How to Identify Engine Failure?

Jun. 29, 2020

Many times when the engine is "discomfortable", if the engine problem is not discovered and dealt with in time, some of the original problems will be magnified to replace the entire component, which is undoubtedly a waste of time and money. Today, a custom distributor is here to help Card Friends quickly identify engine failures and avoid spending money!

First listen: the camshaft rings

Phenomenon: When the engine is at medium speed, heavy noise is emitted from the side of the cylinder block Chery camshaft; the noise is chaotic at high speed. When the oil is cut off in a single cylinder, the sound does not change. There is vibration near the camshaft bearing.

Cause: The clearance between the camshaft bearing and the journal is too large and loose. The camshaft bearing is loose or the bearing alloy is ablated, peeled, or worn too much, the axial clearance of the camshaft is too large or the camshaft is bent.

Diagnosis and elimination: Make the engine auscultate on the cylinder with the stethoscope at the loudest rotation speed. If the sound is strong and accompanied by vibration, the bearing can be diagnosed. If the sound of idle speed is clear, the sound of medium speed is obvious, and the sound of high speed becomes weaker from the disorder, it can be diagnosed that the axial clearance of the camshaft is too large or the bearing is loose.

Chery Camshaft

Chery Camshaft

Second listen: valve leak

Phenomenon: When a fault occurs, the engine will have difficulty starting, the exhaust pipe will fire, smoke, fuel consumption will increase, and abnormal noise will occur.

Reasons: Valve and valve seat working surface are abraded, ablated, poorly sealed, and the valve and valve seat working surface have carbon deposits, the valve is not closed tightly and leaks; the gap between the valve and the valve guide is too large, and the valve rod is swayed, which leads to The intake valve is not tightly closed and leaks. The valve stem is astringent or stuck in the valve guide, and the valve cannot move up and down. The valve spring loses its elasticity or breaks.

Diagnosis and exclusion: After eliminating the cause of the failure of the intake and exhaust system and the fuel system, the cylinder pressure can not be determined when the failure is measured, the cylinder pressure or the intake manifold vacuum can be measured, and the failure can be more accurately determined. When the cylinder pressure is measured, The cylinder pressure of valve leakage is lower than other cylinders.

If you encounter engine failure during transportation, you must promptly go to a professional maintenance service site for inspection and find the root cause for maintenance in a timely manner. Judging and mastering the causes of engine failures and troubleshooting methods can reduce potential safety hazards while driving. At the same time, regular maintenance and repairs at professional service stations can make the engine service life longer.