879680 Mercruiser GASKET-CYLINDER HEAD, REAR

Remove Injectors: Always make sure that injectors are not damaged during removal as the valve tips can easily be damaged. Install Injectors: Make sure injector/cylinder head bore and seat are clean. See Testing And Adjusting for injector seal installation. If nozzle body or needle valve are worn or damaged, the nozzle and valve must be replaced.1. Engine Will Not Start2. Engine Starts, Runs For A Few Moments, Then Stops3. Engine Misfires Or Runs Rough4. Engine Runs Evenly But Loses Power5. Engine Does Not Have Enough Power6. Too Much Vibration7. Combustion Noise8. Valve Compartment Noise9. Oil In Cooling System10. Engine Knock11. Little Rocker Movement Arm And Too Much Valve Clearance12. Valve Spring Lock13. Oil At The Exhaust14. Little Or No Valve Clearance15. Engine Has Early Wear16. Coolant In Lubrication Oil17. Too Much Black Or Gray Smoke18. Too Much White Or Blue Smoke19. Engine Has Low Oil Pressure20. Engine Uses Too Much Lubrication Oil21. Engine Coolant Is Too Hot22. Exhaust Temperature Is Too HighTroubleshooting Problems
Problem 1: Engine Will Not Start Probable Cause:1. Fuel Stop Control In NO FUEL Position: Turn control to RUN position.2. Fuel Shutoff Solenoid Is Defective: Replace solenoid.3. Fuel Tank Is Low, Air In Fuel System: Fill fuel tank, bleed air from fuel system.4. Fuel Lift Pump Is Defective: Remove lift pump; repair or replace as necessary.5. Fuel Filter, Water Separator Or Lines Are Restricted: Check Fuel supply line, filter and water separator.6. Fuel Injection Pump Operation Not Correct: Repair or replace fuel injection pump.7. Injectors Are Defective: Repair or replace injectors.8. Cold Start Heater Is Defective: Check, replace if necessary.9. Valve Clearance and/or Pump Timing Not Correct: Check, adjust if necessary.10. Weak Compression: With weak compression, starting may be difficult in warm weather, but in cold weather the engine may refuse to start. The number of causes are great, worn liners, piston rings, leakage of valves, etc. Problem 2: Engine Starts, Runs For A Few Moments Then Stops Probable Cause:1. Fuel Supply Line Or Filter Restricted: Repair or replace as necessary.2. Fuel Lift Pump Operation Not Correct: Check output of pump, repair or replace.3. Restriction In The Inlet Or Exhaust System: Check and remove restrictions.4. Air In The Fuel System: Find the air leak in the fuel system and correct it. Bleed the air from the fuel system. Problem 3: Engine Misfires Or Runs Rough Probable Cause:1. Fuel Pressure Is Low: Make sure fuel tank has enough fuel. Look for leaks or bad bends in the fuel supply line. Check outlet pressure of the fuel lift pump. See Specifications.2. Air In The Fuel System: Find the air leak in the fuel system and correct it. Bleed the air from the fuel system.3. Injector Is Defective: Run engine at the rpm that gives maximum misfiring or rough running. Then, loosen a fuel line nut on the injection line for each cylinder, one at a time. Find the cylinder where loosening the fuel line nut does not change the way the engine runs. Test the fuel injector for that cylinder. Install new parts where needed.4. Valve Clearance And/Or Pump Timing Not Correct: Check, adjust if necessary.5. Fuel Injection Pump Operation Is not Correct: Repair or replace if necessary.6. Moisture In The Fuel System: Locate, remove and install new clean fuel. Problem 4: Engine Runs Evenly But Loses Power Probable Cause:1. Injectors Need Repair: Repair or replace as necessary.2. Fuel Injection Pump Operation Not Correct: Repair or replace as necessary.3. Air Cleaner Restriction: Clean or replace air cleaner.4. Fuel Injection Pump Timing Not Correct: Check and make correction.5. Fuel Lift Pump Installed With Camshaft Lobe On Maximum Lift: Install fuel lift pump with camshaft lobe on minimum lift and tighten bolts evenly.6. Loss Of Compression: Engine needs repairs. Problem 5: Engine Does Not Have Enough Power Probable Cause:1. Bad Quality Fuel: Remove the fuel from the fuel tank. Install new filter element. Put a good grade of clean fuel in the fuel tank.2. Fuel Pressure Is Low: Make sure there is fuel in the fuel tank. Look for leaks or bad bends in the fuel line between fuel tank and fuel lift pump. Look for air in the fuel system. Check outlet pressure of the fuel lift pump. See Specifications.3. Air In The Fuel System: Refer to Problem 3.4. Governor Control Linkage Not Adjusted Properly: Adjust linkage for full travel. Install new parts for those that are damaged or defective.5. Wrong Valve Clearance: Adjust according to Specifications.6. Fuel Injection Nozzle Is Defective: Refer to Problem 3.7. Fuel Injection Pump Timing Not Correct: Check and correct. Problem 6: Too Much Vibration Probable Cause:1. Loose Pulley Bolt(s): Tighten the bolt(s).2. Pulley Is Defective: Install a new pulley.3. Engine Supports Are Loose, Worn Or Are Defective: Tighten all mounting bolts. Install new components if necessary.4. Misfires Or Runs Rough: Refer to Problem 3. Problem 7: Combustion Noise Probable Cause:1. Bad Quality Fuel: Remove the fuel from the fuel tank. Install a new filter element. Put a good grade of clean fuel in the tank.2. Fuel Injection Nozzle Is Defective: Refer to Problem 3. Problem 8: Valve Compartment Noise Probable Cause:1. Broken Valve Spring(s) Or Locks: Install new parts as necessary. Broken locks can cause the valve to slide into the cylinder. This will cause a lot of damage.2. Loose Bolts Or Nuts Holding Rocker Arm Assembly: Tighten the bolts or nuts.3. Too Much Valve Clearance: Adjust according to Specifications. Problem 9: Oil In Cooling System Probable Cause:1. Head Gasket Is Defective: Install a new head gasket.2. Engine Oil Cooler (T4.236) Is Defective: Replace engine oil cooler.3. Transmission Cooler Is Defective: Replace transmission cooler. Problem 10: Engine Knock Probable Cause:1. Main Bearing Failure: Inspect the main bearings and bearing surface of the crankshaft. Install new parts where necessary.2. Connecting Rod Bearing Failure: Inspect the connecting rod bearings and the bearing surface of the crankshaft. Install new parts where necessary.3. Crankshaft Is Damaged: Replace the crankshaft. Clean the engine thoroughly.4. Broken Camshaft: Replace the camshaft. Clean engine thoroughly. Problem 11: Little Rocker