MOUNT 1388862 - Caterpillar

Use this procedure to troubleshoot a problem with excessive valve lash.Probable Causes
Valve lash
Lifters
Rotocoils
Rocker arms
Valve springs
Pushrods
Worn engine components
CamshaftRecommended Actions
Table 1
Troubleshooting Test Steps Values Results
1. Check the Valve Lash
Note: The valve lash can affect the performance of the engine.
Valve Lash
Result: The valve lash is OK.
Proceed to Test Step 2.
Result: The valve lash is NOT OK.
Repair: Reset the valve lash. Refer to Testing and Adjusting, "Valve Lash - Adjust" for additional information.
If the problem is not resolved, proceed to Test Step 2.
2. Check the Condition of the Lifters
A. Inspect the lifters for the following:
- Pitting,
- Spalling
- Excessive wear on the rollers
Lifters
Result: The lifters are OK.
Proceed to Test Step 3.
Result: The lifters are NOT OK.
Repair: Repair or replace damaged components.
If the problem is not resolved, proceed to Test Step 3.
3. Inspect the Condition of the Rotocoils
A. Check for excessive wear and/or damage.
Rotocoils
Result: The rotocoils are in OK.
Proceed to Test Step 4.
Result: The rotocoils are NOT OK.
Repair: Repair or replace damaged rotocoils.
If the problem is not resolved, proceed to Test Step 4.
4. Inspect the Rocker Arms and Shafts
A. Inspect the following rocker arm components for damage and wear:
- Adjustment screw and button.
- Pushrod ball
- Rocker arm shaft bearing
B. Inspect the condition of the rocker arm shaft mounting assembly.
C. Inspect the condition of lifter bridge assembly.
Rocker Arms
Result: The rocker arm components are OK.
Proceed to Test Step 5.
Result: The rocker arm components are NOT OK.
Repair: Repair or replace damaged rocker arms components.
If the problem is not resolved, proceed to Test Step 5.
5. Inspect the Valve Springs for Damage
Valve Springs
Result: The valve springs are OK.
Proceed to Test Step 6.
Result: The valve springs are NOT OK.
Repair: Repair or replace damaged springs.
If the problem is not resolved, proceed to Test Step 6.
6. Check for Bent or Damaged Pushrods
A. Check the pushrods for wear and straightness.
Pushrods
Result: The pushrods are OK.
Proceed to Test Step 7.
Result: The pushrods are NOT OK.
Repair: Replace the worn or bent pushrods.
If the problem is not resolved, proceed to Test Step 7.
7. Inspect the Cylinder Head and Other Combustion Chamber Components for Damage
A. Remove the cylinder head for the affected cylinder.
B. Inspect the piston and valves for damage.
C. Inspect the valve seats for wear.
Damaged or Worn Engine Components
Result All engine components are in good repair.
Proceed to Test Step 8.
Result: There are worn or damaged engine components.
Repair: Repair or replace the worn or damaged engine components.
If the problem is not resolved, proceed to Test Step 8.
8. Inspect and Measure the Camshaft
A. Inspect the lobes of the camshaft for large grooves, scuffing, and wear.
B. Measure the camshaft lobes for lift and duration.
Camshaft
Result: The camshaft measurements are not within specifications.
Repair: Replace affected camshaft segment.
Verify that the repair eliminated the problem.
If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).