Upside down Piston ring

Posted by Ashley Wilson on

These picture below indicates a compression ring that has being fitted upside down or has been expanded excessively


The main task of compression rings is to prevent the passage of combustion gas between piston and cylinder wall into the crankcase and also allows up to 50% of the heat transfer from the piston to the bore

If a tapered /keystone top ring is fitted incorrectly.  The ring does not have radial movement in the ring land, and an oil carbon layer will form making it abrasive and causing excess wear. The pictures below indicate were this wear commonly occurs

The Bevell wear this has made in this cylinder bore picture below is amazing, as it behaves as a ring compressor. By relocating the ring back into the piston ring land on every down stroke. The compression ring is no longer floating on a fine film of oil and it comes to a metal contact on the cylinder wall causing this unusual wear effect.  This wear can be caused by compression heat burning the rings with no heat dissipation at that location, also abrasive metal to metal wear, other symptom’s you will get besides excessive wear is piston ring flutter and high oil consumption, lack of power, smoke and much more.


Serve piston ring damage occurs when the ring are not fitted correctly. Put upside down, fitted to the wrong ring land, incorrect size and type, or bent back to far trying to fit the rings by hand as re just some of the major causes. Always use a ring expander as this governs how far a ring can be expanded


** Note a general rule of thumb – when fitting pistons & rings correcting and using a ring compression tool you should be able to push in with your thumb. But a hammer handle only it fine.


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