864290 Mercruiser NUT

Troubleshooting Problems
Problem 1: Loud Combustion Noise
Probable Cause
Poor Quality Or Water In The Fuel - Find the source of contamination. Remedy the suspect source.The Wrong Timing Position Sensor Calibration - Refer to Troubleshooting, "Timing Calibration".Problem 2: Fuel Consumption Too High
Probable Cause
Poor Quality Or Water In The Fuel - Find the source of contamination. Remedy the suspect source.Fuel System Leaks - Inspect the fuel system for leaks. As needed, make repairs or replacements.Excess Idle Time - The engine should be shut off when the engine is not active.Fuel And Combustion Noise (knock) - Refer to Troubleshooting, "Engine Misfires, Runs Rough, or Is Unstable" for more information.Wrong Timing Position Sensor Calibration - Refer to Troubleshooting, "Timing Calibration" for more information.Problem 3: Too Much Black Or Gray Smoke
Probable Cause
Not Enough Air For Combustion - Check for a plugged air cleaner element or for blockage in the air lines. Refer to Testing And Adjusting for the procedures to check inlet manifold pressure and aftercooler core leakage.Wrong Timing Position Sensor Calibration - Refer to Troubleshooting, "Timing Calibration".Problem 4: Too Much White Smoke
Probable Cause
Engine Misfires Or Runs Rough - Refer to "Problem 3: Too Much Black Or Gray Smoke". Refer to Troubleshooting, "Engine Misfires, Runs Rough, or is Unstable" for more information.Wrong Timing Position Sensor Calibration - Refer to Electronic Troubleshooting, "Timing Calibration" for more information.Coolant In The Combustion System - White smoke can also be caused from the following problems.
Coolant in the combustion chamber
A cracked cylinder head
A cracked cylinder liner
A faulty cylinder head gasketProblem 5: Too Much Blue Smoke
Probable Cause
Too Much Oil In The Engine - Do not put too much oil in the crankcase. If the oil level in the crankcase increases during engine operation, check for fuel in the crankcase.Failed Turbocharger Oil Seal - Check the inlet manifold and the aftercooler core for oil. The turbocharger should be repaired or replaced.Worn Valve Guides - Refer to Specifications, "Cylinder Head Valves" for the maximum permissible wear of the valve guides.Worn Piston Rings - Worn piston rings and/or cylinder walls can be the cause of blue smoke and a loss of compression. Make a visual inspection of the cylinder walls and the piston rings. If necessary, measure the cylinder walls and the piston rings. Refer to Specifications, "Piston and Rings" for the specifications of the piston ring. Refer to Specifications, "Cylinder Liner" for the specifications of the cylinder liner.Problem 6: Engine Has Low Oil Pressure
Probable Cause
Low Engine Oil Level - Check the engine oil level and fill to the proper level.Oil Leaks - Check for a loose oil filter or for loose oil supply lines.Dirty Oil Filter Or Cooler - Check the operation of the bypass valve for the filter. As required, install new oil filter elements. Clean the oil cooler or install a new oil cooler. Remove the dirty oil and fill the engine with clean oil to the correct level.Diesel Fuel In Lubricating Oil - Find the location of the diesel fuel leak into the lubrication oil. Make repairs, as needed. Remove any oil that contains diesel fuel. Install new oil filters and fill the engine with clean oil to the correct level.Too Much Clearance Between Rocker Arm Shaft And Rocker Arms - Check for the correct lubrication in the valve train. Install new parts, as needed.Suspect Suction Tube for the Oil Pump - Replacement of the Tube is needed.The Relief Valve For The Oil Pump Does Not Operate Correctly. - Clean the valve and the housing. Install new parts, as required.The Oil Pump Has A Defect. - Make a repair or a replacement of the oil pump, as needed.Too Much Clearance Between Crankshaft And Crankshaft Bearings - Inspect the bearings and the crankshaft journals. Make a repair or a replacement, as needed.Too Much Bearing Clearance For Idler Gear - Inspect the bearings and make replacements, as needed.Piston Cooling Jets Are Not Installed - Install the piston cooling jets.Faulty Oil Pressure Gauge - Replace the oil pressure gauge.Problem 7: Engine Overheating
Probable Cause
Low Coolant Level - A sufficient amount of coolant will not go through the engine and the radiator if the coolant level is too low. This lack of coolant will not take enough heat from the engine. There will be insufficient radiator coolant flow. The heat will not be released into the cooling air. Once the engine has cooled, make sure that the coolant can be seen at the low end of the fill neck that is on the radiator top tank.Faulty Temperature Gauge - A temperature gauge which does not work correctly will not show the correct temperature. A temperature gauge can show that the coolant temperature is too hot. This can happen even when other conditions are normal. Install a gauge that is in working order or check the cooling system with the 4C-6500 Digital Thermometer.Dirty Radiator - Check the radiator for debris between the fins of the radiator core which prevents free air flow through the radiator core.Loose Belts - Tighten the belts according to the Belt Tension Chart. Refer to Specifications, "Belt Tension Chart" for further information.Suspect Hoses - Suspect hoses with leaks can normally be seen. Hoses that have no visual leaks can collapse during operation. This will cause a restriction in the flow of coolant. Hoses become soft and/or get cracks after a period of time. Refer to Operation and Maintenance Manual for the frequency for changing hoses. The inside of the hose can deteriorate, and the loose particles can cause a restriction in the flow of coolant.Shunt Line Restriction - A restriction of the shunt line from the radiator top tank to the engine water pump will cause a reduction in the water pump efficiency. A shunt line that is not correctly installed will also cause a reduction in the water pump efficiency. The result will be low coolant flow and overheating.Shutters Not Opening Correctly - Check the opening temperature of the shutters. Also verify that the fan control switches or the viscous fans are operating correctly.Faulty Water Temperature Regulator (Thermostat) - Above