During scavenge space inspection, following items especially related to piston rings must be inspected:
- Check condition of sludge for any metal particle
- Check whether flap valves through which air enters scavenge space is free or not
- Check Piston Rings ( for good piston ring Condition)
When good and steady service conditions have been achieved, the running surfaces of the piston rings and cylinder liner will be worn bright (this also applying to the ring undersides and the “floor” of the ring grooves, which, however, cannot be seen). In addition, the rings will move freely in the grooves and also be well oiled, intact, and not unduly worn.
The ring edges will be sharp when the original roundings have been worn away, but should be without burrs.
Check Piston Rings for Micro-Seizure
Causes and symptoms of piston ring seizure
lf, over a period of time, the oil film partially disappears, SO that dry areas are formed on the cylinder wall, these areas and the piston ring surfaces will, by frictional interaction, become finely scuffed and hardened, i.e. the good “mirror surface” will have deteriorated.
In case of extensive seizures, sharp burrs may form on the edges of the piston rings.
Effect of piston ring seizure
A seized surface, which has a characteristic vertically-striped appearance, will be relatively hard, and may cause excessive cylinder wear.
Due to this hardness, the damaged areas will only slowly disappear (run-in again) if and when the oil film is restored. As long as the seizure is allowed to Continue, the local wear will tend to be excessive.
Seizure may initially be limited to part of the ring circumference, but, since the rings are free to “turn’ in their grooves, it may eventually spread over the entire running face of the ring.
The fact that the rings move in their grooves will also tend to transmit the local Seizure all the Way around the liner surface.