Section 15.2
General Troubleshooting
The tables that follow are designed to identify the causes of common problems and suggest further checks and appropriate remedies. When technical support is necessary, it is addressed in the table.
Note: Resolve all electronic diagnostic codes prior to performing mechanical checks.
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Problem - The Engine Will Not Crank |
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Cause |
Remedy |
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The batteries are damaged or weak. |
Test the batteries. Replace them, if needed. |
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The ignition switch is damaged. |
Replace the ignition switch. |
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The battery cables are damaged and/or corroded. |
Replace the battery cables. |
|
The starter is damaged and/or worn. |
Replace the starter. |
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The clutch or transmission is damaged. |
Refer to OEM guidelines. |
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There is internal damage to the engine. |
Repair the internal damage. |
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Problem—The Engine Turns Over Slowly |
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Cause |
Remedy |
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The batteries are damaged or weak. |
Test the batteries. Replace them, if needed. |
|
The ignition switch is damaged. |
Replace the ignition switch. |
|
The battery cables are damaged and/or corroded. |
Replace the battery cables. |
|
The starter is damaged and/or worn. |
Replace the starter. |
|
The engine oil does not meet the correct specifications. |
Change the engine oil, using the correct type of oil. |
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The transmission fluid does not meet the correct specifications. |
Change the transmission fluid, using the correct type of fluid. |
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Problem—The Engine Cranks, But Won't Start |
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Cause |
Remedy |
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The batteries are damaged or weak. |
Test the batteries. Replace them, if needed. |
|
The cranking speed is slow. |
Inspect the starter. Replace if needed. |
|
No intake air preheater is installed, and it is too cold to start without one. |
Install an intake air preheater. |
|
The intake air preheater is malfunctioning. |
Check the intake air preheater, and replace it, if necessary. |
|
The camshaft TDC sensor and/or the crank angle position sensor are out of adjustment. |
Push both sensors into their holes as far as they will go. If this does not solve the problem, replace the sensor(s). |
|
The camshaft TDC sensor and/or the crank angle position sensor are damaged. |
Replace the camshaft TDC sensor and/or the crank angle position sensor. |
|
There is air in the fuel system. |
Check the fuel lines for leaks. Bleed the fuel system and start the engine according to the instructions in the service manual. |
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The air filter is clogged. |
Clean or replace the air filter. |
|
The fuel filter is clogged. |
Replace the filter element. |
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The exhaust brake valve is malfunctioning. |
Repair or replace the exhaust brake valve. |
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The valves are not adjusted properly. |
Check the valve lash. |
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There are other problems in the fuel system. |
Check the fuel system. |
|
Problem—The Engine Starts Only After Cranking for a Long Time |
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Cause |
Remedy |
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The fuel tank is low or empty. |
Add fuel and bleed the fuel system, if necessary. |
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There are leaks in the fuel lines. |
Check the fuel lines for leaks and repair them, if necessary. |
|
The fuel filter is clogged. |
Replace the filter element. |
|
The fuel line, the fuel pre-filter, or the screen in the fuel tank is blocked. |
Clean and bleed the system. Check the fuel lines and filters. Repair or replace as necessary. |
|
The camshaft TDC sensor and/or the crank angle position sensor are out of adjustment. |
Push both sensors into their holes as far as they will go. If this does not solve the problem, replace the camshaft TDC sensor and/or crank angle sensor. |
|
The camshaft TDC sensor and/or the crank angle position sensor are damaged. |
Replace the camshaft TDC sensor and/or the crank angle position sensor. |
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There are other problems in the fuel system. |
Check the fuel system. |
|
Problem—The Engine Starts, But Dies |
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|
Cause |
Remedy |
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The fuel tank is low or empty. |
Add fuel and bleed the fuel system, if necessary. |
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The fuel filter is clogged. |
Replace the filter element. |
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The fuel line, the fuel pre-filter, or the screen in the fuel tank is blocked. |
Clean and bleed the system. Check the fuel lines and filters. |
|
The camshaft TDC sensor and/or the crank angle position sensor are out of adjustment. |
Push both sensors into their holes as far as they will go. If this does not solve the problem, replace the camshaft TDC sensor and/or crank angle sensor. |
|
The camshaft TDC sensor and/or the crank angle position sensor are damaged. |
Replace the camshaft TDC sensor and/or crank angle position sensor. |
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The constant-throttle valve(s) are malfunctioning. |
Replace the constant throttle valve(s). |
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There are other problems in the fuel system. |
Check the fuel system. |
|
Problem—The Engine Fan Doesn't Work |
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Cause |
Remedy |
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The fan hub is damaged. |
Replace the fan hub. |
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The fan wiring is damaged. |
Repair the fan wiring. |
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The parameter settings in the DDEC-ECU or DDEC-VCU are incorrect. |
Contact Detroit Diesel Customer Support Center at 313–592–5800. |
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Problem—The Engine Fan Is Constantly On |
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Cause |
Remedy |
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The fan override switch is on. |
Check the operation of the fan override switch. |
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The fan hub is damaged. |
Replace the fan hub. |
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The parameter settings in the DDEC-ECU or DDEC-VCU are incorrect. |
Contact Detroit Diesel Customer Support Center at 313–592–5800. |
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Problem—Fuel Consumption Is Too High |
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Cause |
Remedy |
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The tires are not properly inflated. |
Check all tires for correct pressure. |
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The air filter and/or intake air system is clogged. |
Check the air restriction indicator. Clean the intake air system and replace the air filter if necessary. |
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The fuel filter is clogged. |
Replace the filter element. |
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The exhaust brake valve is malfunctioning. |
Check the operation of the valve. Replace if necessary. |
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The engine performs poorly, or does not develop full power. |
The remedies are listed in Table "The Engine Performs Poorly, Does Not Develop Full Power” in this section. |
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Problem—The Engine Performs Poorly, Does Not Develop Full Power |
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Cause |
Remedy |
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The air filter and/or intake air system is clogged. |
Check the air restriction indicator. Clean the intake air system and replace the air filter if necessary. |
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The exhaust brake valve is malfunctioning. |
Repair or replace exhaust brake valve. |
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The fuel filter is clogged. |
Replace the filter element. |
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There are other problems with the fuel system. |
Check the fuel system. |
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The valves are not adjusted properly. |
Check the valve lash. |
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The coolant temperature sensor is damaged or reading incorrectly. |
Replace the coolant temperature sensor. |
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The fuel temperature sensor is damaged or reading incorrectly. |
Replace the fuel temperature sensor. |
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The engine oil temperature sensor is damaged or reading incorrectly. |
Replace the oil temperature sensor. |
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The charge air temperature sensor is damaged or reading incorrectly. |
Replace the charge air temperature sensor. |
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There are problems with the DDEC-ECU or DDEC-VCU. |
Contact Detroit Diesel Customer Support Center at 313–592–5800. |
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There is internal damage to the engine. |
Repair the internal damage. |
|
Problem—The Engine Is in Emergency Running Mode (constant speed 1300 rpm) |
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Cause |
Remedy |
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The DDEC-ECU or DDEC-VCU is damaged. |
Replace the DDEC-ECU or DDEC-VCU. |
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Problem—The Coolant Temperature Is Above Normal |
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Cause |
Remedy |
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The coolant level is too low. |
Check for coolant leaks, and repair as needed. |
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The poly-vee belt is loose. |
Tighten or replace the poly-vee belt. |
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The coolant temperature gauge and/or sensor is not reading correctly. |
Replace the coolant temperature gauge and/or sensor. |
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The radiator is damaged or dirty. |
Clean the radiator. Repair or replace the radiator if necessary. |
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The coolant pump is damaged. |
Replace coolant pump. |
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The thermostat is damaged. |
Replace the thermostat. |
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The fan is not operating properly. |
Check the fan hub. Contact Detroit Diesel Customer Support Center at 313–592–5800 to have parameter settings reprogrammed in the DDEC-ECU or DDEC-VCU. |
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Problem—The Coolant Temperature Is Below Normal |
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Cause |
Remedy |
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The coolant temperature gauge and/or sensor is not reading correctly. |
Replace the coolant temperature gauge and/or sensor. |
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The thermostat is damaged. |
Replace the thermostat. |
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The fan is not operating properly. |
Check the fan hub. Contact Detroit Diesel Customer Support Center at 313–592–5800 to have parameter settings reprogrammed in the DDEC-ECU or DDEC-VCU. |
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Problem—The Cooling System Is Losing Coolant |
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Cause |
Remedy |
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There is an external coolant leak. |
Repair the leaking component. |
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The radiator cap is leaking. |
Replace the radiator cap. |
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The air compressor head is damaged. |
Replace the air compressor. |
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The cylinder head gasket is leaking. |
Replace the head gasket. |
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Problem—There Is Coolant in the Engine Oil |
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Cause |
Remedy |
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The cylinder head gasket is damaged. |
Replace the head gasket. |
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The oil/water heat exchanger is leaking. |
Replace the heat exchanger. |
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There is an internal coolant leak. |
Check the cooling system for leak and repair. |
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Problem—There Is Foam in the Engine Oil |
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Cause |
Remedy |
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The oil level is too low or too high. |
Correct the oil level. |
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The oil has not been changed within the recommended interval. |
Change the oil. |
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The oil is not of the recommended quality. |
Change the oil. |
|
Problem—The Engine Oil Pressure Is Low |
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Cause |
Remedy |
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The oil pressure gauge and/or sensor is not reading correctly. |
Replace the oil pressure gauge and/or sensor. |
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There is fuel in the oil. |
Check fuel system for leak. |
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The oil filter is clogged. |
Replace the filter element. |
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The oil filter bypass valve is damaged. |
Replace the bypass valve. |
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The oil pump and/or relief valve is damaged. |
Replace the oil pump and/or relief valve. |
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Problem—The Engine Exhaust Is White |
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Cause |
Remedy |
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Fuel quality is not within DDC specifications. |
Take a fuel sample and have it tested. Fuel must have a cetane number greater than 45 and a cetane index greater than 40. Drain fuel and replace with correct fuel. |
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The intake air preheater is malfunctioning. |
Check the intake air preheater, and replace if necessary. |
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The valves are not adjusted properly. |
Check the valve lash. |
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There are air bubbles in the fuel. |
Check for leaks at fuel filter, fuel lines or fuel pump. Repair/replace as necessary. |
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Charge air cooler is damaged. |
Replace damaged charge air cooler. |
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There are air bubbles in the coolant. |
Check for leaking cylinder head gasket. Replace if necessary. |
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Low cylinder compression. |
Damaged cylinder components. Perform cylinder compression test. Repair/replace damaged parts as necessary. |
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Turbocharger boost sensor is damaged or reading incorrectly. |
Replace the turbocharger boost sensor. |
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Faulty DDEC-ECU. |
Check DDEC-ECU; replace if necessary. |
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Defective fuel pump. |
Replace defective fuel pump. |
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Faulty turbocharger control unit. |
Replace turbocharger and control unit. |
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Faulty fuel injector nozzle holder. |
Replace fuel injector nozzle holder. |
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Problem—The Engine Exhaust Is Black |
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Cause |
Remedy |
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The air filter and/or intake air system is clogged. |
Check the air restriction indicator. Clean the intake air system and replace the air filter if necessary. |
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The exhaust brake valve is malfunctioning. |
Replace exhaust brake valve. |
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The intake air preheater is malfunctioning. |
Check that the preheater is not staying on all of the time. Replace preheater if necessary. |
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The valves are not adjusted properly. |
Check the valve lash. |
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There is damage to the fuel system: the fuel pump, fuel nozzle(s), or unit pump(s). |
Check the fuel system. Replace defective fuel pump, fuel nozzle(s), or unit pump(s). |
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The charge air temperature sensor is damaged. |
Replace the charge air temperature sensor. |
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There is internal damage to the engine. |
Repair internal damage in engine. |
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EGR valve not operating properly. |
Replace EGR valve. |
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Turbocharger turbine wheel does not spin freely. |
Replace the turbocharger. |
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Low cylinder compression. |
Damaged cylinder components. Perform cylinder compression test. Repair/replace damaged parts as necessary. |
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There are air bubbles in the fuel. |
Check for leaks at fuel filter, fuel lines or fuel pump. Repair/replace as necessary. |
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The air filter is clogged. |
Clean or replace the air filter. |
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Charge air cooler is damaged. |
Replace damaged charge air cooler. |
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The turbocharger is leaking oil. |
Replace the turbocharger. |
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Fuel quality is not within DDC specifications. |
Take a fuel sample and have it tested. Fuel must have a cetane number greater than 45 and cetane index greater than 40. Drain fuel and replace with correct fuel. |
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Air intake manifold gasket leaking. |
Replace the intake manifold gasket. |
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Faulty exhaust manifold gaskets. |
Replace faulty exhaust manifold gaskets. |
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Misadjusted exhaust brake valve. |
Adjust exhaust brake valve. |
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Faulty exhaust brake valve. |
Replace exhaust brake valve. |
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Faulty constant throttle valve. |
Replace constant throttle valve. |
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Problem—The Engine Exhaust Is Blue |
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Cause |
Remedy |
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The engine oil level is too high (engine oil is reaching the combustion chamber). |
Adjust the oil level, and then recheck oil level. |
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The turbocharger is leaking oil. |
Replace the turbocharger. |
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The valve stem seals are loose or damaged. |
Replace the valve stem seals. |
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The piston rings are worn. |
Replace the piston rings. |
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Low cylinder compression. |
Damaged cylinder components. Perform cylinder compression test. Repair/replace damaged parts as necessary. |
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The oil is not of the recommended quality. |
Change the oil. |
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Problem—Engine Brake Performance Is Poor |
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|
Cause |
Remedy |
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The engine brake control switch is damaged. |
Replace the brake control switch. |
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The exhaust brake is not operating properly. |
Check the operation of the valve. Replace valve if necessary. |
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The constant-throttle valves are malfunctioning. |
Replace the malfunctioning constant-throttle valve(s). |
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Components of the DDEC-ECU and/or DDEC-VCU are damaged. |
Replace the damaged DDEC-ECU and/or DDEC-VCU. |
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Problem—Cruise Control Is Not Working |
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Cause |
Remedy |
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One or more of the cruise control switches are damaged. |
Replace the damaged switch(es). |
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Components of the DDEC-ECU and/or DDEC-VCU are damaged or not working properly. |
Replace the damaged DDEC-ECU and/or DDEC-VCU. |
|
Problem — The Fuel Pressure is Too High Downstream of the Fuel Filter |
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Possible Cause |
Remedy |
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The continuous ventilation port in the cap of the main fuel filter is blocked. |
Inspect the continuous ventilation port for blockage. Clean the port and replace the cap if necessary. |
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The fuel drain lines downstream of the main filter housing are kinked or blocked. |
Repair/Replace as necessary. |
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The check valve in the fuel feed line is blocked or not open wide (the flange at the fitting connection is bent.) |
Repair/Replace as necessary. |
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The fuel return line and/or strainer at the fuel level sensor is blocked or kinked. |
Remove the fuel level sensor and repair or replace the line or strainer, as necessary. |
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The overflow valve is faulty, or the incorrect valve has been installed. The valve jams when closed as a result of wear or impurities in the fuel. |
Inspect the overflow valve. Replace as necessary. NOTE: Do not attempt to disassemble the overflow valve. The overflow valve cannot be repaired. |
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Problem — Fuel Flows Out of the Fuel Return Line |
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Possible Cause |
Remedy |
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At one or more of the nozzle holders, the transfer tube is leaking, cracked, or incorrectly installed. |
Replace the damaged transfer tube(s), or install it correctly. |
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One or more nozzle holders are leaking, cracked, or incorrectly installed. |
Remove and inspect the nozzle holder(s). Replace if necessary. |
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On one or more nozzle holders, the O-ring between the nozzle holder and the heat isolator is leaking. |
Remove the nozzle holder(s) and replace the O-ring(s). |
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On one or more nozzle holders, the O-ring between the nozzle holder and the cylinder head is leaking. |
Inspect the engine oil at the dipstick for the presence of fuel. Inspect all the nozzle holders, and especially their O-rings, for leaks. Remove the nozzle holder(s) and replace the O-rings, if necessary. Replace the nozzle holder(s) if cracked or otherwise broken, and install correctly. |
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At one or more nozzle holders, the heat isolator is cracked, faulty, or not sealing properly. |
Remove and inspect the heat isolator(s). Replace if necessary. |
|
The cylinder head is cracked or there is cavitation in the oil chamber. |
Inspect the engine oil at the dipstick for the presence of fuel. Replace the cylinder head if necessary. |
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Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Too High at the Filter |
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Possible Cause |
Remedy |
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The main fuel filter is leaking. |
Repair or replace the leaking main fuel filter. |
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The O-ring in the main fuel filter is worn, missing, or incorrectly installed. |
Replace the O-ring, or install it correctly. |
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The main fuel filter cap is loose. |
Tighten the to cap 25 N·m (18 lb·ft). |
|
At one or more of the nozzle holders, the transfer tube is leaking, cracked, or incorrectly installed. |
Replace the transfer tube(s), or install it correctly. |
|
One or more nozzle holders are leaking, or cracked. |
Replace the nozzle holder(s). |
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Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Within Range at the Filter |
|
|
Possible Cause |
Remedy |
|
The filter element in the fuel pre-filter is blocked. |
Replace the filter element. |
|
The filter element in the main fuel filter is blocked or contaminated. |
Clean the inside of the main fuel filter housing. Replace the filter element. |
|
The fuel feed lines are kinked or blocked. |
Inspect the lines, fittings, and check valve for blockage. Repair any kinks and replace the lines. |
|
The suction pipe or the strainer at the fuel level is blocked, or touching the bottom of the fuel tank. |
Open the fuel fill cap. Inspect the suction pipe and strainer. Remove any blockages, and reposition the suction pipe, if necessary. Remove the fuel level sensor and replace it if necessary. |
|
The check valve in the fuel feed line is blocked or is not sufficiently open (the opening flange is bent at the fitting). |
Repair/replace as necessary. |
|
The overflow valve is faulty, or the incorrect valve has been installed. The valve jams when closed as a result of wear or impurities in the fuel. |
Inspect the overflow valve. Replace as necessary. NOTE: Do not attempt to disassemble the overflow valve. The overflow valve cannot be repaired. |
|
Problem — The Fuel Inlet Pressure is Too Low |
|
|
Possible Cause |
Remedy |
|
The pre-filter is leaking (drawing air). |
Replace the O-ring. Replace the filter element and tighten the cap on the filter housing 25 N·m (18 lb·ft). |
|
The fuel feed lines and connections are leaking (drawing air). |
Replace the seals on the leaking lines. Tighten the fittings on the fuel lines to 25 N·m (18 lb·ft) and perform a fuel leak test. |
|
The fuel pump is worn. |
Replace the fuel pump. |
|
The pressure limiting valve in the fuel pump is jammed open or the drive lever is loose or broken. |
Replace the fuel pump. |
|
The air-admission valve in the fuel tank is blocked. |
Remove air-admission valve blockage. |
|
The suction line and/or strainer at the fuel level sensor is blocked or is touching the bottom of the fuel tank. |
Inspect the suction line and/or strainer through the fuel fill opening in the fuel tank. Remove the fuel level sensor and repair or replace the line or strainer, as necessary. |
|
Problem — The Fuel Inlet Pressure is Too High |
|
|
Possible Cause |
Remedy |
|
The fuel feed lines are kinked or blocked. |
Inspect the lines and fittings for blockage. Repair/replace as necessary. |
|
The suction line and/or strainer at the fuel level sensor is blocked or is touching the bottom of the fuel tank. |
Inspect the suction line and/or strainer through the fuel fill opening in the fuel tank. Remove the fuel level sensor and repair or replace the line or strainer, as necessary. |
|
The check valve in the fuel feed line is blocked or not open wide (the flange at the fitting connection is bent). |
Repair/replace as necessary. |
|
Problem — The Low-Pressure Fuel System is Leaking |
|
|
Possible Cause |
Remedy |
|
The engine is leaking at external connections such as the fuel temperature sensor, the fittings at the base of the fuel filter housing, and/or the overflow valve. |
Replace seals and/or gaskets as necessary. Tighten all high-pressure lines to 25 N·m (18 lb·ft) and all banjo bolts to 40 - 50 N·m (30 - 37 lb·ft). |
|
The O-ring at one or more unit pumps is leaking, worn, or missing. |
Inspect the engine oil at the dipstick for the presence of fuel. Inspect the injector line fittings at the fuel pumps for leaks. Remove the unit pump(s) and replace the O-rings, if necessary. |
|
The O-ring at one or more nozzle holders is leaking, or the nozzle holders themselves are cracked or incorrectly installed. |
Inspect the engine oil at the dipstick for the presence of fuel. Inspect all the nozzle holders, and especially their O-rings, for leaks. Remove the nozzle holder(s) and replace the O-rings, if necessary. Replace the nozzle holder(s) if cracked or otherwise broken, and install correctly. |
|
The cylinder head is cracked or there is cavitation in the oil chamber. |
Inspect the engine oil at the dipstick for the presence of fuel. Replace the cylinder head if necessary. |
|
There are balls of sealant in the fuel feed line, or the return port is leaking at the cylinder block. |
Replace the cylinder block seals. |
| MBE 900 Service Manual - 6SE414 |
| Generated on 10-13-2008 |