COLLAR 3G8887 - Caterpillar

Probable Causes
Valve lash setting is not at factory specifications.
Worn rocker arms
Worn valve springs or broken valve springs
Bent pushrods
Worn camshaft
Valve seat wearRecommended Actions
Table 1
Troubleshooting Test Steps     Values     Results    
1. Valve Lash Setting
A. Check the engine valve lash. If necessary, adjust the engine valve lash. Refer to Systems Operation/Testing and Adjusting for information on adjusting the engine valve lash.
   
Valve Lash    
Result: The valve lash is set to specifications.
Return the unit to service.
Result: The valve lash cannot be set to specifications.
Proceed to Test Step 2.    
2. Rocker Arms
A. Inspect rocker arms for pitting or spalling on the roller.
B. Check the rocker arm for a missing button.
   
Rocker Arms    
Result: The rocker arms are damaged.
Repair: Replace parts, if necessary. If the symptom remains, proceed to Test Step 3.
If the problem has been corrected, return the unit to service.
Result: The rocker arms are not damaged.
Proceed to Test Step 3.
   
3. Valve Springs
A. Check for cracked valve springs or broken valve springs.
   
Valve Springs    
Result: The valve springs are not broken or cracked.
Proceed to Test Step 4.
Result: The valve springs are broken or cracked.
Repair: Replace parts, if necessary. If the symptom remains, Proceed to Test Step 4.
If the problem has been corrected, return the unit to service.
   
4. Pushrods
A. Check the pushrods for wear and straightness.
B. Roll the pushrods on a flat surface in order to determine the straightness of the rod.
   
Pushrods    
Result: The pushrods are not worn or bent.
Proceed to Test Step 5.
Result: The pushrods are worn or bent.
Repair: Replace parts, if necessary. If the symptom remains, Proceed to Test Step 5.
If the problem has been corrected, return the unit to service.
   
5. Camshaft
A. Remove the camshaft in order to inspect the camshaft.
B. Inspect the camshaft for large grooves.
C. Measure the camshaft in order to determine if the camshaft is in specifications. Refer to Reuse and Salvage Guidelines for the correct measurements.
   
Camshaft    
Result: The camshaft measured within specifications.
Proceed to Test Step 6.
Result: The camshaft did not measure within specifications.
Repair: Make the necessary repairs, If the symptom remains, proceed to Test Step 6. If you replace the camshaft, replace the valve lifters.
If the problem has been corrected, return the unit to service.
   
6. Cylinder Head
A. Remove the cylinder head. Refer to the Reuse and Salvage Guidelines for the reusability specifications.
B. Inspect the piston and valve for damage.
C. Inspect the valve seat for wear.
   
Engine Components    
Result There are worn or damaged engine components.
Repair: Replace parts, if necessary. Check the Reuse and Salvage Guidelines for the reusability of existing engine components.
   Contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).