Possible reasons
• Diagnostic code
• Fuel quality
• Valve train components
• Low compression (cylinder pressure)
• Fuel injector
• Pistons and connecting rods
Recommended actions Note: The steps are listed below in probabilistic order. Complete these steps in order.
1. Diagnostic code
A. Establish communication between the electronic service tool and the electronic control module (ECM).
B. Before performing any troubleshooting or clearing any diagnostic codes, download the warranty with bar chart reports and products Product status report. NOTE: If troubleshooting assistance is required, the Dealer Solutions Network (DSN) will need the downloaded information.
C. Use an electronic service tool to check for active or logged codes.
Result: A diagnostic trouble code is activated or logged.
Repair: Diagnose and troubleshoot activated or logged codes.
Result: No diagnostic trouble code is activated or logged. Go to test step 2.
Result: Poor fuel quality.
Repair: Drain the fuel system and replace the fuel filter. Refer to the Operation and Maintenance Manual, “Fuel System Prefilter (Fuel Water Separator) Element – Replacement” and the Operation and Maintenance Manual, “Fuel System Filter – Replacement”.
Fill the fuel system with fuel that meets the specifications in the Operation and Maintenance Manual, “Fluid Recommendations”. Prime the fuel system. Refer to the Operation and Maintenance Manual, “Fuel System – Charging”. Verify that this step eliminates the noise.
Result: Fuel quality is normal. Go to test step 3.
3. Valve train components
A. Check valve clearance. See Troubleshooting, “Excessive Valve Clearance”.
B. Check the valve train components for damage. Remove the valve cover from the engine. Check the following components for damage: · Valve spring · Rocker shaft · Valve bridge · Push rod · Camshaft follower · Hydraulic lift For more information, refer to Disassembly and Assembly.
4. Low compression (cylinder pressure) A. Perform compression testing. See System Operation, Testing, and Tuning, “Compression – Test”.
Result: Compression test results exceeded specifications.
Repair: Investigate the cause and eliminate any faults.
NOTE: Possible causes of low compression pressure are listed
below: ·
The glow plug is loose
· Piston failure
· Piston ring failure
· Bore wear
· Valve wear
· Cylinder head gasket failure
· Cylinder head damaged
Results: The results of the compression test were normal. Continue to test step 5.
5. Electronic unit injector A. Use an electronic service tool to perform an automatic “cylinder cutoff test.”
NOTE: If the compression test performed in Test Step 4 is as expected, the “Breakout Test” will identify any faulty injectors. Result: Indicates a faulty injector. Repair: Remove any faulty electronic unit injector. Refer to Disassembly and Assembly, “Electronic Unit Injector – Disassembly”. Install new electronic unit injectors. Refer to Disassembly and Assembly, “Electronic Unit Injector – Installation”. Repeat the automatic “cylinder cutoff test”. If the fault is still apparent, remove the replacement electronic unit injector and install the original electronic unit injector. See Disassembly and Assembly, “Electronic Unit Injector – Disassembly” and Disassembly and Assembly, “Electronic Unit Injector – Assembly”. Result: All injectors are normal. Go to test step 6.
6. Piston and connecting rod A. Check the piston for damage and wear. B. Check the connecting rod bearings for damage and wear. Result: At least one component is worn or damaged. Repair: Replace any worn or damaged parts. Eliminate the noise after confirming repairs. Result: All parts are normal If the problem persists, contact Dealer Solutions Network (DSN).
