21422767 Volvo.Penta Belt tensioner

Probable Causes
Intake air temperature
Inlet air restriction
Engine overload
Exhaust restriction
Deposits or leaksRecommended Actions
Table 1
Troubleshooting Test Steps    Values    Results    
1. Check for High Intake Air Temperature
Note: A one degree increase in the intake manifold temperature will increase the exhaust temperature by approximately three degrees.
A. Refer to Troubleshooting, "Intake Manifold Air Temperature Is High" for additional information.
   
Temperature
   
Result: The intake manifold air temperature is OK.
Proceed to Test Step 2.
Result: The intake manifold air temperature is NOT OK.
Repair: Determine the cause of the high intake manifold air temperature and correct the problem.
If the problem is not resolved, proceed to Test Step 2.
   
2. Check for a Restriction in the Inlet Air System
Note: Inlet air restriction can cause uneven exhaust port temperatures. Cylinders at the front half of the engine may have exhaust port temperatures that are lower than the exhaust port temperatures for the cylinders at the rear half of the engine by
10 to 20 °C (18 to 36 °F).
A. Check the air filter restriction indicator, if equipped. Refer to the Operation and Maintenance Manual for additional information.
B. Measure the inlet air restriction for each turbocharger. Refer to Troubleshooting, "Inlet Air Is Restricted" for additional information.
   
Restriction
   
Result: The inlet air restriction is OK .
Proceed to Test Step 3.
Result: The inlet air restriction is NOT OK. An imbalance in the system is discovered.
Repair: Repair or replace damaged inlet air system components. Equalize the inlet air restriction for each of the turbochargers.
If the problem is not resolved, proceed to Test Step 3.
   
3. Check for Engine Overload
Note: When the load that is applied to the engine is too large, the engine will run in the lug condition. When the engine is running in the lug condition, engine rpm does not increase with an increase of fuel.
   
Load
   
Result: The engine is not being overloaded.
Proceed to Test Step 4.
Result: The engine is being overloaded.
Repair: Reduce engine load to an acceptable limit.
If the problem is not resolved, proceed to Test Step 4.
   
4. Check for a Restriction in the Exhaust System
Note: A restriction of the exhaust can cause high cylinder temperatures.
A. Measure the exhaust restriction during engine operation with a load. For data that is specific to your engine, refer to the Technical Marketing Information (TMI).
   
Restriction
   
Result: The exhaust restriction measurement is OK.
Proceed to Test Step 5.
Result: The exhaust restriction measurement is NOT OK.
Repair: Repair or replace damaged exhaust system components.
If the problem is not resolved, proceed to Test Step 5.
   
5. Check for Heavy Buildup of Deposits in the Cylinder or Internal Oil Leaks
A. Use a borescope to inspect the cylinders. Look for the following conditions:
- Deposits on the valve seats
- Deposits on the valve faces
- Deposits on the cylinder walls that are above the upper limit of the piston stroke
- Signs of internal oil leaks
   
Deposits and Leaks
   
Result: The cylinder check is NOT OK.
Repair: Repair or replace damaged components.
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).