How to Inspect Piston Rings, Treatment and Causes of Piston Ring Failure In Marine Engines
Proper working of the piston rings is of extreme importance for the efficient operation of a marine engine. Marine engines are designed for high power outputs and bad piston rings can seriously affect the performance of the marine engine.
Reasons for piston ring failure
1) Piston ring and groove clearance is insufficient because of which the ring can jam in the groove leading to blow past and breakage of ring.
2) Cylinder liner has been excessively worn down.
3) Cylinder liner lubrication is not sufficient.
4) Piston ring has worn down excessively.
5) The cylinder liner and piston diametrical clearance has increased.
The exhaust and scavenge ports of the liners are not properly radiused because of which the ring receives a shock when it slides past the port edges.
Treatment of piston rings
1) Copper plating.
2) Ferox coating and phosphating.
3) Piston rings are coated with chromium plating.
4) Plasma coating.
Inspecting piston rings
1) See that the piston ring surfaces have a bright finish.
2) They should not be worn down.
3) The rings should be well oiled.
4) The rings should have sharp edges and not have burns.
5) Check for appearance of vertical strips or sharp burrs.
6) Check if there are a large deposits of thick carbon because of which the rings cannot move freely in the grooves.
7) See for dry black areas on rings and liners.
8) Elastic tension in the rings should be checked.