When the maintenance technician was replacing the oil filter element, he discovered that the old engine filter had become "fat"!

Note that in this case, even if you replace the new filter, it may not solve the problem. You must find out the root cause, otherwise there will be endless troubles.

Possible causes of swelling and deformation of the oil filter

1. The bypass valve fails or an inferior machine filter is used.

In order to prevent the engine parts from losing lubrication due to clogging of the oil filter element, a bypass valve is installed inside the engine filter or on the filter seat.

If the engine filter is blocked due to extended use and has not been replaced, and the oil pressure is too high, the bypass valve in the engine filter will open, and the oil will enter the engine lubrication oil passage without filtering.

If the oil bypass valve is damaged, or a low-quality filter with poor opening performance or even no bypass valve is used, the filter paper will become clogged, which will easily cause the oil pressure to be too high, causing the filter to swell.

In addition, the metal shell of some inferior machine filters is relatively thin, and the internal pressure will gradually cause fatigue of the shell.

2 The engine oil is dirty or has too high viscosity

If the engine oil has not been replaced for a long time, it will carry a lot of metal shavings, carbon deposits and other impurities inside, and the fluidity will be poor, which may increase the oil pressure.

In addition, if the viscosity of the oil used is too high, the slow oil flow rate may also cause the oil pressure to increase, causing the filter housing to deform.

3 Oil pump pressure limiting valve stuck

In order to keep the oil pressure relatively stable, a pressure limiting valve is installed on the oil pump. When the oil pressure is higher than the standard value, the pressure limiting valve will open and the oil will flow back into the oil pan.

Therefore, if the pressure-limiting valve becomes stuck and the oil pressure cannot drive it to open, the problem of excessive oil pressure may occur, which may also cause swelling of the filter housing.

4 other possible reasons

The crankcase ventilation valve is damaged, causing the pressure in the crankcase to be too high; the oil passage is blocked by sludge, coked oil or metal debris; the clearance of pressure lubricating components such as main bearings or connecting rod bearings is too small, affecting the flow of lubricating oil, etc. All of them may cause the engine oil pressure to be too high, leading to the deformation of the engine filter.