaust

Engine horsepower and efficiency will be reduced if either the air inlet system or exhaust becomes restricted.

The air cleaner should not restrict air flow to the point of 30 in. (762 mm) of water difference in pressure.

Exhaust back pressure (pressure difference measured between the turbocharger outlet elbow tap and the ambient air) should be no more than 20 in. (508 mm) of water, difference in pressure.

Measuring Inlet Manifold Pressure

By checking inlet manifold pressure, and comparing that pressure with the RACK SETTING INFORMATION, one can determine if an engine is operating efficiently. This test should be used if engine horsepower seems to be too low, yet no specific sympton of engine trouble is apparent.

Inlet manifold pressures in the RACK SETTING INFORMATION are recorded under specific operating conditions: 29.4 in. (746.76 mm) of mercury barometric pressure, 60°F (15.5°C) ambient temperature and 35 API rated fuel. Any deviation from these conditions can affect the inlet manifold pressure. Ambient air which is denser than that at 60°F/29.4 in. (15.5°C/746.76 mm) of mercury, can cause a slightly higher horsepower and inlet manifold pressure reading than listed in the RACK SETTING INFORMATION. If the ambient air is less dense, the horsepower and inlet manifold pressure rating can be slightly lower. Fuel density (API gravity rating) also affects the horsepower and inlet manifold pressure. If the fuel is rated above the standard 35 API gravity rating, the inlet manifold pressure can be slightly less than the value given in the RACK SETTING INFORMATION. If the fuel is rated below the standard rating, the inlet manifold pressure can be slightly more. BE SURE THE AIR INLET AND EXHAUST ARE NOT RESTRICTED WHEN CHECKING INLET MANIFOLD PRESSURE.

The components in a 4S6553 Instrument Group provide a means of reading engine rpm and inlet manifold pressure simultaneously. This group contains an instantaneous reading tachometer and a gauge for reading inlet manifold pressure. Instructions (FE036044) included with this group, explain the testing procedure.

1. Lid. 2. 4S6997 Manifold Pressure Gauge. 3. Pressure tap fitting. 4. 4S6992 Differential Pressure Gauges. 5. 4S6991 Tachometer. 6. Zero adjustment screws. 7. 8M2743 Gauge.

Exhaust temperature can be checked using the 1P3060 Pyrometer Group. Refer to the TOOL GUIDE. Special Instruction (GMG00697) explains the testing procedure.

Cylinder Condition

Engine cylinder condition can be analyzed with controlled pressure air through the engine cylinder precombustion chamber. Special Instruction (GMG00694) explains the procedure.

Air escaping from the exhaust opening indicates exhaust valve leakage. Air escaping from the air inlet indicates intake valve leakage. If air escapes from the crankcase breather during this test, it is an indication of piston, rings and/or liner faults.

Crankcase Pressure

Excessive crankcase pressure can be a result of combustion gas leaking past broken or damaged pistons and/or piston rings. This condition will usually be accompanied by irregular engine operation and excess fumes from crankcase breather opening. This pressure can cause the breather element to become restricted in an unusually short time. In addition, it can cause engine oil to leak past gaskets and seals that would function correctly under normal conditions.

Camshafts Timing

Whenever possible, always rotate the engine crankshaft to (TC) No. 1 compression position before removing a camshaft housing. It may be desirable to remove the injection nozzles to make crankshaft rotation easier.

The camshafts must be timed to the crankshaft with the crankshaft in No. 1 piston top center compression stroke position. Whenever a camshaft housing is removed, timing the camshaft to the crankshaft must be considered at time of camshaft housing installation.

On D349 Engines, if the crankshaft can be rotated to No. 1 top center compression position and remain there until all camshaft housings are installed, the driving camshaft housing (left front or right rear) can be removed and installed without removal of the driven camshaft housing (left rear or right front). However; the following instructions indicate the safest way, which is to remove the driven camshaft housing before installing the driving camshaft housing.

The D349 Engine has two camshaft housings coupled together on each bank of cylinders. Each housing contains an inlet and exhaust camshaft. The left front and right rear camshaft housings will be referred to as the driving camshaft housing (gear end) and the left rear and right front camshaft housings will be referred to as the driven camshaft housing (non-gear end). The camshafts, inlet and exhaust, of the driving and driven camshaft housings connect at the center of the cylinder block. One camshaft phasing gear in each driving housing is marked either "RIGHT BANK" or "LEFT BANK." All reference to camshafts being "RH" [right hand (right bank)] or "LH" [left hand (left bank)] are made when viewing forward from the flywheel end of the engine. No. 1 cylinder is at the right front of the cylinder block.

Installing Driving Camshaft Housing

1. With the driving camshaft housing removed from the engine, align camshaft phasing gear timing "V" marks (2). Install the timing pin in the appropriate timing hole in the inlet camshaft bearing journal.

NOTE: Timing pin (1) will drop into a timing hole in the inlet camshaft and timing "V" marks (2) will align when the gears are phased correctly.

1. Timing pin. 2. Timing "V" marks. 3. Inlet camshaft gear. 4. Dowel. 5. Exhaust camshaft gear.

2. Loosen valve lash adjusting screws in the camshaft housing being installed so fewer valve springs require compression.

3. If necessary, rotate the flywheel so No. 1 piston is at TC compression position.

NOTE: If the timing gears and opposite bank camshaft housings have not been removed, turn the crankshaft until the timing pin will drop into hole in inlet camshaft bearing journal of the undisturbed housing.

4. Install the driving camshaft housing on the cylinder head. One phasing gear in each housing is marked "RIGHT BANK" or "LEFT BANK" to identify its position.


Installing Driven Camshaft Housing

The driving camshaft housing should be installed and timed to the crankshaft before proceeding with driven camshaft housing installation.

The driven camshafts (inlet and exhaust) are marked in such a way that they can be used on either bank of cylinders for this engine. The markings on the inlet camshaft are "RH-IN" for use as right hand inlet and the same camshaft will have "LH-IN" for use as left hand inlet. The markings on the exhaust camshaft are "RH-EX" for use as right hand exhaust and "LH-EX" for use as a left hand exhaust. Each mark is directly in line with a timing pin hole. It is, therefore, of particular importance to be certain of the cylinder bank being worked on so the correct timing pin hole will be used. When the timing pin will go in a timing hole, the marking on the camshaft for that particular cylinder bank will be on top and clearly visible.


1. Install timing pins (6 and 7) in the inlet and exhaust camshafts for the driven camshaft housing.

2. Loosen the valve lash adjusting screws in camshaft housing being installed so fewer valve springs require compression.

6. Inlet camshaft timing pin. 7. Exhaust camshaft timing pin. 8. Collar assemblies (two; one each camshaft). 9. Camshaft drive collars (two; one for each camshaft).

3. Install camshaft drive collars (9) on the camshafts. Align the short spline tooth of the drive collars with the correspoinding area of the camshaft.

4. Install drive collar assemblies (8) into the camshaft housing.

5. Install driven camshaft housing to cylinder head.

6. Slide the drive collars into position so the driven camshafts are coupled with the driving camshafts. Install the drive collars retaining plate, lock and bolts.

7. Remove all timing pins and put them in their respective storage locations.

8. Install all components that were removed and then adjust the valves. See the topic, Valve Clearance Setting, also refer to Lubrication and Maintenance Procedures for valve adjusting procedure.

Valve Clearance Setting

Refer to the Lubrication and Maintenance Procedures for details of valve clearance adjustment.

Replacement Of Valve Guides

The intake and exhaust valves operate in replacement type valve guides. After the valves have been removed, clean the valve stems and valve guides.

Checking Valve Guide Bore

Use the 5P3536 Valve Guide Gauge Group to check the bore of the valve guides. Special Instructions GMG02562 gives complete and detailed instructions for use of the 5P3536 Dial Bore Gauge Group.


Valve Guides With Shoulders

Use the 7M3975 Driver to install the 2M6414, 9S9040, and 2N3293 Valve Guides. Put engine oil on the outside diameter of the valve guides before installing in the cylinder head.

The bore of the 2M6414 Valve Guides must be .3751 ± .0007 in. (9.528 ± 0.018 mm), the bore of the 9S9040 Valve Guides must be .3748 ± .0007 in. (9.520 ± 0.018 mm), and the bore of the 2N3293 Valve Guide must be .3727 ± .0005 in. (9.467 ± 0.013 mm) after they are installed in the cylinder head. If the bore in the valve guides is smaller than the dimensions given after they are installed in the cylinder head, they must be honed. Use the 1P7450 Valve Guide Honing Arrangement to hone the valve guides. Special Instruction GMG00966 gives complete and detailed instructions for the use of the 1P7450 Valve Guide Honing Arrangement.

Valve Guides That Do Not Have Shoulders

Use a 7M3975 Driver and a 5P1729 Bushing to install the 4N3666 Valve Guide. Put engine oil on the outside diameter of the valve guides before installing in the cylinder head.

The bore of the 4N3666 Valve Guide must be a minimum of .3725 in. (9.462 mm) after installation in the cylinder head. If the bore in the valve guide is smaller than .3725 in. (9.462 mm) after it is installed in the cylinder head, it must be honed to size. Use the 1P7450 Valve Guide Honing Arrangement to hone the valve guide. Special Instruction GMG00966 gives complete and detailed instructions for the use of the 1P7450 Valve Guide Honing Arrangement.

When honing a 4N3666 Valve Guide, hone to a size as close as possible to the minimum size of .3725 in. (9.462 mm) but do not hone to a size larger than .3736 in. (9.489 mm).

Lubrication System

Engine lubrication system problems are usually indicated by one of these symptoms:


Excessive Oil Consumption

External Leaks

Check crankshaft seals for leakage at both ends of the engine, look for leaks around the oil pan gasket and all lubrication system connections. Check to see if oil is being blown from the crankcase breather. This can be caused by combustion gases leaking past pistons. Clogged crankcase breathers will contribute to high crankcase pressure and result in gasket and seal leaks.

Leaking turbocharger shaft seals (turbine end) will cause loss of oil through the exhaust gases. This condition, "slobbering," is evidenced by oil at the exhaust outlet.

Internal Leakage Into Upper Cylinders

Upper cylinder oil leakage can be the cause of blue smoke. There are several possible routes for oil leakage into upper cylinders.

Oil can leak past the ring seals at the impeller end of the turbocharger shafts.

Leakage between worn guides and valves is also possible.

Worn or damaged piston rings or plugged oil return holes can cause oil to enter the upper cylinder. Incorrectly installed compression rings will cause oil to pump into the cylinders.

Excess oil usage can also be the result of oil viscosity being too low for prevailing conditions. Low oil viscosity can be caused by crankcase dilution, incorrect selection of oil weights, or engine overheating.

Oil can enter the inlet air manifold if the air fuel ratio control diaphragm is leaking and a vacuum condition exists in the inlet manifold. Restricted air cleaners can cause this vacuum condition.

Oil can also leak into the cooling system if oil cooler core or gaskets are leaking. Check the radiator or heat exchanger for signs of oil.

Low Oil Pressure

An oil pressure gauge that has a defect may give an indication of low oil pressure.


An 8M2744 Gauge which is part of 7S8875 Hydraulic Test Box can be used for checking pressure in the system.

Crankcase Lubricant Level

Oil level can be too low for oil pump suction bell pickup. Check oil level and add oil if necessary.

Pump Malfunctions

The oil pump inlet screen can be restricting the suction side of the pump which results in cavitation and loss of oil pressure. An air leak in the suction side of the pump will also cause cavitation and loss of pressure. An oil pump bypass valve that is stuck in the open (unseated) position will not allow system pressure to build to maximum pressures. The oil pump gears can be worn sufficiently to cause a reduction in pump output.

Oil Filter and Bypass Valve

If the oil filter is restricted and the filter bypass valve (end of filter housing) is stuck in the closed position, oil will relieve to the crankcase through the oil pump relief valve and pressure to the engine components will be inadequate. Install a new Caterpillar oil filter element, disassemble the bypass valve, clean the spring and plunger. Be sure the plunger moves freely before assembling.

Excessive Clearance in Engine Bearings or Open System

Worn components with extreme bearing clearances can cause engine oil pressure to be abnormally low. Any open, broken, or disconnected oil lines or passages will cause loss of oil pressure. Check gallery and crankshaft plugs to be sure they are in place.

Oil Cooler and Bypass Valve

Check the oil cooler oil passages for sludge. Clogged oil coolers and a stuck cooler bypass valve will be accompanied by high engine operating temperatures. Oil pressure will usually not lower due to sludge deposits alone. The cooler bypass valve must be stuck closed, or nearly so, to lower the oil pressure.

High Oil Pressure

This condition will occur when an oil pump bypass valve sticks in the closed position and the full pump volume is directed to the engine bearings.

Unusual Bearing Wear

Single components of the engine showing bearing wear at unusually frequent service intervals can be the result of clogged, restricted or broken oil passages. If the oil pressure gauge and operation of the speed limiter indicate main supply pressure is adequate yet a component shows bearing wear, check the branch supply line to that component.

Cooling System

The engine has a pressure type cooling system. A pressure type cooling system gives two advantages. The first advantage is that the cooling system can operate safely at a temperature that is higher than the normal point where water changes to steam. The second advantage is that this type system prevents cavitation (air in inlet of pump) in the water pump. With this type system it is more difficult for an air or steam pocket to form in the cooling system.

The cause for an engine getting too hot is generally because regular inspections of the cooling system were not done. Make a visual inspection of the cooling system before testing with testing equipment.

Visual Inspection Of The Cooling System

1. Check coolant level in the cooling system.

2. Look for leaks in the system.

3. Look for bent radiator fins. Be sure that air flow through the radiator does not have a restriction.

4. Check fan belts.

5. Check for damage to the fan blades.

6. Look for air or combustion gas in the cooling system.

7. Inspect the pressure cap and the sealing surface for the cap. The sealing surface must be clean.

8. Look for large amounts of dirt in the radiator core and on the engine.

Testing The Cooling System

Remember that temperature and pressure work together. When making a diagnosis of a cooling system problem, temperature and pressure must both be checked. Cooling system pressure will have an effect on cooling system temperatures. For an example, look at the chart to see the effect of pressure and the height above sea level on the boiling point (steam) of water.

Gauge for Water Temperature

9S9102 Thermistor Thermometer Group.2F7112 Thermometer.6B5072 Bushing.

If the engine gets too hot and a loss of coolant is a problem, a pressure loss in the cooling system could be the cause. If the gauge for water temperature shows that the engine is getting too hot, look for coolant leakage. If a place can not be found where there is coolant leakage, check the accuracy of the gauge for water temperature. Use the 9S9102 Thermistor Thermometer Group. This check can also be made by installing a 2F7112 Thermometer (using a 6B5072 Bushing) into the water manifold.


------ WARNING! ------

Be careful when working around an engine if it is running.


Start the engine. Put a cover over part of the radiator or cause a restriction of coolant flow. The reading on the gauge for water temperature should be the same as the reading on the thermistor thermometer.

Pressure Cap

One of the causes of cooling system pressure loss can be a faulty pressure cap seal. Inspect the pressure cap carefully for possible damage to the seal or sealing surfaces. The build-up of deposits on the cap, seal and filler neck should be removed.

Water Temperature Regulator

The regulator must be fully open at the following temperature:

6L5851 Regulator ... 197°F(92°C)

Test Procedure:

1. Heat water in a pan until the temperature of the water is correct for opening the regulator according to the chart.

2. Hang the regulator in the pan of water so it is completely under the water. The regulator must not be in contact with the sides or bottom of the pan during the test period.

3. During the test period, move (stir) the water around the inside of the pan to make all the water the same temperature.

4. After 10 minutes at the correct temperature, take the regulator out of the water.

5. Measure immediately the distance the regulator is open. The distance must be .375 in. (9.53 mm) or more.

6. Use a new regulator if the old regulator does not open correctly.

Basic Block

Cylinder Liners

1P2396 Adapter Plate.8B7548 Push Puller Crossbar and three 3H465 Plates.3/4"-10 NC Bolts, 3 in. (76.2 mm) long.3/4"-10 NC Bolts, 7 in. (177.8 mm) long.7M7875 Head Bolt Washers.8S3140 Cylinder Block Counterboring Tool Arrangement.1P5510 Liner Projection Tool Group.

Check liner projection above top plate as follows:

1. Make certain that top plate (4) and the cylinder liner flange are clean.

2. Use 3/4-10 NC bolts, 3 in. (76.2 mm) long, with two 7M7875 Washers (3) on each bolt to secure top plate (4) to the cylinder block. Place two bolts with washers on each side of the cylinder liner. Tighten the bolts evenly, in four steps; 10 lb.ft. (1.9 mkg), 25 lb.ft. (3.5 mkg), 50 lb.ft. (6.9 mkg) and finally to 70 lb.ft. (9.7 mkg).

1. 3H465 Plate. 2. 1P2396 Adapter plate. 3. Cylinder head bolt washers. 4. Top plate.

NOTE: To avoid moving bolts and washers as each liner is checked, install two bolts with washers on each side of each cylinder liner, along the entire length of the top plate.

3. Invert 3H465 Plate (1) from an 8B7548 Push Puller, in the center of adapter plate (2). Center crossbar (6) on the inverted 3H465 Plate. Using two 3/4"-10 NC bolts 7 in. (177.8 mm) long and two 3H465 Plates, secure the crossbar to the cylinder block as illustrated. Tighten the bolts evenly, in four steps; 5 lb.ft. (0.7 mkg), 15 lb.ft. (2.1 mkg), 25 lb.ft. (3.5 mkg) and finally to 50 lb.ft. (6.9 mkg). Distance from bottom edge of crossbar to top plate, must be the same on both sides of cylinder liner.

4. Zero the dial indicator using the back of 1P5507 Gauge with dial indicator (5) mounted in 1P2402 Block (7).

5. Measure liner projection as close as possible to the clamping area and at four locations around the liner. The liner projection must be within .002 to .0076 in. (0,05 to 0.19 mm) and the four measurements should not vary more than .001 in. (0.03 mm). The average projection between adjacent cylinders must not vary more than .001 in. (0.03 mm).

5. Dial indicator. 6. Crossbar. 7. 1P2402 Block.

NOTE: Measure and check the following dimensions when installing new parts. With all dimensions correct, proceed with the above listed Steps.

a. Top plate thickness .5142 ± .0010 in. (13.061 ± 0.025 mm).

b. Top plate gasket thickness, .008 ± .001 in. (0.20 ± 0.05 mm). (All surfaces must be clean and dry when installing gasket.)

c. Cylinder liner flange thickness, .5260 ± .0008 in. (13.360 ± 0.020 mm).

Liner projection can be adjusted by machining the contact face of the cylinder block with use of the 8S3140 Cylinder Block Counterboring Tool Arrangement. Form FM055228 is part of the cylinder block counterboring tool arrangement and gives tool usage information.

Shims of various thicknesses also are available to adjust liner projection.

Connecting Rods And Pistons

Use 7M3978 Piston Ring Expander to remove or install piston rings.

Use 7M3977 Piston Ring Compressor to install pistons into cylinder block.

Tighten connecting rod bolts in the following Step sequence.

Piston Ring Groove Gauge

A 5P3519 Piston Ring Groove Gauge is available for checking ring grooves with straight sides. For instructions on the use of the gauge, see the GUIDELINE FOR REUSABLE PARTS; PISTONS AND CYLINDER LINERS, Form No. REG01660.


Connecting Rod And Main Bearings

Bearings are available with a smaller inside diameter than the original size bearings. These bearings are for crankshafts that have been "ground" (made smaller than the original size). Main bearings are available with a larger outside diameter than the original size bearings. These bearings are for cylinder blocks that have had the bore for the main bearings "bored" (made larger than the original size).

Flywheel And Flywheel Housing

8S2328 Dial Indicator Group.

Heat the ring gear to install it. Do not heat to more than 600°F (315°C). Install the ring gear so the chamfer on the gear teeth is next to the starter pinion when the flywheel is installed.

Face Runout (axial eccentricity) of the Flywheel Housing

If any method other than given here is used, always remember bearing clearances must be removed to get correct measurements.

1. Fasten a dial indicator to the crankshaft flange so the anvil of the indicator will touch the face of the flywheel housing.

2. Force the crankshaft to the rear before reading the indication at each point.


3. With dial indicator set at .000 in. (0.0 mm) at location (A), turn the crankshaft and read the indicator at locations (B), (C) and (D).

4. The difference between lower and higher measurements taken at all four points must not be more than .012 in. (0.30 mm), which is the maximum permissible face runout (axial eccentricity) of the flywheel housing.

A. Bottom. B. Right side. C. Top. D. Left side.

Bore Runout (radial eccentricity) of the Flywheel Housing

1. With the dial indicator in position at (C), adjust the dial indicator to "0" (zero). Push the crankshaft up against the top bearing. Write the measurement for bearing clearance on line 1 in column (C).



2. Divide the measurement from Step 1 by 2. Write this number on line 1 in columns (B) & (D).

3. Turn the crankshaft to put the dial indicator at (A). Adjust the dial indicator to "0" (zero).

4. Turn the crankshaft counterclockwise to put the dial indicator at (B). Write the measurement in the chart.

5. Turn the crankshaft counterclockwise to put the dial indicator at (C). Write the measurement in the chart.

6. Turn the crankshaft counterclockwise to put the dial indicator at (D). Write the measurement in the chart.

7. Add lines I & II by columns.

8. Subtract the smaller number from the larger number in line III in columns (B) & (D). The result is the horizontal "eccentricity" (out of round). Line III, column (C) is the vertical eccentricity.

9. On the graph for total eccentricity find the point of intersection of the lines for vertical eccentricity and horizontal eccentricity.


10. If the point of intersection is in the range marked "Acceptable" the bore is in alignment. If the point of intersection is in the range marked "Not Acceptable" do Step 11.

11. Loosen the bolts holding the flywheel housing to the cylinder block. Hit the flywheel housing lightly with a hammer to put it in the correct position. Tighten the bolts holding the flywheel housing to the cylinder block and do Steps 1 through 10 again.

Face Runout (axial eccentricity) of the Flywheel

1. Install the dial indicator as shown. Put a force on the crankshaft the same way before the indicator is read to the crankshaft end clearance (movement) is always removed.


2. Set the dial indicator to read .000 in. (0.0 mm).

3. Turn the flywheel and read the indicator every 90°.

4. The difference between the lower and higher measurements taken at all four points must not be more than .006 in. (0.15 mm), which is the maximum permissible face runout (axial eccentricity) of the flywheel.

Bore Runout (radial eccentricity) of the Flywheel

1. Install the dial indicator (3) and make an adjustment of the universal attachment (4) so it makes contact as shown.

2. Set the dial indicator to read .000 in. (0.0 mm).

3. Turn the flywheel and read the indicator every 90°.

4. The difference between the lower and higher measurements taken at all four points must not be more than .006 in. (0.15 mm), which is the maximum permissible bore runout (radial eccentricity) of the flywheel.

1. 7H1945 Holding Rod. 2. 7H1645 Holding Rod. 3. 7H1942 Indicator. 4. 7H1940 Universal Attachment.

5. Runout (eccentricity) of the bore for the pilot bearing for the flywheel clutch, must not exceed .005 in. (0.13 mm).


Crankshaft Seals

Installation of the crankshaft front and rear seals, and the crankshaft rear wear sleeve requires the 9S8873 and 9S8881 Tool Groups. Specific installation instructions are in Special Instruction Form GMG00240, part of the tool groups.

Electrical System

Most of the tests of the electrical system can be done on the engine. The wiring insulation must be in good condition, the wire and cable connections must be clean and tight, and the battery must be fully charged. If the on the engine test shows a defect in a component, remove the component for more testing.


5P957 Coolant and Battery Tester5P300 Electrical Tester or9S1990 Battery Charger-Tester or1P7400 Battery Charger-Tester

The battery circuit is an electrical load on the charging unit. The load is variable because of the condition of the charge in the battery. Damage to the charging unit will result, if the connections, (either positive or negative) between the battery and charging unit are broken while the charging unit is charging. This is because the battery load is lost and there is an increase in charging voltage.

High voltage will damage, not only the charging unit but also the regulator and other electrical components.

------ WARNING! ------

Never disconnect any charging unit circuit or battery circuit cable from battery when the charging unit is charging.


Load test a battery that does not hold a charge when in use. To do this, put a resistance, across the main connections (terminals) of the battery. For a 6V battery, put a resistance of two times the ampere/hour rating. For a 12V battery, put a resistance of three times the ampere/hour rating. Let the resistance remove the charge (discharge) of the battery for 15 seconds and immediately test the battery voltage. A 6V battery in good condition will show 4.5V; a 12V battery in good condition will show 9V.

Complete operating instructions for the 5P300 Electrical Tester are inside the cover. When checking the battery with this tester, follow those instructions.

Make reference to Special Instruction GEG00058 when checking the battery with the 9S1990 or 1P7400 Battery Charger-Testers.


Charging System

The condition of charge in the battery at each regular inspection will show if the charging system is operating correctly. An adjustment is necessary when the battery is constantly in a low condition of charge or a large amount of water is needed (more than one ounce of water per cell per week or per every 50 service hours).

Make a test of the charging unit and voltage regulator on the engine, when possible, using wiring and components that are a permanent part of the system. Off the engine (bench) testing will give a test of the charging unit and voltage regulator operation. This testing will give an indication of needed repair. After repairs are made, again make a test to give proof that the units are repaired to their original operating condition.

Before starting the on engine testing, the charging system and battery must be checked as given in the Steps below.

1. Battery must be at least 75% (1.240 Sp. Gr.) full charged and held tightly in place. The battery holder must not put too much stress on the battery.

2. Cables between the battery, starter and engine ground must be the correct size. Wires and cables must be free of corrosion and have cable support clamps to prevent stress on battery connections (terminals).

3. Leads, junctions, switches and panel instruments that have direct relation to the charging circuit must give correct circuit control.

4. Inspect the drive components for the charging unit to be sure they are free of grease and oil and have the ability to operate the charging unit.

Alternator Regulator (Delco-Remy)

When an alternator is charging the battery too much or not enough, an adjustment can be made to the alternator regulator. Remove the plug from the cover of the alternator regulator and turn the inside adjustment with a screwdriver. Turn the adjustment one or two notches to change the alternator charging rate.

1. Hollow head screw, located on opposite side of alternator from output terminal.

The 1N9406 Alternator can be adjusted for either 30 or 32 volts. A replacement alternator shipped from the factory will be adjusted for 32 V systems. Where the alternator is to be used in a 30 V system, turn the adjustment screw two notches counterclockwise.

5S6698 and 5S9088 Alternator; Pulley Nut Tightening

Tighten nut holding the pulley to a torque of 75 ± 5 lb.ft. (10.4 ± 0.7 mkg) with the tools shown.

1. 8S1588 Adapter (1/2" female to 3/8" male). 2. 8S1590 Socket (5/16"-3/8" drive). 3. 1P2977 Tool Group. 8H8555 Socket (15/16"-1/2" drive) not shown.

Water Temperature Contactor Switch (5L6435)

Fabricated heat sink.2F112 Thermometer.3J5389 Plug.

1. Fabricate a heat sink as illustrated. Material can be brass, steel, or cast iron. Drill a 23/32in. hole through the heat sink and tap for 1/2 in. NPT.

2. Mark wiring connections to contactor terminals and disconnect wiring. "C" and "NO" terminals are normally used.

3. Remove the contactor and plug the opening with 3J5389 Plug. Install the contactor in the heat sink.

4. Reconnect the contactor to the wiring to check the entire system; contactor, wiring and shutoff solenoid.

HEAT SINK FOR TESTING [Dimensions in inches (mm)]

NOTE: if this cannot be done, use an ohmmeter or continuity tester across the contactor terminals to check the setting.

5. If the contactor is reconnected, start the engine and run it at low idle. The fuel pressure switch will complete the circuit to the shutoff solenoid.

6. Immerse heat sink and sensing element in water. Heat the water, and, by using an accurate thermometer, note the temperature at which engine shuts down (or continuity is indicated). [209° ± 1° F. (98° ± 1° C.)]. Allow water to cool. The contactor will reset automatically when the temperature lowers approximately 12° F. (8° C.) from the shutdown temperature.

1. 2F7112 Thermometer. 2. Fabricated heat sink.

7. Install new contactor if necessary.

NOTE: To test the system beyond the contactor, a jumper can be touched between the "C" and "NO" contactor terminals to simulate contactor operation.

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