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Diesel Engine Fault Diagnosis Methods

Date: 2023-06-15 View:

 Diesel Engine Troubleshooting Methods

1:The low-pressure oil circuit is not well supplied

The inlet and return pipelines between the diesel engine from the fuel tank
to the inlet cavity of the fuel injection pump are low-pressure oil circuits,
when the pipeline joints, gaskets and oil pipes leakage due to damage,
it will cause air into the oil circuit to produce air resistance,
resulting in poor fuel supply, difficult engine start, slow acceleration and other failures,
and will automatically  turn off when it is serious. When the oil pipe is aging,
deformation and impurity blockage reduce the cross-sectional area of the oil,
or the oil is dirty and plugged to talk about the oil filter screen and diesel filter,
it will cause insufficient fuel supply. And make the engine power drop and start difficult.
When checking the fault, use the hand oil pump to pump the oil to a certain pressure,
loosen the air screw, if there is a bubble overflow and the exhaust is not exhausted,
it means that the oil path enters the air. If there are no air bubbles,
but the diesel fuel overflows weakly from the outside of the bleed screw,
the oil circuit is blocked.
The way to troubleshoot is to find out the damaged or aging gaskets,
joints or tubing and replace them. To prevent such failures,
clean the oil inlet filter and diesel filter element frequently,
check the pipeline frequently, and solve the problem in time.

2: The piston spring of the oil transfer pump is broken

 The engine suddenly stalled during operation, could not start, restarted after exhaust clean air,
resumed normal driving for a distance, and automatically turned off again,
most likely the fuel pump piston bullet broke.
The troubleshooting method is to unscrew the screw and replace the spring to eliminate it.

3: The check valve of the oil transfer pump is not tightly sealed

It is difficult to start after the engine is turned off and stopped for a ceratin period of time,
and the air is overflowed when the deflated screw is loosened,
and the air needs to be re-drained to start.
This failure is mostly caused by the poor sealing of the check valve of the oil pump.
The inspection method is to unscrew the oil outlet screw of the oil transfer pump,
and use the hand oil pump to fill the oil outlet joint oil cavity,
if the oil level in the joint drops quickly within 3 minutes,
it means that the one-way seal is not good.
Remove the check valve to check whether the sealing surface
is intact and whether the check valve spring is broken or deformation,
whether there are particulate impurities attached to the sealing seat surface,
respectively take the grinding sealing surface,
replace the one-way shallow or one-way feeling spring will troubleshoot.

 4: The high-pressure oil pipe is blocked

When a cylinder high-pressure oil pipe is blocked due to deformation or impurities,
there is an obvious knocking sound in the oil pipe after starting the engine,
and the engine power drops because the cylinder cannot work normally .
The inspection method is to loosen the oil inlet end nut of the high-pressure
oil pipe cylinder by cylinder, when the knocking sound disappears after unscrewing a certain cylinder,
it can be concluded that the cylinder is a faulty cylinder,
and the fault can be eliminated after replacing the oil pipe.