99298 Mercruiser NUT, (.500-20), TRANSOM PLATE SCREW

Recommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 1
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.
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. 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 4.
4. Clean the Fuel System
A. Following the instructions on the bottle, add Cat 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. Electronic Unit Injectors
A. Use the electronic service tool to perform the automatic "Cylinder Cutout Test". Refer to Troubleshooting, Service Tool Features for more information.
Note: If the compression test that was performed in Test Step 3 was satisfactory, the "Cylinder Cutout 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 Cutout 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 6.
6. 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 7.
Result: The fuel quality is not OK.
Repair: Replace the fuel. Verify that the repair eliminated the fault.
7. 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 8.
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.
8. Engine Accessory
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 9.
9. 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
Injectors
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 10.
Result: The valve train components are damaged.
Repair: Make the necessary repairs, Verify that the repair eliminated the fault.
10. 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 11.
11. 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).