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MBE 900 GENERAL TROUBLESHOOTING

The tables that follow are designed to identify the causes of common problems, suggest further checks and appropriate remedies. When dealer service is necessary, it is addressed in the table. ‪

Problem - The Engine Will Not Crank ‪

Cause ‪

Remedy ‪

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. ‪

Have an authorized dealer replace the starter. ‪

The clutch or transmission is damaged. ‪

Bring the vehicle to an authorized dealer for service. ‪

There is internal damage to the engine. ‪

Bring the vehicle to an authorized dealer for service. ‪

Problem The Engine will Not Crank

ProblemThe Engine Turns Over Slowly ‪

Cause ‪

Remedy ‪

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. ‪

Have an authorized dealer replace the starter. ‪

The engine oil does not meet the correct specifications. ‪

Change the engine oil, using the correct type of oil. ‪

The transmission fluid does not meet the correct specifications. ‪

Change the transmission fluid, using the correct type of fluid. ‪

Problem The Engine Turns Over Slowly

ProblemThe Engine Cranks, But Won't Start ‪

Cause ‪

Remedy ‪

The batteries are damaged or weak. ‪

Test the batteries. Replace them, if needed. ‪

The cranking speed is not set correctly. ‪

Bring the vehicle to an authorized dealer for service. ‪

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, bring the vehicle to an authorized dealer for service. ‪

The camshaft TDC sensor and/or the crank angle position sensor are damaged. ‪

Bring the vehicle to an authorized dealer for service. ‪

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. ‪

The air filter is clogged. ‪

Clean or replace the air filter. ‪

The fuel filter is clogged. ‪

Replace the filter element. ‪

The exhaust brake valve is malfunctioning. ‪

Have an authorized dealer check the operation of the valve. ‪

The valves are not adjusted properly. ‪

Check the valve lash. ‪

There are other problems in the fuel system. ‪

Bring the vehicle to an authorized dealer for service. ‪

Problem The Engine Cranks, But Won't Start

ProblemThe Engine Starts Only After Cranking for a Long Time ‪

Cause ‪

Remedy ‪

The fuel tank is low or empty. ‪

Add fuel and bleed the fuel system, if necessary. ‪

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. Have the fuel lines and filters checked by an authorized dealer. ‪

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, bring the vehicle to an authorized dealer for service. ‪

The camshaft TDC sensor and/or the crank angle position sensor are damaged. ‪

Bring the vehicle to an authorized dealer for service. ‪

There are other problems in the fuel system. ‪

Bring the vehicle to an authorized dealer for service. ‪

Problem The Engine Starts Only After Cranking for a Long Time

ProblemThe Engine Starts, But Dies ‪

Cause ‪

Remedy ‪

The fuel tank is low or empty. ‪

Add fuel and bleed the fuel system, 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. Have the fuel lines and filters checked by an authorized dealer. ‪

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, bring the vehicle to an authorized dealer for service. ‪

The camshaft TDC sensor and/or the crank angle position sensor are damaged. ‪

Bring the vehicle to an authorized dealer for service. ‪

The constant-throttle valves are malfunctioning. ‪

Bring the vehicle to an authorized dealer for service. ‪

There are other problems in the fuel system. ‪

Bring the vehicle to an authorized dealer for service. ‪

Problem The Engine Starts, But Dies

ProblemThe Engine Fan Doesn't Work ‪

Cause ‪

Remedy ‪

The fan hub is damaged. ‪

Replace the fan hub. ‪

The fan wiring is damaged. ‪

Repair the fan wiring. ‪

The parameter settings in the DDEC-ECU or DDEC-VCU control unit are incorrect. ‪

Have an authorized dealer reprogram the control unit. ‪

Problem The Engine Fan Doesn't Work

ProblemThe Engine Fan Is Constantly On ‪

Cause ‪

Remedy ‪

The fan override switch is on. ‪

Check the operation of the fan override switch. ‪

The fan hub is damaged. ‪

Replace the fan hub ‪

The parameter settings in the DDEC-ECU or DDEC-VCU control unit are incorrect. ‪

Have an authorized dealer reprogram the control unit. ‪

Problem The Engine Fan is Constantly On

ProblemFuel Consumption Is Too High ‪

Cause ‪

Remedy ‪

The tires are not properly inflated. ‪

Check all tires for correct pressure. ‪

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. ‪

The fuel filter is clogged. ‪

Replace the filter element. ‪

The exhaust brake valve is malfunctioning. ‪

Have an authorized dealer check the operation of the valve. ‪

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. ‪

Problem Fuel Consumption is Too High

ProblemThe Engine Performs Poorly, Does Not Develop Full Power ‪

Cause ‪

Remedy ‪

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. ‪

The exhaust brake valve is malfunctioning. ‪

Have an authorized dealer check the operation of the valve. ‪

The fuel filter is clogged. ‪

Replace the filter element. ‪

There are other problems with the fuel system. ‪

Bring the vehicle to an authorized dealer for service. ‪

The valves are not adjusted properly ‪

Check the valve lash. ‪

The coolant temperature sensor is damaged or reading incorrectly. ‪

Bring the vehicle to an authorized dealer for service. ‪

The fuel temperature sensor is damaged or reading incorrectly. ‪

Bring the vehicle to an authorized dealer for service. ‪

The engine oil temperature sensor is damaged or reading incorrectly. ‪

Bring the vehicle to an authorized dealer for service. ‪

The charge-air temperature sensor is damaged or reading incorrectly. ‪

Bring the vehicle to an authorized dealer for service. ‪

There are problems with the DDEC-ECU or DDEC-VCU control unit. ‪

Bring the vehicle to an authorized dealer for service. ‪

There is internal damage to the engine. ‪

Bring the vehicle to an authorized dealer for service. ‪

Problem The Engine Performs Poorly, Does Not Develop Full Power

ProblemThe Engine Is in Emergency Running Mode (constant speed 1,300 rpm) ‪

Cause ‪

Remedy ‪

The DDEC-ECU or DDEC-VCU control unit is damaged. ‪

Bring the vehicle to an authorized dealer for service. ‪

Problem The Engine is in Emergency Running Mode (constant speed 1,300 rpm)

ProblemThe Coolant Temperature Is Above Normal ‪

Cause ‪

Remedy ‪

The coolant level is too low. ‪

Check for coolant leaks, and repair as needed. ‪

The poly-V belt is loose. ‪

Tighten or replace the poly-V belt. ‪

The coolant temperature gauge and/or sensor is not reading correctly. ‪

Bring the vehicle to an authorized dealer for service. ‪

The radiator is damaged or dirty. ‪

Clean the radiator. Repair or replace the radiator if necessary. ‪

The coolant pump is damaged. ‪

Have an authorized dealer replace the coolant pump. ‪

The thermostat is damaged. ‪

Have an authorized dealer replace the coolant pump. ‪

The fan is not operating properly. ‪

Bring the vehicle to an authorized dealer and have the fan hub checked. ‪

Bring the vehicle to an authorized dealer and have the parameter settings reprogrammed in the engine control unit (DDEC-ECU) or vehicle control unit (DDEC-VCU). ‪

Problem The Coolant Temperature is Above Normal

ProblemThe Cooling System Is Losing Coolant ‪

Cause ‪

Remedy ‪

There is an external coolant leak. ‪

Repair the leaking component. ‪

The radiator cap is leaking. ‪

Replace the radiator cap. ‪

The air compressor head is damaged. ‪

Have an authorized dealer replace the air compressor. ‪

The cylinder head gasket is leaking. ‪

Have an authorized dealer replace the head gasket. ‪

Problem The Cooling System is Losing Coolant

ProblemThere Is Coolant in the Engine Oil ‪

Cause ‪

Remedy ‪

The cylinder head gasket is damaged. ‪

Have an authorized dealer replace the head gasket. ‪

The oil/water heat exchanger is leaking. ‪

Have an authorized dealer replace the heat exchanger. ‪

There is an internal coolant leak. ‪

Bring the vehicle to an authorized dealer for service. ‪

Problem There is Coolant in the Engine Oil

ProblemThere Is Foam in the Engine Oil ‪

Cause ‪

Remedy ‪

The oil level is too low or too high. ‪

Correct the oil level. ‪

The oil has not been changed within the recommended interval. ‪

Change the oil. ‪

The oil is not of the recommended quality. ‪

Change the oil. ‪

Problem There is Foam in the Engine Oil

ProblemThe Engine Oil Pressure Is Low ‪

Cause ‪

Remedy ‪

The oil pressure gauge and/or sensor is not reading correctly. ‪

Bring the vehicle to an authorized dealer for service. ‪

There is fuel in the oil. ‪

Bring the vehicle to an authorized dealer for service. ‪

The oil filter is clogged. ‪

Replace the filter element. ‪

The oil filter bypass valve is damaged. ‪

Replace the bypass valve. ‪

The oil pump and/or relief valve is damaged. ‪

Have an authorized dealer replace the oil pump. ‪

Problem The Engine Oil Pressure is Low

ProblemThe Engine Exhaust Is White ‪

Cause ‪

Remedy ‪

The fuel is of poor quality. ‪

Add fuel of the right quality. ‪

The intake air preheater is malfunctioning. ‪

Check the intake air preheater, and replace it, if necessary. ‪

The valves are not adjusted properly. ‪

Check the valve lash. ‪

Problem The Engine Exhaust is White

ProblemThe Engine Exhaust Is Black ‪

Cause ‪

Remedy ‪

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. ‪

The exhaust brake valve is malfunctioning. ‪

Have an authorized dealer check the operation of the valve. ‪

The intake air preheater is malfunctioning. ‪

Check that the heater is not staying on all of the time. ‪

The valves are not adjusted properly. ‪

Check the valve lash. ‪

There is damage to the fuel system: the fuel pump, one or more fuel injectors, or one or more unit pumps are damaged. ‪

Bring the vehicle to an authorized dealer for service. ‪

The charge-air temperature sensor is damaged. ‪

Bring the vehicle to an authorized dealer for service. ‪

There is internal damage to the engine. ‪

Bring the vehicle to an authorized dealer for service. ‪

Problem The Engine Exhaust is Black

ProblemThe Engine Exhaust Is Blue ‪

Cause ‪

Remedy ‪

The engine oil level is too high (engine oil is reaching the combustion chamber). ‪

Adjust the oil level, and then have the oil level checked by an authorized dealer. ‪

The turbocharger is leaking oil. ‪

Have an authorized dealer replace the turbocharger ‪

The valve stem seals are loose or damaged. ‪

Have an authorized dealer replace the seals. ‪

The piston rings are worn. ‪

Have an authorized dealer replace the piston rings. ‪

Problem The Engine Exhaust is Blue

ProblemEngine Brake Performance Is Poor ‪

Cause ‪

Remedy ‪

The engine brake control switch is damaged. ‪

Replace the switch ‪

The exhaust brake is not operating properly. ‪

Have an authorized dealer check the operation of the valve. ‪

The constant-throttle valves are malfunctioning. ‪

Bring the vehicle to an authorized dealer for service. ‪

Components of the DDEC-ECU and/or DDEC-VCU control unit are damaged. ‪

Bring the vehicle to an authorized dealer for service. ‪

Problem Engine Brake Performance is Poor

ProblemCruise Control Is Not Working ‪

Cause ‪

Remedy ‪

One or more of the cruise control switches are damaged. ‪

Replace the damaged switch. ‪

Components of the DDEC-ECU and/or DDEC-VCU control unit are damaged or not working properly. ‪

Bring the vehicle to an authorized dealer for service. ‪

Problem Cruise Control is Not Working

ProblemThe Battery Charge Indicator Light Does Not Come On When the Engine Is Not Running ‪

Cause ‪

Remedy ‪

The bulb is damaged. ‪

Change the bulb. ‪

The circuit is broken. ‪

Repair the break in the circuit. ‪

Problem The Battery Charge Indicator Light Does Not Come on When the Engine is Not Running

ProblemThe Battery Charge Indicator Light Comes On When the Engine is Running ‪

Cause ‪

Remedy ‪

The poly-V belt is too loose. ‪

Check the belt tension; if necessary, have an authorized dealer replace the belt tensioner. ‪

The belt tensioner is damaged. ‪

Have an authorized dealer replace the belt tensioner. ‪

The poly-V belt is worn or damaged. ‪

Replace the belt. ‪

The alternator is damaged (has a damaged rectifier or voltage regulator). ‪

Have an authorized dealer replace the alternator. ‪

Problem The Battery Charge Indicator Light Comes on When the Engine is Running

Problem The Fuel Pressure is Too High Downstream of the Fuel Filter ‪

Possible Cause ‪

Remedy ‪

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. ‪

The fuel drain lines downstream of the main filter housing are kinked or blocked. ‪

Repair/Replace 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. ‪

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. ‪

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. Repair/replace as necessary. ‪

NOTE: Do not attempt to disassemble the overflow valve. The overflow valve cannot be repaired. ‪

Problem Fuel Pressure is Too High Downstream of the Fuel Filter

Problem Fuel Flows Out of the Fuel Return Line ‪

Possible Cause ‪

Remedy ‪

At one or more of the nozzle holders, the transfer tube is leaking, cracked, or incorrectly installed. ‪

Replace the transfer tube, or install it correctly. ‪

One or more nozzle holders are leaking, cracked, or incorrectly installed. ‪

Remove and inspect the nozzle holder(s). Replace if necessary. ‪

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). ‪

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. ‪

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. ‪

Problem Fuel Flows Out of the Fuel Return Line

Problem Fuel Flow Quantity is Too Low at the Overflow Valve and Too High at the Filter ‪

Possible Cause ‪

Remedy ‪

The filter element in the main fuel filter is leaking. ‪

Replace the filter element. ‪

The O-ring in the main fuel filter is worn, missing, or incorrectly installed. ‪

Replace the O-ring, or install it correctly. ‪

The main fuel filter cap is loose. ‪

Tighten the cap 25 Nm (18 lbft). ‪

At one or more of the nozzle holders, the transfer tube is leaking, cracked, or incorrectly installed. ‪

Replace the transfer tube, or install it correctly. ‪

One or more nozzle holders are leaking, or cracked. ‪

Replace the nozzle holder(s). ‪

Problem Fuel Flow Quantity is Too Low at the Overflow Valve and Too High at the Filter

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. Repair/replace as necessary. ‪

NOTE: Do not attempt to disassemble the overflow valve. The overflow valve cannot be repaired. ‪

Problem Fuel Flow Quantity is Too Low at the Overflow Valve and Within Range at the Filter

Problem The 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 Nm (18 lbft). ‪

The fuel feed lines and connections are leaking (drawing air). ‪

Replace the seals on the leaking lines. Tighten the fittings on the fuel lines 25 Nm (18 lbft) and do the 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 Inlet Pressure is Too Low

Problem The 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 Inlet Pressure is Too High

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 25 Nm (18 lbft) and all banjo bolts 40 Nm (30 lbft). ‪

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. ‪

Problem The Low-Pressure Fuel System is Leaking