The Problem | Ringland Failure on EJ20 and EJ25 Series Engines
While largely limited to the late model WRX and STI with the EJ255 and EJ257 motors, theres been some concern raised about the shear numbers of ringland failures being reported on the forums. Our goal with this article is to address why this is likely occuring and how you can guard yourself from it happening to your Subaru. Some of these may seem like common sense to most, but for many younger or first time turbo car owners it may be new.
The “ringland” is the portion of a piston that supports the ring itself. The standard Subaru EJ piston will have three ringlands per piston. The first is the most susceptable to damage because it is supporting the primary compression ring. This ring is what seals out the majority of the heat and combustion gases from the crankcase. The second ringland supports the secondary compression ring which is shaped differently from the first ring. It is tasked with ensuring that the remaining combustion gases don’t get past and also to scrape any oil that has gotten past the third ring off the cylinder walls. The last ring is known as the oil control ring. It is shaped completely different from the two compression rings because it’s duty is to force oil into the various parts of the piston to help cool and lubricate it.
Ultimately for one reason or another the ringland is cracking and failing.
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