Lubrication system fault diagnosis analysis
a. Excessive oil consumption
First of all, it is necessary to determine whether there is external oil leakage in the diesel engine; (start the diesel engine and run it until the outlet water temperature reaches 80 degrees, and check whether the gaskets, seals, "O" ring seals, bulkheads, pipe joints, rubber pipes, etc. outside the diesel engine are leaking. .)
Secondly, check whether the diesel engine crankcase ventilation system is blocked;
If the piston ring seal is poor, the oil will enter the combustion chamber and be burned or the air leakage will be too large, and the oil droplets will be blown out of the body through the crankcase ventilation mechanism along with the leaked combustion gas.
b. Inspect the internal damage of the diesel engine, cut open the oil filter, and check the following items:
Metal: Possible cause of particle failure
The copper bearing bush or connecting rod small end bushing is damaged
Chrome piston ring wear
The lead bearing coating material is severely worn
Aluminum piston worn or damaged
c. Lubrication system fault diagnosis
To diagnose lubrication system failures, it is necessary to check various parts related to the engine oil, such as oil pressure gauge, engine oil fluid, oil contamination, oil viscosity, etc.
d. Oil pressure is too high
In cold weather, the oil pressure is usually too high after the diesel engine is started for the first time. It is also possible that the oil pressure regulating valve is stuck at the high pressure position, the oil level is too high, the oil viscosity is too high, etc.
e. Oil pressure is too low
Many lubrication system failures can reduce oil pressure. When the oil pressure is found to be too low, you should first determine whether the operating conditions of the diesel engine are normal, and then check for faults.
Possible causes: low oil level, clogged oil filter, damaged oil pressure gauge (check whether the wire is broken, whether the pressure sensor component is failed, whether the pipeline is leaking or broken), excessive wear of the oil pump (this fault is usually caused by It will only occur when the diesel engine has been running for a long time), and the engine oil becomes thinner (if the engine oil becomes thinner and black, it means that it is mixed with fuel; if the engine oil is milky and white, it means that it is mixed with coolant).
Parts that may cause problems when engine oil is mixed with coolant:
(1), oil cooler
Possible parts: cracked cooler, loose oil inlet and outlet flange, damaged gasket, cracked cooler core, etc.
Inspection method: When the diesel engine is running, the oil pressure is higher than the coolant pressure. If any of the above problems occurs in the oil cooler, the oil will be mixed into the coolant. Open the radiator cap and you will see oil in the coolant, and the coolant will overflow from the radiator.
(2), intercooler
Analysis: If the intercooler leaks, the coolant will leak into the intake pipe and then flow into the cylinder and leak into the oil pan through the piston ring channel.
Inspection method: Remove the intercooler and check whether there is any sign of coolant leaking into the intake pipe.
(3) Aging and damage of the cylinder head sealing ring, damage to the cylinder head gasket, cracks in the cylinder head, cracks in the water chamber of the cylinder head, and cracks in the body (for these problems, you can remove the oil pan and check the cooling system pump pressure at 140Kpa examine)
Diesel leaks into the oil: Diesel leaks from the piston rings into the oil pan (combustion in the cylinder is incomplete, and unburned fuel will leak into the oil pan. The above situation is due to the failure of the piston ring seal, resulting in a reduction in the compression ratio or dripping from the injector. (caused by oil); the increase in exhaust white smoke when starting for the first time every day is a sign of oil leakage from the fuel injector. Oil leakage from the fuel injector will also cause the diesel engine to run rough and reduce power.
