28636 Mercruiser SCERW, COVER (3/4")

Probable Causes
Starting aids (if applicable)
Coolant temperature sensor
Engine speed/timing
Unit injectors
Flash file
Fuel supply
Component wear
Cooling systemRecommended Actions
Table 1
Troubleshooting Test Steps Values Results
1. Check the Starting Aids
A. Check for proper operation of the jacket water heater. Repair the jacket water heater or replace the jacket water heater.
B. Ensure that the ether canister is not empty or low. Replace the ether canister if the ether canister is empty or low. Refer to Troubleshooting, "Ether Injection System - Test".
Starting Aids
Result: The starting aids are OK.
Proceed to Test Step 2.
Result: The starting aids are NOT OK.
Repair: Repair or replace any damaged or worn components.
2. Check the Coolant Temperature Sensor
A. Use Cat® Electronic Technician (ET) to verify that the engine has exited cold mode.
B. Compare the coolant temperature from Cat ET to the coolant temperature that is obtained from the 6V-9130 Temperature Adapter (MULTIMETER). Ensure that the temperature readings are reasonable for the conditions that are present.
Coolant Temperature Sensor
Result: The coolant temperature sensor is OK.
Proceed to Test Step 3.
Result: The coolant temperature sensor is NOT OK.
Repair: Replace the coolant temperature sensor.
3. Check the Engine Speed/Timing
A. Check the calibration of the engine speed/timing sensor. Refer to Troubleshooting, "Engine Speed/Timing Sensor - Calibrate".
B. Verify that the timing of the crankshaft and camshaft drive gears are set with the proper orientation. Refer to Disassembly and Assembly for information that is related to the correct gear installation.
Engine Speed/Timing
Result: The engine speed/timing is OK.
Proceed to Test Step 4.
Result: The engine speed/timing is NOT OK.
Repair: Repair or replace any damaged or worn components.
4. Check the Unit Injectors
A. Perform the "Cylinder Cutout Test" on Cat ET to try to isolate any cylinders that may be misfiring. A misfiring cylinder could be related to an injector that is worn or in poor repair. Refer to Troubleshooting, "Injector Solenoid Circuit - Test".
B. Cut out each individual cylinder for 30 to 60 seconds. Verify that the smoke decreases.
Unit Injectors
Result: The unit injectors are OK.
Proceed to Test Step 5.
Result: The unit injectors are NOT OK.
Repair: Replace the unit injectors.
5. Check for the Correct Flash File
A. Verify that the correct flash file is installed.
Flash File
Result: The correct flash file is installed.
Proceed to Test Step 6.
Result: The correct flash file is NOT installed.
Repair: Download and install the correct flash file.
6. Check the Fuel Supply
A. Inspect the fuel system components.
B. Check the fuel pressure during engine cranking. Check the filtered fuel pressure. Refer to Systems Operation/Testing and Adjusting for the correct pressure values. If the fuel pressure is low, replace the fuel filters. If the fuel pressure is still low, check the following items: fuel transfer pump, fuel transfer pump coupling, and fuel pressure regulating valve.
C. Check the fuel quality. Low cetane fuel can create white smoke. If necessary, replace the fuel with a higher cetane fuel.
Note: Cold weather adversely affects the characteristics of the fuel. Refer to the Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold-weather operation.
Fuel Supply
Result: The fuel supply is OK.
Proceed to Test Step 7.
Result: The fuel supply is NOT OK.
Repair: Repair or replace any damaged or worn components.
7. Check for Component Wear
A. Check the engine for the following problems: Excessive valve wear, piston wear, ring wear, liner wear, and reduced compression pressure.
Wear
Result: The components are OK.
Proceed to Test Step 8.
Result: The components are NOT OK.
Repair: Repair or replace any damaged or worn components.
8. Check the Cooling System
A. Check for an internal coolant leak into the cylinder and/or the exhaust. Refer to Systems Operation/Testing and Adjusting for information on inspecting the cooling system.
Cooling System
Result: The cooling system is OK.
Return the engine to service.
Result: The cooling system is NOT OK.
Repair: Repair or replace any damaged or worn components.