Restriction Of Air Inlet And Exhaust
There will be a reduction in the performance of the engine if there is a restriction in the air inlet system or the exhaust system.
The air flow through a used air cleaner may have a restriction. The air flow through a plugged air cleaner will be restricted to some magnitude. In either case, the restriction must not be more than the following amount:
- 6.2 kPa (25 in H2O)
The air flow through a new air cleaner element must not have a restriction of more than the following amount:
- 3.7 kPa (15 in H2O)
Back pressure is the difference in the pressure between the exhaust at the outlet elbow and the atmospheric air. Back pressure from the exhaust must not be more than the following amount:
- 10.0 kPa (40 in H2O)
Measurement of Pressure In Inlet Manifold
| Tools Needed | ||
| Part Number | Part Name | Quantity |
| 1U-5470 | Engine Pressure Group | 1 |
The efficiency of an engine can be checked by making a comparison of the pressure in the inlet manifold with the information given in the TMI (Technical Marketing Information). The information is also listed on the Fuel Setting And Related Information Microfiche. This test is used when there is a decrease of horsepower from the engine, yet there is no real sign of a problem with the engine.
The correct pressure for the inlet manifold is listed in the TMI (Technical Marketing Information). The correct pressure is also on the Fuel Setting And Related Information Microfiche. Development of this information is performed under the following conditions:
- 99 kPa (29.7 in Hg) dry barometric pressure
- 29 °C (85 °F) outside air temperature
- 35 API rated fuel
On a turbocharged, aftercooled engine, a change in the fuel rating will change the horsepower. A change in the fuel rating will change the inlet manifold pressure. If the fuel is rated above 35 API, the inlet manifold pressure can be less than the pressure given in the TMI (Technical Marketing Information). The pressure will be less than the pressure listed on the Fuel Setting And Related Information Microfiche. If the fuel is rated below 35 API, the inlet manifold pressure can be more than the pressure listed in the TMI (Technical Marketing Information). The pressure can be more than the pressure that is listed on the Fuel Setting And Related Information Microfiche.
Note: Ensure that the air inlet and the exhaust are not restricted when you are checking the inlet manifold pressure.
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| Illustration 1 | g00434159 |
Pressure test location on inlet manifold (1) Plug | |
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| Illustration 2 | g00293196 |
1U-5470 Engine Pressure Group | |
To measure the inlet manifold pressure, remove plug (1) from the inlet manifold. Use the 1U-5470 Engine Pressure Group in order to check the inlet manifold pressure. The Special Instruction, SEHS8907 contains instructions for the tool.
Exhaust Temperature
| Tools Needed | ||
| Part Number | Part Name | Quantity |
| 123-6700 | Laser Infrared Thermometer | 1 |
Use the 123-6700 Laser Infrared Thermometer to check exhaust temperature. The Operator's Manual, NEHS0630 contains the complete operating and maintenance instructions for the 123-6700 Laser Infrared Thermometer .
Air-To-Air Aftercooled Systems
| Tools Needed | ||
| Part Number | Part Name | Quantity |
| FT-1984 | Aftercooler Testing Group | 1 |
| FT-1438 | Aftercooler (Dynamometer Test) | 1 |
Visual Inspection
Inspect the following parts at each oil change:
- Air lines
- Hoses
- Gasket joints
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Pressurized air can cause personal injury. When pressurized air is used for cleaning, wear a protective face shield, protective clothing, and protective shoes. |
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Ensure that the constant torque hose clamps are tightened to the correct torque. Check the truck manufacturer's specifications for the correct torque. Check the welded joints for cracks. Ensure that the brackets are tightened in the correct positions. Ensure that the brackets are in good condition. Use compressed air to clean any debris or any dust from the aftercooler core assembly. Inspect the cooler core fins for the following conditions:
- Damage
- Debris
- Corrosion
Use a stainless steel brush to remove any corrosion. Ensure that you use soap and water.
Note: When parts of the air-to-air aftercooler system are repaired, a leak test is recommended. When parts of the air-to-air aftercooler system are replaced, a leak test is recommended.
The use of winter fronts or shutters is discouraged with air-to-air aftercooled systems. Winter fronts can only be used on certain truck models. On these trucks, tests have shown that the engine jacket water will overheat before the inlet manifold air temperature is excessive. These trucks use sensors and indicators that are installed in order to indicate engine operating conditions before excessive inlet manifold air temperatures are reached. Check with the truck manufacturer about the use of both winter fronts and shutters.
Air System Restriction
Pressure measurements should be taken at the turbocharger outlet and at the inlet manifold. The air lines and the cooler core must be inspected for internal restriction when both of the following conditions are met:
- Air flow is at a maximum level.
- Total air pressure drop of the charged system exceeds 13.5 kPa (4 in Hg).
If a restriction is discovered, proceed with the following tasks, as required:
- Clean
- Repair
- Replacement
Turbocharger Failure
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Personal injury can result from air pressure. Personal injury can result without following proper procedure. When using pressure air, wear a protective face shield and protective clothing. Maximum air pressure at the nozzle must be less than 205 kPa (30 psi) for cleaning purposes. |
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If a turbocharger failure occurs, remove the air-to-air aftercooler core. Internally flush the air-to-air aftercooler core with a solvent that removes oil and other foreign substances. Shake the air-to-air aftercooler core in order to eliminate any trapped debris. Wash the aftercooler with hot, soapy water. Thoroughly rinse the aftercooler with clean water and blow dry the aftercooler with compressed air. Blow dry the assembly in the reverse direction of normal air flow. To make sure that the whole system is clean, carefully inspect the system.
| NOTICE |
|---|
Do not use caustic cleaners to clean the air-to-air aftercooler core. Caustic cleaners will attack the internal metals of the core and cause leakage. |
Inlet Manifold Pressure
Normal inlet manifold pressure with high exhaust temperature can be caused by blockage of the aftercooler core fins. Clean the fins of the aftercooler core. Refer to "Visual Inspection" for the cleaning procedure.
Low inlet manifold pressure and high exhaust manifold temperature can be caused by any of the following conditions:
Plugged air cleaner - Clean the air cleaner or replace the air cleaner, as required. Refer to the Operation and Maintenance Manual.
Blockage in the air lines - Blockage in the air lines between the air cleaner and the turbocharger must be removed.
Aftercooler core leakage - Aftercooler core leakage should be pressure tested. Refer to the "Aftercooler Core Leakage" topic for the correct testing procedure.
Leakage of the induction system - Any leakage from the pressure side of the induction system should be repaired.
Inlet manifold leak - An inlet manifold leak can be caused by the following conditions: loose fittings and plugs, missing fittings and plugs, damaged fittings and plugs and leaking inlet manifold gasket.
Aftercooler Core Leakage
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| Illustration 3 | g00295702 |
FT-1984 Aftercooler Testing Group (1) Regulator and valve assembly (2) Nipple (3) Relief valve (4) Tee (5) Coupler (6) Aftercooler (7) Dust plug (8) Dust plug (9) Chain | |
A low power problem in the engine can be the result of aftercooler leakage. Aftercooler system leakage can result in the following problems:
- Low power
- Low boost pressure
- Black smoke
- High exhaust temperature
| NOTICE |
|---|
Remove all air leaks from the system to prevent engine damage. In some operating conditions, the engine can pull a manifold vacuum for short periods of time. A leak in the aftercooler or air lines can let dirt and other foreign material into the engine and cause rapid wear and/or damage to engine parts. |
A large leak of the aftercooler core can often be found by making a visual inspection. To check for smaller leaks, use the following procedure:
- Disconnect the air pipes from the inlet and outlet side of the aftercooler core.
- Install couplers (5) on each side of the aftercooler core. Also, install dust plugs (7) and (8). These items are included with the FT-1984 Aftercooler Testing Group.
Note: Installation of additional hose clamps on the hump hoses is recommended in order to prevent the hoses from bulging while the aftercooler core is being pressurized.
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Dust plug chains must be installed to the aftercooler core or to the radiator brackets to prevent possible injury while you are testing. Do not stand in front of the dust plugs while you are testing. |
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- Install the regulator and valve assembly (1) on the outlet side of the aftercooler core assembly. Also, attach the air supply.
| NOTICE |
|---|
Do not use more than 240 kPa (35 psi) of air pressure or damage to the aftercooler core can be the result. |
- Open the air valve and pressurize the aftercooler to 205 kPa (30 psi). Shut off the air supply.
- Inspect all connection points for air leakage.
- The aftercooler system's pressure should not drop more than 35 kPa (5 psi) in 15 seconds.
- If the pressure drop is more than the specified amount, use a solution of soap and water to check all areas for leakage. Look for air bubbles that will identify possible leaks. Replace the aftercooler core, or repair the aftercooler core, as needed.
- After the testing, remove the FT-1984 Aftercooler Testing Group. Reconnect the air pipes on both sides of the aftercooler core assembly.
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To help prevent personal injury when the tooling is removed, relieve all pressure in the system slowly by using an air regulator and a valve assembly. |
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Dynamometer Test
In hot ambient temperatures, chassis dynamometer tests for models with an air-to-air aftercooler can add a greater heat load to the jacket water cooling system. Therefore, the jacket water cooling system's temperature must be monitored. The following measurements may also need a power correction factor:
- Inlet air temperature
- Fuel API rating
- Fuel temperature
- Barometric pressure
With dynamometer tests for engines, use the FT-1438 Aftercooler (Dynamometer Test). This tool provides a water cooled aftercooler in order to control the inlet air temperature to 43 °C (110 °F).
Crankcase Pressure (Crankshaft Compartment)
| Tools Needed | ||
| Part Number | Part Name | Quantity |
| 8T-2700 | Blowby/Air Flow Indicator | 1 |
Damaged pistons or rings can cause too much pressure in the crankcase. This condition will cause the engine to run rough. There will be more than the normal amount of fumes (blowby) rising from the crankcase breather. The breather can then become restricted in a very short time, causing oil leakage at gaskets and seals that would not normally have leakage. Blowby can also be caused by worn valve guides or by a failed turbocharger seal.
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| Illustration 4 | g00286269 |
8T-2700 Blowby/Air Flow Indicator | |
The 8T-2700 Blowby/Air Flow Indicator is used to check the amount of blowby. The Special Instruction, SEHS8712 contains the test procedure for checking the blowby.
Compression
An engine that runs roughly can have a leak at the valves. An engine that runs roughly can also have valves that need an adjustment. Remove the head and inspect the valves and valve seats. This is necessary to find those small defects that would not normally cause problems. Repairs of these problems are normally performed when you are reconditioning the engine.
Valve Lash
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To prevent possible injury, do not use the starter to turn the flywheel. Hot engine components can cause burns. Allow additional time for the engine to cool before measuring valve clearance. |
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This engine uses high voltage to control the fuel injectors. Disconnect electronic fuel injector enable circuit connector to prevent personal injury. Do not come in contact with the fuel injector terminals while the engine is running. |
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Note: Valve lash is measured between the rocker arm and the valve bridge. All measurements and adjustments must be made with the engine stopped and the valves fully closed.
Valve Lash Check
An adjustment is not necessary if the measurement of the valve lash is in the acceptable range. Check the valve lash while the engine is stopped. The valve lash setting is specified in Table 5.
| Quick Reference for Engine Valve Lash Setting C-10 and C-12 Engines |
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|---|---|---|
| Inlet Valves | Exhaust Valves | |
| Valve Lash Setting | 0.38 ± 0.08 mm (0.015 ± 0.003 inch) |
0.64 ± 0.08 mm (0.025 ± 0.003 inch) |
| TC Compression Stroke | 1-2-4 | 1-3-5 |
| TC Exhaust Stroke (1) | 3-5-6 | 2-4-6 |
| Firing Order | 1-5-3-6-2-4 (2) | |
| ( 1 ) | 360° from TC compression stroke |
| ( 2 ) | The No. 1 cylinder is at the front of the engine. |
If the measurement is not within this range, an adjustment is necessary. Refer to "Valve Lash Adjustment" for the proper procedure.
Valve Lash Adjustment
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| Illustration 5 | g00386924 |
Cylinder and valve location (A) Exhaust valves (B) Inlet valves | |
| Engine Valve Lash Setting | |
|---|---|
| Valves | Valve Lash Setting |
| Inlet | 0.38 ± 0.08 mm (0.015 ± 0.003 inch) |
| Exhaust | 0.64 ± 0.08 mm (0.025 ± 0.003 inch) |
Adjust the valve lash while the engine is stopped. Use the following procedure to adjust the valve lash:
- Put the No. 1 piston at the top center position. Refer to Testing and Adjusting, "Fuel System".
Note: If the engine is equipped with an engine compression brake, loosen the adjusting screw for the lash on the slave piston for the compression brake prior to adjusting the engine valve lash. Refer to the Testing and Adjusting, "Compression Brake" for information that relates to the adjustment of the slave piston lash for the engine compression brake.
- Before any adjustments are made, lightly tap the rocker arm at the top of the adjustment screw with a soft mallet. This will ensure that the lifter roller seats against the camshaft's base circle.
Note: Refer to Table 6 for the appropriate engine valve lash setting.
- Make an adjustment to the valve lash on the inlet valves for cylinders 1, 2, and 4.
- Loosen adjustment locknut (2) .
Show/hide table
Illustration 6 g00481639
Engine valve lash adjustment
Typical example
(1) Rocker arm
(2) Adjustment locknut
- Place the appropriate feeler gauge between rocker arm and the valve bridge. Then, turn the adjustment screw in a clockwise direction. Slide the feeler gauge between the rocker arm and the valve bridge. Continue turning the adjustment screw until a slight drag is felt on the feeler gauge. Remove the feeler gauge.
- Tighten the adjustment locknut to a torque of 30 ± 7 N·m (22 ± 5 lb ft). Do not allow the adjustment screw to turn while you are tightening the adjustment locknut. Recheck the valve lash after tightening the adjustment locknut.
- Make an adjustment to the valve lash on the exhaust valves for cylinders 1, 3, and 5.
- Loosen adjustment locknut (2) .
- Place the appropriate feeler gauge between rocker arm and the valve bridge. Then, turn the adjustment screw in a clockwise direction. Slide the feeler gauge between the rocker arm and the valve bridge. Continue turning the adjustment screw until a slight drag is felt on the feeler gauge. Remove the feeler gauge.
- Tighten the adjustment locknut to a torque of 30 ± 7 N·m (22 ± 5 lb ft). Do not allow the adjustment screw to turn while you are tightening the adjustment locknut. Recheck the valve lash after tightening the adjustment locknut.
- Remove the timing bolt and turn the flywheel by 360 degrees in the direction of engine rotation. This will put the No. 6 piston at the top center position on the compression stroke. Install the timing bolt in the flywheel.
- Before any adjustments are made, lightly tap the rocker arm at the top of the adjustment screw with a soft mallet. This will ensure that the lifter roller seats against the camshaft's base circle.
- Make an adjustment to the valve lash on the inlet valves 3, 5, and 6.
- Lightly tap the rocker arm at the top of the adjustment screw with a soft mallet. This will ensure that the lifter roller seats against the camshaft's base circle.
- Loosen the adjustment locknut.
- Place the appropriate feeler gauge between rocker arm and the valve bridge. Then, turn the adjustment screw in a clockwise direction. Slide the feeler gauge between the rocker arm and the valve bridge. Continue turning the adjustment screw until a slight drag is felt on the feeler gauge. Remove the feeler gauge.
- Tighten the adjustment locknut to a torque of 30 ± 7 N·m (22 ± 5 lb ft). Do not allow the adjustment screw to turn while you are tightening the adjustment locknut. Recheck the valve lash after tightening the adjustment locknut.
- Make an adjustment to the valve lash on the exhaust valves for cylinders 2, 4, and 6.
- Loosen adjustment locknut (2) .
- Place the appropriate feeler gauge between rocker arm and the valve bridge. Then, turn the adjustment screw in a clockwise direction. Slide the feeler gauge between the rocker arm and the valve bridge. Continue turning the adjustment screw until a slight drag is felt on the feeler gauge. Remove the feeler gauge.
- Tighten the adjustment locknut to a torque of 30 ± 7 N·m (22 ± 5 lb ft). Do not allow the adjustment screw to turn while you are tightening the adjustment locknut. Recheck the valve lash after tightening the adjustment locknut.
- Remove the timing bolt from the flywheel after all adjustments to the valve lash have been made. Reinstall the timing cover on the flywheel housing.
For information that relates to the adjustment of the electronic unit injector, refer to Testing and Adjusting, "Fuel System".