Engine Has Mechanical Noise (Knock)
- Active codes and logged codes
- Electrical connections
- Fuel injection
- Fuel quality
- Proper lubrication
- Isolate the source of the noise.
- Valve train components
- Pistons and connecting rods
- Crankshaft
Note: The procedures have been listed in order of probability. Complete the procedures in order.
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| Troubleshooting Test Steps | Values | Results |
|---|---|---|
1. Active Codes and Logged Codes A. Establish communication between the electronic service tool and the Electronic Control Module (ECM). Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Download the "Warranty Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes. |
Codes |
Result: There are active codes. Repair: Troubleshoot any active codes before continuing with this procedure. Result: There are no active codes. Proceed to Test Step 2. |
2. Electrical Connections A. Check for the correct installation of the ECM J1/P1 and the J2/P2 connectors. Check for correct installation of the fuel injector connectors. |
Connectors |
Result: There are suspect connectors. Repair: Repair connectors that are suspect or replace connectors that are suspect. Perform the "Wiggle Test" on the electronic service tool. Result: There are no suspect connectors. Proceed to Test Step 3. |
3. Fuel Injection A. Perform the "Fuel System Verification Test" in the "Diagnostic Tests" under the "Diagnostics" menu. |
Fuel system verification test |
Result: The test was successful. Proceed to Test Step 4. Result: The test was not successful. Repair: Diagnose and repair the fault. Reset all active codes and clear all logged codes. Verify that the repair eliminated the fault. |
4. Fuel Quality A. Refer to Operation and Maintenance Manual for information on the correct characteristics of the fuel for the engine. If necessary, obtain a fuel analysis to confirm that the correct fuel is being used for the engine. Refer to Systems Operation, Testing, and Adjusting, "Fuel Quality - Test" for the correct procedure. |
Fuel |
Result: The fuel quality is OK. Proceed to Test Step 5. Result: The fuel quality is not OK. Repair: Replace the fuel. Verify that the repair eliminated the fault. |
5. Lubrication A. Check for sufficient lubrication of the valve components. B. Check for blocked oil passages. Oil passages must be clean. Clean any oil passages that are suspect. Refer to the Disassembly and Assembly for additional information. C. Inspect the engine oil filters for ferrous material. D. Obtain an oil analysis. Note: The analysis will contribute to a better understanding of oil contamination and the origin of the contamination. |
Lubrication |
Result: The oil passages are not blocked and the engine has sufficient lubrication. Proceed to Test Step 6. Result: The oil passages are blocked or the engine does not have sufficient lubrication. Repair: Make the necessary repairs, Verify that the repair eliminated the fault. |
6. Isolate the Source of the Noise A. If the source of the noise is an engine accessory, remove and inspect the suspect item. |
Engine accessory |
Result An engine accessory is the source of the noise. Repair: Repair and/or replace the engine accessory, if necessary. Result An engine accessory is not the source of the noise. Proceed to Test Step 7. |
7. Valve Train Components A. Check the valve lash. Refer to Troubleshooting, "Valve Lash Is Excessive". B. Check for damage to valve train components. Remove the valve cover from the suspect cylinders. Check the following items for damage: · Camshaft · Valve springs · Camshaft followers · Rocker shaft · Valve bridges · Pushrods Refer to Disassembly and Assembly for additional information. C. Check for valves that do not move freely. Remove the cylinder head and inspect the valves. Refer to Disassembly and Assembly for additional information. |
Valve train |
Result: The valve train components are not damaged. Proceed to Test Step 8. Result: The valve train components are damaged. Repair: Make the necessary repairs, Verify that the repair eliminated the fault. |
8. Pistons and Connecting Rods A. Inspect the pistons for damage and wear. B. Inspect the connecting rod bearings for damage and wear. |
Pistons and connecting rods |
Result: One or more components are worn or damaged. Replace any worn or damaged parts. Verify that the repair has eliminated the noise. Result: All components are OK. Proceed to Test Step 9. |
9. Crankshaft A. Inspect the crankshaft and the related components. Look for worn thrust plates and wear on the crankshaft. B. Inspect the connecting rod bearings and the bearing surfaces on the crankshaft. Make sure that the bearings are in the correct position. |
Crankshaft |
Result: The crankshaft or the related components are damaged or worn. Repair: Repair or replace any damaged parts. Verify that the repair eliminated the fault. Result: All components are OK. Contact the Dealer Solutions Network (DSN). |
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