20555061 Volvo.Penta Hex. socket screw

Probable Causes
Vibration damper/front pulley (if equipped)
Engine supports
Driven equipment
Fuel system cleaning required
Low compression (cylinder pressure)
Electronic unit injectors
Individual malfunctioning cylinderRecommended Actions
Note: When performing the following procedure, do not stand near the engine. The vibration may indicate an imminent component failure.Note: Complete the procedure in the order in which the steps are listed.
Table 1
Troubleshooting Test Steps Values Results
1. Vibration Damper/Front Pulley (If Equipped)
A. Check the vibration damper for damage.
B. Make sure the vibration damper/front pulley is secure.
Mounts
Coupling
Vibration damper
Result: The vibration damper is damaged.
Repair: Replace the vibration damper/front pulley.
Result: The vibration damper is loose.
Repair: Tighten the securing nut to the correct torque.
Result: The vibration damper is OK.
Proceed to Test Step 2.
2. Engine Supports
A. Inspect the mounts and the brackets when running the engine through the speed range. Look for mounts and brackets that are loose and/or broken.
B. Check the alignment of the following before operating the engine under load for any length of time:
Mounts
Coupling
Engine supports
Result: The mounts and brackets are loose and/or broken.
Repair: Replace the mounts and brackets that are loose and/or broken.
Result: The mounts and brackets are not loose and/or broken.
Proceed to Test Step 3.
3. Driven Equipment
A. Inspect the mounting bolts for the driven equipment. Inspect the alignment and the balance of the driven equipment.
B. Inspect the coupling.
Driven equipment
Result The driven equipment and the alignment are not OK.
Repair: Repair or replace the driven equipment.
Result: The driven equipment and the alignment are OK.
Proceed to Test Step 4.
4. Clean the Fuel System
A. Following the instructions on the bottle, add Caterpillar Fuel System Cleaner 343-6210 to the fuel tank.
Electronic Unit Injectors
Result: Performance should be restored within 2-3 hours.
Return the unit to service, the fuel system will be cleaned during operation.
Result: Performance is not restored within 2-3 hours.
Proceed to Test Step 5.
5. Low Compression (Cylinder Pressure)
A. Perform a compression test. Refer to Systems Operation, Testing, and Adjusting, "Compression - Test".
Cylinder compression
Result: The results of the compression test are outside the specifications.
Repair: Investigate the cause and rectify any faults.
Note: Possible causes of low compression are shown in the following list:
Loose glow plugs
Faulty piston
Faulty piston rings
Worn cylinder bores
Worn valves
Faulty cylinder head gasket
Damaged cylinder head
Result: The results of the compression test are OK.
Proceed to Test Step 6.
6. Electronic Unit Injectors
A. Use the electronic service tool to perform the automatic "Cylinder Cut Out Test".
Note: If the compression test that was performed in Test Step 3 was satisfactory, the "Cylinder Cut Out Test" will identify any faulty injectors.
Electronic Unit Injectors
Result: A faulty injector is indicated.
Repair: Remove any faulty electronic unit injectors. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove".
Install new electronic unit injectors. Refer to Disassembly and Assembly, "Electronic Unit Injector - Install".
Repeat the automatic "Cylinder Cut Out Test". If the fault is still apparent, remove the replacement electronic unit injector and install the original electronic unit injector. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove" and Disassembly and Assembly, "Electronic Unit Injector - Install".
Result: All injectors are OK.
Proceed to Test Step 7.
7. Individual Malfunctioning Cylinders
A. With the engine speed at a fast idle, use the electronic service tool to perform the manual "Cylinder Cut Out Test".
As each cylinder is cut out, listen for a change in the sound from the engine. When a cylinder is cut out, there should be a noticeable change in the sound of the engine.
If a change in the sound of the engine is not noted, the isolated cylinder is not operating under normal conditions. If the isolation of a cylinder results in a change in the sound that is less noticeable, the cylinder may be operating below normal performance.
Cylinders
Result: The test indicates a faulty cylinder.
Repair: Investigate the cause of the fault on any cylinder that is not operating. Investigate the cause of the fault on any cylinder that is operating below normal performance.
Result: The test indicates that all cylinders are OK.
Contact the Dealer Solutions Network (DSN).