G3612 and G3616 Engines Caterpillar

Engine Timing Procedures

Usage:

Many procedures (disassembly and assembly, testing and adjusting, etc.) require the timing of the engine or the engine components. The engines are considered in time when the following conditions are met:

The No. 1 cylinder is at the top center (TC) position on the compression stroke.
The crankshaft timing pin is engaged in the bracket which is attached to the crankshaft.
Both camshaft timing pins are engaged in the holes in the camshaft assemblies.

Engine Rotation

When you view the engine from the flywheel end, the SAE standard engine crankshaft rotation is counterclockwise.

Note: The front end of the engine is opposite the flywheel end of the engine.

The left side and the right side are viewed from the flywheel end of the engine.

Engine Prelubrication

Many service and inspection procedures require rotation of the engine crankshaft. The prelubrication of the engine is required when the crankshaft is rotated during normal maintenance operations. This includes adjusting the valves and starting the engine.

The push button for the engine prelube is located on the panel for the Engine Supervisory System. The push button provides a manual method in order to prelube the engine.

Do not use the air or electric starting motors to rotate the crankshaft. If the crankshaft is rotated too fast, oil from the prelube pump will not be enough to protect the engine.

Use the manual barring group to rotate the engine for service work. Leave the prelube pump on during crankshaft rotation. Damage can result if the crankshaft is rotated on dry bearing surfaces.

Show/hide table

NOTICE

In order to avoid possible damage to the engine, the prelube pump should not be operated continuously for extended periods of time. During repairs, if the prelube pump has run for more than three hours continuously, any oil that may have collected in the cylinders and/or above the valves should be removed before attempting to start the engine.

Finding the Top Center Compression Position for No. 1 Cylinder

Show/hide table




Illustration 1	g00311103
Location of the timing pin (1) Manual barring group (2) Storage position of the timing pin

Remove the crankshaft timing pin from the storage position (2). The storage position of the timing pin is located below manual barring group (1) .

Show/hide table




Illustration 2	g00311105
Installation of the crankshaft timing pin (3) Flywheel timing bracket (4) Mounting bracket for the timing pin (5) Timing pin

Prelube the engine. Use the manual barring group to turn the engine flywheel in the direction of normal engine rotation. Turn the engine until crankshaft timing pin (5) can be installed through the mounting bracket for the timing pin (4). Ensure that the crankshaft timing pin is engaged in flywheel timing bracket (3) .
Note: If the flywheel is turned beyond the point of installation in the flywheel timing bracket, the backlash must be removed from the timing gears. Turn the flywheel in the opposite direction of normal rotation for approximately 20 degrees. Then turn the flywheel in the direction of normal engine rotation until the timing pin can be installed in the bracket assembly. This procedure ensures that the backlash is removed from the timing gears.
Note: There is an alternate method that can be used to determine that the No. 1 cylinder is at TC. Visually check the location of the hole in the flywheel. If the No. 1 cylinder is at TC, the hole in the flywheel for the crank angle sensor (CAS) will be positioned directly opposite the CAS.

Remove the valve cover from the No. 1 cylinder head.

The inlet and exhaust valves for the No. 1 cylinder are fully closed if No. 1 piston is on the compression stroke and the rocker arms can be moved by hand. If the rocker arms cannot be moved and the valves are slightly open, the No. 1 piston is on the exhaust stroke. Refer to Table "Crankshaft Positions for Valve Lash Setting" in order to determine the correct cylinders that need to be checked and/or adjusted for the stroke position of the crankshaft when the timing pin has been installed in the crankshaft.
Note: When the actual stroke position is identified and the other stroke position is needed, remove all timing pins from the engine. Turn the flywheel for 360 degrees in the direction of the normal rotation.

Show/hide table




Illustration 3	g00471973
G3612 Engine cylinder and valve location (A) Inlet valve (B) Gas admission valve (C) Exhaust valve

Show/hide table




Illustration 4	g00472128
G3616 Engine cylinder and valve location (A) Inlet valve (B) Gas admission valve (C) Exhaust valve

Camshaft Timing Check

Remove rear camshaft inspection covers from both sides of the engine.

Put the No. 1 piston at the Top Center Position on the compression stroke. Refer to "Finding the Top Center Compression Position for No. 1 Cylinder".

When the crankshaft timing pin is installed and the No. 1 piston is on the compression stroke, remove the camshaft timing pin from the storage position.

Show/hide table




Illustration 5	g00311143
Installation of camshaft timing pin (1) Timing pin (2) Camshaft

Install timing pin (1) through the timing pin hole and into the hole in camshaft (2) .

If the timing pin does not go into the hole in the camshaft, the engine is not timed correctly and the camshaft position must be adjusted. Refer to "Camshaft Timing Adjustment".

Camshaft Timing Adjustment

Note: Before you perform any timing adjustments, check the timing in order to ensure that an adjustment is necessary. Refer to "Camshaft Timing Check " for this procedure.

If the camshaft is timed with the crankshaft, the camshaft drive gear must be removed and the camshaft must be rotated. Follow steps 1 through 7 if adjustment of the camshaft is necessary.

Put the No. 1 cylinder in the TC position of the compression stroke and install the crankshaft timing pin. Remove all of the valve covers from the side of the engine that requires adjustment.

Show/hide table




Illustration 6	g00311255
(1) Bolts (2) Rocker arm shaft

Loosen bolts (1) that hold rocker arm shafts (2) until all of the rocker arms are free from the valve bridges.

Show/hide table




Illustration 7	g00488801
Rear view of the engine (3) Camshaft drive gear covers

Remove the crankshaft timing pin and camshaft drive gear covers (3) from the rear housing.

Show/hide table




Illustration 8	g00311258
(4) Camshaft drive gear (5) Bolts (6) Bolt (7) Washer (8) Plate

Loosen the camshaft drive gears (4) by using the following procedure:

Use a 6V-6080 Torque Multiplier Gp and a 5P-1748 Socket to loosen bolt (6) .

Remove bolt (6) and washer (7). Remove bolts (5) and plate (8) .

Put washer (7) between the camshaft and plate (8) as shown Illustration 8. Install bolt (6) finger tight.

Install bolts (5) finger tight.

Show/hide table

Sudden movement of camshaft drive gear can occur when the camshaft drive gear is pulled off the taper of the camshaft. To prevent possibly personal injury, be sure that the bolt is installed (finger tight) to restrict the movement of the camshaft drive gear when the camshaft drive gear is pulled off of the taper of the camshaft.

Tighten bolts (5) evenly in order to pull camshaft drive gear (4) off the taper of the camshaft.

Show/hide table




Illustration 9	g00311259
(9) Camshaft timing pin

Install the crankshaft timing pin. Remove the camshaft timing pin (9) from the storage location.

Put camshaft timing pin in the timing pin hole. Rotate the camshaft until the timing pin goes into the hole in the camshaft.

After the camshaft is timed with the crankshaft, tighten camshaft drive gear (4) by using the following procedure:
1. Remove bolts (5) and (6), plate (8) and washer (7) .
1. Install washer (7) and bolt (6). Tighten bolt (6) by hand.
1. Remove the crankshaft timing pin and the camshaft timing pin.
1. Rotate the flywheel in the opposite direction of normal rotation for a minimum of 20 degrees.
1. Turn the flywheel in the direction of normal engine rotation until the crankshaft timing pin can be reinstalled in the crankshaft. This procedure holds the backlash in the timing gears in the direction of normal engine rotation.
1. Reinstall the camshaft timing pin in order to verify the camshaft position. To prevent damage to the timing pins, remove the crankshaft timing pin and the camshaft timing pin before tightening bolt (6) .
1. Use a 6V-6080 Torque Multiplier Gp and a 5P-1748 Socket to tighten bolt (6) to a torque of 2000 ± 275 N·m (1480 ± 200 lb ft).
1. Use a hammer to strike the plate (8). Repeat Step 7.g.
1. Repeat Step 7.h until there is no movement of the gear on the shaft at full torque.

Repeat the "Camshaft Timing Check" procedure to verify the correct crankshaft to camshaft timing. If the camshaft timing is not correct, repeat the "Camshaft Timing Adjustment" procedure.

Remove the crankshaft timing pin and camshaft timing pin. Return the pins to the storage locations. Install the camshaft inspection covers on the side of the cylinder block.

Install camshaft drive gear covers (3) on the rear housing.

Tighten the bolts that hold the rocker arm shafts in position, and adjust the valve lash.

Install the valve covers.

Bridge Adjustment

If the cylinder head is disassembled, keep the bridges with the respective valves. To adjust the bridges, use the procedure that follows:

Note: The bridges can be adjusted without removal of the rocker arms and shafts. Valves must be fully closed when adjustment is made. Refer to "Finding the Top Center Compression Position for No. 1 Cylinder" and "Crankshaft Positions for Valve Lash Setting" in order to determine when the valves are fully closed.

Show/hide table




Illustration 10	g00311260
(1) Rocker arm (2) Valve cover (3) Valve bridge (4) Adjusting screw and locknut for the valve bridge (5) Bridge dowel

Note: If the cylinder head is not disassembled, omit Steps 1 and 2.

If the cylinder head has been disassembled, check that the bridge dowels are installed to the correct height. Lubricate the bridge dowel, the bridge dowel bore and the top contact surface of the bridge.

Install the bridge on the dowel.

Remove valve cover (2) and loosen the locknut on adjusting screw (4). Loosen the adjusting screw by several turns.

Firmly press on rocker arm (1) at the area of contact with bridge (3). Turn the adjusting screw in the clockwise direction until the screw just contacts the valve stem.

Turn the adjusting screw by an additional 45 ± 5 degrees. This will equalize clearance between the bridge and the bridge dowel (5) .

Hold the adjusting screw in order to maintain 45 ± 5 degrees. Tighten the locknut to a torque of 100 ± 15 N·m (75 ± 11 lb ft).

Ensure that the valve lash is correct. Refer to "Valve Lash" for the procedures to use.

Crankshaft Positions for Valve Lash Setting

Show/hide table




Illustration 11	g00471973
G3612 Engine cylinder and valve location (A) Inlet valve (B) Gas admission valve (C) Exhaust valve

Show/hide table

Table 1
Crankshaft Positions For Valve Lash Setting
G3612 Engine	TC Compression Stroke	TC Exhaust Stroke
Standard Counterclockwise Rotation ⁽¹⁾
Inlet Valves	1-3-6-7-10-12	2-4-5-8-9-11
Exhaust Valves	1-4-5-6-9-12	2-3-7-8-10-11
Gas Admission Valves	1-6-7-9-10-12	2-3-4-5-8-11
Firing Order	1-12-9-4-5-8-11-2-3-10-7-6

Show/hide table

^( 1 )

Put the No. 1 piston at the top center (TC) position. Ensure the identification for the correct stroke. Refer to "Finding the Top Center Position for No. 1 Piston". After the adjustments are made for the correct cylinders, remove the timing pin. Turn the flywheel for 360 degrees in the direction of normal engine rotation. This will put No. 1 piston at the TC position on the opposite stroke. Install the timing pin in the crankshaft and complete the adjustments for the cylinders that remain.

Show/hide table




Illustration 12	g00472128
G3616 Engine cylinder and valve location (A) Inlet valve (B) Gas admission valve (C) Exhaust valve

Show/hide table

Table 2
Crankshaft Positions For Valve Lash Setting
G3616 Engine	TC Compression Stroke	TC Exhaust Stroke
Standard Counterclockwise Rotation ⁽¹⁾
Inlet Valves	1-2-5-7- 8-12-13-14	3-4-6-9- 10-11-15-16
Exhaust Valves	1-2-3-4- 5-6-7-8	9-10-11-12- 13-14-15-16
Gas Admission Valves	1-2-5-6- 7-8-13-14	3-4-9-10- 11-12-15-16
Firing Order	1-2-5-6-3-4-9-10- 15-16-11-12-13-14-7-8

Show/hide table

^( 1 )

Put the No. 1 piston at the TC position. Ensure the identification for the correct stroke. Refer to "Finding the Top Center Position for No. 1 Piston". After the adjustments are made for the correct cylinders remove the timing pin. Turn the flywheel for 360 degrees in the direction of normal engine rotation. This will put No. 1 piston at the TC position on the opposite stroke. Install the timing pin in the crankshaft and complete the adjustments for the cylinders that remain.

Valve Lash

Show/hide table

Table 3
Tools Needed		Quantity
4C-6593	Adjustment Tool	1
6V-3075	Dial Indicator	1
8S-3675	Indicator Contact Point	1

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

Measure the inlet valve lash and the exhaust valve lash. Perform checks and adjustments with the engine stopped. The valve must be fully closed. An adjustment is not necessary if the measurements are within the tolerances that are given in Table 4. There is no range for the gas admission valve.

Show/hide table

Table 4
Valve Lash Check with Engine Stopped
Valves	Acceptable Range for Lash
Inlet	0.42 to 0.58 mm (0.017 to 0.023 inch)
Exhaust	1.19 to 1.35 mm (0.047 to 0.053 inch)

If the measurements are not within tolerance, adjustment is necessary. Refer to "Valve Lash Adjustment".

Valve Lash Adjustment

Show/hide table

Table 5
Tools Needed		Qty
4C-6593 Adjustment Tool ⁽¹⁾		1
6V-3075 Dial Indicator ⁽¹⁾		1
8S-3675 Indicator Contact Point ⁽¹⁾		1
214-1168 Socket ⁽²⁾		1
5P-0333 Wrench ⁽²⁾		1

Show/hide table

^( 1 )	Insert the contact point into the dial indicator. Insert the dial indicator into the adjustment tool. Tighten the retaining screw finger tight.
^( 2 )	To facilitate the use of a torque wrench, weld the jaw of the 5P-0333 Wrench around the top end of the 1U-7133 Socket .

Valve lash dimensions are made to specific values. No tolerance is provided.

Use the procedure that follows for adjustment of the valves:

Put the No. 1 piston at the TC position. Refer to "Finding the Top Center Compression Position for No. 1 Cylinder".

Note: Before any actual adjustments are made, lightly tap each rocker arm at top of adjustment screw with a soft hammer in order to ensure that the lifter roller is seated against the base circle of the camshaft lobe.

Insert the 8S-3675 Indicator Contact Point into the 6V-3075 Dial Indicator. Insert the 6V-3075 Dial Indicator into the 4C-6593 Adjustment Tool. Tighten the retaining screw finger tight.

Install the adjustment tool on the rocker base. Thread the adjustment tool into the hole that is nearest to the end of the rocker arm. Position the contact point of the dial indicator over the flat area on the end of the rocker arm. Tighten the knob. Rotate the dial indicator so the dial indicator can be easily read. Check that the tool is rigid. Check that the tip of the dial indicator moves freely.

Show/hide table




Illustration 13	g00311261
An installed 4C-6593 Adjustment Tool

Loosen the adjustment screw locknut for the rocker arm. Turn the rocker arm adjustment screw clockwise until there is no valve lash. Turn the valve adjusting screw counterclockwise. The valve lash should be zero. At this point, the valves should be fully closed.

Zero the dial indicator.

Lift up firmly on the valve end of the rocker arm. Turn the valve adjusting screw until you achieve the setting that is specified in Table 6.
Show/hide table
Table 6
Valve Lash Setting with Engine Stopped

Inlet
0.50 mm (0.020 inch)

Exhaust
1.27 mm (0.050 inch)

Table 6
Valve Lash Setting with Engine Stopped
Inlet	0.50 mm (0.020 inch)
Exhaust	1.27 mm (0.050 inch)

Try to move the rocker arm by a small amount while you are lifting the rocker arm. The dial indicator reading will vary. Read the dial indicator when the rocker arm fits in the groove for the rocker arm.

Show/hide table




Illustration 14	g00311262

After each adjustment, tighten the locknut for the adjustment screw to a torque of 200 ± 25 N·m (150 ± 18 lb ft). Check the valve lash again. Repeat the procedure, if necessary.

Show/hide table




Illustration 15	g00311283

Tighten the adjustment screw locknut.

Repeat Step 3 through Step 9 for each valve.

After all valves are adjusted for the TC compression stroke, remove the crankshaft timing pin. Rotate the flywheel by 360 degrees in the direction of normal crankshaft rotation. This will put No. 1 piston at TC exhaust stroke. Install the timing pin. Complete the adjustments for the cylinders that remain.

Valve Lash Adjustment for the Gas Admission Valve

Show/hide table

Table 7
Valve Lash Setting with the Engine Stopped
Gas Admission Valve	0.64 mm (0.025 inch)

Put the No. 1 piston at the TC position. Refer to "Finding the Top Center Compression Position for No. 1 Cylinder".

Show/hide table




Illustration 16	g00498237
Rocker arm with pin (1) 146-2742 Gas Inlet Valve Test Tool (2) Pin

Install the dial indicator into the 146-2742 Gas Inlet Valve Test Tool (1). Install the dial indicator onto the rocker base. If the rocker has a pin (2) in the side, align the tip of the dial indicator with the center of the pin.
Note: Make sure that the rocker arm is pressed to the left in order to indicate the maximum lash.

Show/hide table




Illustration 17	g00500314
Rocker arm with a counterbore (3) Counterbore

If the rocker arm has the counterbore (3), align the tip of the dial indicator with the center of the counterbore.

Show/hide table




Illustration 18	g00500316

Lift on the end of the rocker arm that has the adjusting screw. Zero the dial indicator.

Show/hide table




Illustration 19	g00500317

While you are firmly rotating the rocker arm in the opposite direction, push the rocker arm toward the exhaust valve rocker arm.

Read the gas admission valve lash on the dial indicator. If the lash is within specifications, remove the tooling and go to the next valve.

After each adjustment, tighten the nut for the adjustment screw to a torque of 30 ± 4 N·m (22 ± 3 lb ft). Check the valve lash again. Repeat the procedure, if necessary.

If the lash is not within specifications, loosen the adjusting locknut. While you are holding the rocker arm in the position from Step 5, turn the adjusting screw until the correct lash is seen on the dial indicator. Refer to Table 7 for the correct setting. Tighten and torque the locknut. Recheck the setting.

Perform the procedure for remaining valves.

After all valves are adjusted for the TC compression stroke, remove the crankshaft timing pin. Rotate the flywheel for 360 degrees in the direction of the normal crankshaft rotation. This will put No. 1 piston at the TC position for the exhaust stroke. Install the timing pin. Complete the adjustments for the cylinders that remain.

Crank Angle Sensor and Speed Sensors

Use the following procedure in order to adjust the mounting plate for the crank angle sensor and for the speed sensors.

Show/hide table




Illustration 20	g00498303
124-3349 Plate

While the engine is stopped, assemble the timing control for the crank angle sensor in hole (E). Turn the sensor until the sensor contacts the flywheel. Unscrew the sensor for 5/8 of a turn. Tighten the locknut to a torque of 45 ± 7 N·m (33 ± 5 lb ft). The correct clearance between the sensor and the flywheel is 0.55 to 0.83 mm (0.022 to 0.033 inch).

Install the crankshaft timing pin. Loosen the bolts for the sensor's mounting plate. Slide the plate in order to center the crank angle sensor over the hole in the flywheel. Tighten the bolts for the sensor's mounting plate.

Assemble the engine speed sensor in hole (C). Turn the sensor until the magnet contacts the ring gear tooth. Unscrew the sensor by 5/8 of a turn. Tighten the locknut to a torque of 45 ± 7 N·m (33 ± 5 lb ft). The correct clearance between the sensor and the flywheel is 0.55 to 0.83 mm (0.022 to 0.033 inch).

When the crankshaft is pinned and the crank angle sensor centered over the hole in the flywheel, assemble the timing control's speed sensor in either hole (A), (B) or (D). Choose the hole that provides the best alignment over the center of a ring gear tooth. Turn the sensor until the magnet contacts the ring gear tooth. Unscrew the sensor by 5/8 of a turn. Tighten the locknut to a torque of 45 ± 7 N·m (33 ± 5 lb ft). The correct clearance between the sensor and the flywheel is 0.55 to 0.83 mm (0.022 to 0.033 inch).

Remove the crankshaft timing pin.

Timing Calibration of the Caterpillar Ignition System (CIS)

Place the engine in "MAG CAL" mode by using the Digital Diagnostic Tool (DDT).

Use the Display Module to preset the CIS electronic control. Follow the instructions that are given in Special Instruction, REHS0190, "System Operation, Testing and Adjusting for the Caterpillar Ignition System".

Start the engine.

With the engine speed above 550 rpm, set the engine timing to 28 degrees BTC. For information that relates to adjustment of the engine timing, refer to Special Instruction, REHS0190, "System Operation, Testing and Adjusting for the Caterpillar Ignition System".