Overhead Set ( )

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Cameron Lamb
5 years ago
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1 ISB, ISBe, ISBe4, QSB4.5, QSB5.9, and QSB6.7 (Common Rail Fuel System) Series Engines Service Manual Overhead Set ( ) General Information Overhead setting is only required at the interval specified in the appropriate Operation and Maintenance Manual/Owners Manual or when engine repairs cause removal of the rocker levers and/or loosening of the adjusting screws. Excessive valve lash prior to this can indicate an overhead set incorrectly from a previous repair, worn valve stems, crossheads, push rods, or rocker levers*. Loose rocker levers and the need to reset the valve clearance frequently can also indicate camshaft lobe or tappet wear. If an inspection of the rocker levers, valve stems, crossheads, and push rod does not show wear, then tappet and/or camshaft lobe wear can be suspected. Refer to Procedure in Section 1. Refer to Procedure in Section 4. Preparatory Steps WARNING Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) Page 1 of 7

2 battery cable first and attach the negative (-) battery cable last. Disconnect the batteries. Refer to Procedure in Section 13. Remove the rocker lever cover and gasket. Refer to Procedure in Section 3. Adjust All Applications Except Marine NOTE: Engine coolant temperature must be less than 60 C [140 F]. NOTE: For marine engines equipped with a TDC mark on the vibration damper, use the Adjust step for All Applications Except Marine. NOTE: For marine engines not equipped with a TDC mark on the vibration damper, use the Adjust step for Marine Applications. Use the barring tool, Part Number to rotate the crankshaft until the number 1 cylinder is at TDC. TDC can be determined by the following methods: For 3.9 L and 5.9 L Engines without EGR, align the crankshaft speed indicator ring on the front of the crankshaft so that the unpunched area of the crankshaft speed indicator ring is at the 12- o'clock position. If both number 1 cylinder rocker levers are loose, move to the following steps. If Page 2 of 7

both number 1 cylinder rocker levers are not loose, rotate the crankshaft 360 degrees. NOTE: The TDC indicator is on the vibration damper/crankshaft speed indicator ring. For all 4.5 L, 5.

If both number 1 cylinder rocker levers are loose, move to the following steps. If both number 1 cylinder rocker levers are not loose, rotate the crankshaft 360 degrees.

3 both number 1 cylinder rocker levers are not loose, rotate the crankshaft 360 degrees. NOTE: The TDC indicator is on the vibration damper/crankshaft speed indicator ring. For all 4.5 L, 5.9 L engines with EGR, and 6.7 L engines, align the vibration damper/crankshaft speed indicator ring so that the TDC indicator is at the 12-o'clock position. If both number 1 cylinder rocker levers are loose, move to the following steps. If both number 1 cylinder rocker levers are not loose, rotate the crankshaft 360 degrees. NOTE: If no TDC mark is present on either the vibration damper or the crankshaft speed indicator ring, align the large gap in the crankshaft speed indicator ring to the 5- o'clock position (2). The dowel pin could also be visible in the 9-o'clock position (1). Check that both number 1 cylinder rocker levers are loose. If they are not loose, rotate the crankshaft 360 degrees and recheck. With the engine in this position, lash can be measured on the following rocker levers: (E = exhaust, I = Intake) Four-cylinder 1I, 1E, 2l, and 3E: Six-cylinder 1I, 1E, 2I, 3E, 4I, and 5E. Page 3 of 7

Lash Check Limits mm in Intake 0.152 MIN 0.006 0.381 MAX 0.015 Exhaust 0.381 MIN 0.015 0.762 MAX 0.

ranges. NOTE: The clearance is correct when some resistance is felt when the feeler gauge is slipped between the crosshead and the rocker lever socket.

4 Lash Check Limits mm in Intake MIN MAX Exhaust MIN MAX NOTE: Checking the overhead setting is usually performed as part of a troubleshooting procedure, and resetting is not required during checks as long as the lash measurements are within the above ranges. NOTE: The clearance is correct when some resistance is felt when the feeler gauge is slipped between the crosshead and the rocker lever socket. Measure lash by inserting a feeler gauge between the crosshead and the rocker lever socket. If the lash measurement is out of specification, loosen the locknut, and adjust the lash to nominal specifications. Valve Lash Specifications (Nominal) mm in Intake Exhaust Tighten the locknut and measure the lash again. Torque Value: 24 n.m [212 inlb ] Using barring tool, Part Number , rotate the crankshaft 360 degrees. Following the same steps and specifications as previously stated, measure lash for the following rocker levers: (E = exhaust, I = Intake) Page 4 of 7

Four-cylinder 2E, 3I, 4E, and 4I: Six-cylinder 2E, 3I, 4E, 5I, 6I, and 6E. Reset if out of specification. Marine Applications NOTE: The engine coolant temperature must be less than 60 C [140 F].

5 Four-cylinder 2E, 3I, 4E, and 4I: Six-cylinder 2E, 3I, 4E, 5I, 6I, and 6E. Reset if out of specification. Marine Applications NOTE: The engine coolant temperature must be less than 60 C [140 F]. NOTE: For marine engines equipped with a TDC mark on the vibration damper, use the Adjust step for All Applications Except Marine. NOTE: For marine engines not equipped with a TDC mark on the vibration damper, use the Adjust step for Marine Applications. Use barring tool, Part Number , to rotate the crankshaft until the number 1 cylinder is at top-dead-center (TDC). To determine TDC when setting the overhead on marine engines, rotate the crankshaft until either cylinder Number 1 or cylinder Number 6 exhaust and intake rocker levers are both loose. NOTE: If a more precise way is needed to determine TDC, remove the injector from cylinder Number 1. Use a rod with a dial indicator to find TDC. With the engine in this position, lash can be adjusted on the following rocker levers: (E = exhaust, I = intake) Four-cylinder - 1I, 1E, 2I, and 3E Six-cylinder - 1I, 1E, 2I, 3E, 4I, and 5E. Page 5 of 7

6 NOTE: The clearance is correct when some resistance is felt when the feeler gauge is slipped between the crosshead and the rocker lever socket. Loosen the locknut and adjust the lash to nominal specifications. Valve Lash Specifications (Nominal) mm in Intake Exhaust Tighten the locknut and measure the lash again. Torque Value: 24 n.m [212 inlb ] Use barring tool, Part Number , to rotate the crankshaft 360 degrees. Follow the same steps and specifications as previously stated to continue adjusting the valve lash. (E = exhaust, I = intake) Four-cylinder - 2E, 3I, 4E, and 4I Six-cylinder - 2E, 3I, 4E, 5I, 6I, and 6E. Finishing Steps WARNING Page 6 of 7

7 Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last. Install the gasket and rocker lever cover. Refer to Procedure in Section 3. Connect the batteries. Refer to Procedure in Section 13. Operate the engine and check for leaks. Last Modified: 11-Feb-2009 Page 7 of 7

https://quickserve.cummins.com/qs2/pubsys2/xml/en/procedures/40/ tr.html

Page 1 of 7 NOTE: The timing pin is used to accurately locate TDC for setting the overhead. The timing pin is typically located below the fuel pump. for front gear train engines, in the front gear housing