Post On 2019-10-13

Oil Leakage of Valve Seal

Valve seal and piston ring are the most common problems causing oil leakage. There are two simple ways to distinguish between judgments:

(1) Measuring Cylinder Pressure

The wear of piston ring is determined by cylinder pressure data. If the wear is not serious, it can be repaired automatically by adding additives.

(2) Is there blue smoke in the exhaust vent?

Blue smoke is a phenomenon of oil combustion, which is mainly caused by piston, piston ring, cylinder liner, valve oil seal and wear. But the phenomenon of oil combustion caused by exhaust pipe must be eliminated first. The damage of oil-water separator and PVC valve can also cause oil burning. In order to judge whether the valve oil seal leaks or not, the way of throttle and pine throttle can be used to judge whether the exhaust port of the gas valve is worn too much by piston, piston ring and cylinder liner; blue smoke phenomenon is mainly caused by valve oil seal damage and valve duct wear.

Consequences of valve seal leakage

Valve oil seal will burn in the combustion chamber. If the valve oil seal is not tightly penetrated into the engine oil, the exhaust will show blue smoke. If carbon deposit is easy to occur in a long period of time, the tightly closed valve will appear and the combustion will not be sufficient. It can also cause carbon accumulation in combustion chambers and nozzles or blockage of ternary catalysts; it can also cause engine power decline and fuel consumption to increase significantly, damage to related equipment, especially spark plug working conditions to reduce significantly. New valve seals should be replaced as soon as possible.

Several common causes of oil spill:

(1) Reasons for assembly

Pressing is not in place, resulting in deformation of oil seal after pressing.

In the assembly process, the oil seal scratches through threads or splines.

Low roughness of oil seal position and excessive pressure lead to spring failure.

(2) Skeletal causes

Because of the material problem of oil seal spring, its performance fails. Spring failure forms are: the spring is too tight or too loose, when too loose, the spring compression force is small, can not achieve sealing effect, when too tight, the spring compression force is large, the oil seal and the rotation shaft are not properly matched, resulting in abnormal wear and tear of the oil seal, and eventually oil leakage occurs.

(3) Reasons for working media

The choice of oil seal material should consider its compatibility with oil. The poor compatibility of the two materials will cause lip swelling, hardening, softening, cracking, and eventually oil leakage.

(4) Causes of lip wear

Cleanness problems: abnormal wear and tear occurs when casting sand, machined iron scraps, oil impurities, etc. are accumulated in large quantities.

The oil seal position is different from the rotating shaft, and wear occurs after the oil seal is pressed and packed.

The lithium grease at the lip of the oil seal is not lubricated well, and dry friction will occur, leading to wear and tear.

(5) Reasons for Axis

The surface roughness and hardness of the rotating shaft are unreasonable. At present, the roughness is not less than 0.8 in automotive industry. High frequency quenching is used in the oil seal matching part, and the hardness is not less than HRC55.

There are defects on the surface of the rotating shaft, such as corrosion, scratch, directional knife marks, etc.