The MGA With An Attitude

At 09:03 AM 10/30/05 -0700, Kurt Petty wrote:
"I installed the spin off oil filter. Since then it has leaked, not much but a leak is a leak. I removed the entire spin off attachment and installed new gaskets everywhere, tightened everything and bent the little tab over and installed a new filter. Fired the car up and it still leaks. It seems to be leaking where the spin off attachment and block meet."

oil filter mount on engine block This is a common problem with an easy fix. Look at the joint where the filter mount attaches to the engine block. There is a flat bottom groove around the perimeter which accepts a square section rubber O-ring. Early production oil filter canisters had a one piece shell with a single O-ring here (and a slightly smaller one inside the canister). Later production filter mounts were two piece with a short base section next to the block and the canister below that. Those units used two identical O-rings, one at the block connection and one between the parts of the filter mount. The accessory spin-on adapter uses just one O-ring at the engine block.

The problem is that over a long period of time the rubber O-ring will go hard like burnt on carbon. This is especially true with the two piece canister assemblies where the top O-ring may never be changed for the life of the engine. When someone does get around to installing a new O-ring, remnants of the old O-ring might not be removed, and the new O-ring may be placed on top of the old hard one. Stacking two O-rings into the gland can result in a leaky joint.

The solution is to remove the old O-ring from the gland, which may be easier said than done. The thing is likely to be rock hard and smooth as glass, black in appearance and difficult to see. Many people will have a close look and believe the groove is clear, even when the old O-ring is still stuck in there. To get it out use an ice pick or a sharp pointed screwdriver to prod at it vigorously to dig through it, break it up into small pieces, and dig it all out until you have a clean groove all around. Then install a new O-ring and reassemble the filter mount. For all the cases I know about, a leak at this joint is always the same problem, always has the same solution, and it will always seal up well after the clean out and proper installation with a single new O-ring.

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