Seizure due to lack of lubrication on the piston skirt
DESCRIPTION OF THE DAMAGE
- Seizure marks on the piston skirt on the pressure side, which in some cases extend into the piston ring zone.
- Slight seizure marks on the anti-thrust side.
- Surface of the seizure areas is light-coloured and has an almost pure metallic finish.
DAMAGE ASSESSMENT
There was an acute lack of lubricant between the piston and the cylinder bore. The fact that the surface of the seizure areas has an almost pure metallic finish indicates that the oil film was present but significantly weakened at the time of the seizure. Due to the limited extent of the damage, this concerns a temporary lack of oil or the early stages of damage. The damage would have been even more severe if engine had been operated further.
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NOTE With this type of seizure due to lack of lubrication, the damage area is always located in the area of the piston skirt where the normal wear pattern would have formed on an undamaged piston after running in. |
POSSIBLE CAUSES FOR THE DAMAGE
Insufficient lubrication caused by:
- Insufficient engine oil.
- Oil pressure in the engine too low (oil pump, pressure relief valve, etc.): not enough oil emerges at the crankshaft bearings. This means that not enough lubricating oil is supplied to the cylinder running surface, which is lubricated with splash oil and centrifugal oil from the crankshaft.
- Failure of the oil injection jet for cooling the piston.
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