Yuchai 4D24/4D24T Engine Exhaust White and Blue Smoke

Fuel quality does not meet the requirements:

1. Use incorrect grade of fuel;

2. Excessive fuel impurities;

3. Excessive water in fuel.

Replace by quality fuel, and clean fuel circuit.

Fault code in ECU memory:

1. Fault codes can be read through the diagnostic apparatus;

2. Fault flash codes can be read through diagnostic request switch;

3. Electronic control system fault information can be read through CAN meter.

1. If the fault code or fault flash code information clearly points to a specific electronic control components, inspect and repair the corresponding faults of sensors, actuators and its line;

2. If read fuel volume slip ring control model related fault codes or fault flash

codes information, focus on investigation fuel related failures according to the subsequent steps;

3. After repairs, use the diagnostic apparatus or diagnostic request switch to delete the fault history information, and fully running engine to confirm ECU memory without fault code information.

Cooling water temperature sensor or circuit fault

Check the cooling water temperature sensor and its circuit, through the diagnostic instrument monitoring the temperature signal value to see if lower than the actual value; dismantle the coolant temperature sensor connector if necessary, and start engine to compare

The resistance of air intake system exceeds technical requirement

Check if the intake system is blocked. If necessary, clean or replace the air filter and the intake manifold.

Intake or exhaust leakage

Check whether the air intake system and the exhaust system leak air.

Blockage or leakage of radiator

Check if the radiator is blocked or leaked.

Exhaust system resistance exceeds technical requirement

Check if the exhaust system is blocked.

Muffler extrusion deformation or blockage

Replace muffler

Injector fault

1. Check injector atomizing;

2. Check injector shim thickness correct or not;

3. Check injector protrusion height correct or not.

Valve leakage or valve clearance abnormal

Check and adjust the valve seal and valve clearance

Insufficient pressure of the turbo system

Check and solve the leakage from the pipe and connection.

Turbocharger operation disorder

The turbocharger cannot be rotated or stuck, check and replace turbocharger

Power consumption is too large

Check whether the working cycle time of the cooling fan and the driving device of the diesel engine are working normally.

Internal damage of diesel engine

Check and replace damaged parts at the service station.

Fuel quality does not meet the requirements:

1. Use incorrect grade of fuel;

2. Excessive fuel impurities;

3. Excessive water in fuel;

Replace by qualified fuel, and clean fuel circuit.

Cooling water temperature sensor or circuit fault

Check the cooling water temperature sensor and its circuit, through the diagnostic instrument monitoring the temperature signal value to see if lower than the actual value; dismantle the coolant temperature sensor connector if necessary,and start engine to compare

Diesel engines work at lower temperatures

Check the working temperature of the thermostat and replace it if necessary.

The temperature is too low to start the auxiliary preheat failure

Check whether the preheating plug is able to work properly.

Low pressure fuel circuit failure

1. Make sure there is enough diesel in

the tank;

2. Elimination of air in low pressure fuel circuit;

3. Check the pipes, the joint tightening condition, and, whether the hose and the joint are affected by extrusion, damage, or the diameter is not correct;

4. Check whether the fuel filter, pre-filter are blocked or damaged;

5. Check whether the fuel tank ventilation device is blocked or contaminated (open tank cover and check pumping sound);

6. Check whether the fuel pump and the inlet & outlet of filter are connected incorrectly;

7. Check whether transfer pump is failure.

Air filter clogging resulted in an increase in the cylinder intake resistance and poor intake, forming a certain negative pressure, the lubricating oil is absorbed into the combustion chamber.

Check whether the air filter is blocked.

Oil level of oil pan is too high

Check whether the oil level of oil pan exceeds the upper limit or not.

Turbocharger seal ring worn

Check and replace

Turbocharger thrust bearing worn

Check and replace

Turbocharger oil return line block

Clean, repair

Injector fault

1. Check injector atomizing;

2. Check injector shim thickness correct or not;

3. Check injector protrusion height correct or not.

Valve leakage or abnormal lash

Check and adjust the valve seal and valve clearance.

Coolant leaking into the combustion chamber

Check the coolant leaks

Cylinder wall, piston and piston ring wear serious, too large clearance, cause oil sneaked into the combustion chamber and burn

Check condition of cylinder wall, piston and piston ring

Clearance between valve and guide is too large, oil is sucked into the combustion chamber

Replace worn valve and valve guide

Compression pressure is low, the combustion is not complete

Check the piston ring and cylinder gasket

Piston ring installation in the wrong direction, openings have not staggered

Check and re-assembly.

Long-term low-load operation

Pay attention to use appropriate operating speed and load.

Internal damage of diesel engine

Analysis of the oil and check the oil filter, identify possible damaged parts.

Oil temperature gauge, oil pressure sensor or oil temperature sensor failure, or installed wrong location

Check whether the oil pressure gauge, oil pressure sensor, oil temperature sensor or their circuits work properly, and whether they are in the correct position.

Lubricating oil thinning or improper use of lubricating oil

Select appropriate lubricating oil according to provisions

Oil filter regulator failure or improper adjustment

Repair

Oil filter clogging

Replace oil filter

Lubricating oil pump inlet pipe crack

Repair or replace

Fixing bolts of inlet pipe of lubricating oil pump loose

Tighten to the specified torque

Rotor of lubricating oil pump wear or too large assembly clearance

Replace the oil pump

Bearing clearance is too large

Check and replace

Oil temperature gauge, oil pressure  sensor or oil temperature sensor failure, or installed wrong location

Check whether the oil pressure gauge, oil pressure sensor, oil temperature sensor or their circuits work properly, and whether they are in the correct position.

Temperature is too low, oil viscosity increases

Select specified grade lubricating oil, low speed running after start, inspectionafter oil temperature become normal.

Relief valve blocked

Inspect and clean

External lubricating oil pipeline leaks

Check and repair

Diesel engine overload

1. Reducing the load

2. Confirm whether the intake system abnormality, diesel engine will cause   overload if blocked.

Improper use of lubricating oil

Choose according to regulations.

Dipstick calibrates incorrectly

Check or replace dipstick

Breather blocked

Replace breather

Air filter blocked, oil sneak into turbocharger

Check whether the air filter is blocked, confirm the turbocharger shaft rotation is normal rotation without clamping.

Piston ring jammed or wear too much

Check, repair and replace if necessary

Cylinder hole worn too much

Holing and replace piston ring

Valve guide wear too much, valve stem seal failure

Check and replace

Lack of cooling water, the water flow is inappropriate small

Check whether the cooling water is adequate, add if insufficient

Whether the belt is too loose

Adjust

The water temperature instrument damage, the water temperature induction plug failure

Check whether the actual temperature is consistent with the temperature indicator; if not, replace the induction plug or water temperature instrument.

Expansion tank does not seal well

Repair in time

Water pump leaks

Repair in time

Thermostat failure, damage

Check and replace

Punching cylinder gasket

Check and replace

Matching problem between radiator and fan under modification condition

Re-match on request