VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Oil Drain Plug Leak

Every time I look under my car, I see a drop of oil on the drain plug as well as the floor. I've seen copper washers and nylon washers used behind the plug. What are you using that works?

I have a nylon washer on my 2003 GMC Envoy with no leaks. I have a copper washer on my 1931 Sport Coupe, but I did replace the plug due to corroded threads. No leaks now.

Are you absolutely sure that the leak is at the drain plug? Chev's have been known to leak around the side cover gasket a very small amount. When sitting,that leakage will seep down the side of the block then "weep" along the oil pan until it finds an obstacle ( here, the drain plug ) where it will gather and eventually gather enough to form a drop. Onto the ground it goes!
My suggestion would be to thoroughly clean the block and oil pan exterior surface below the side cover, drive the car a bit, then let it sit and later observe the cleaned areas to see if they are still completely dry.

I always put a copper or nylon washer on sump plugs and rarely had any leak but they all leak without the washer.
Tony

If the washer is a loose fit on the plug you can fit an oring that is just slightly thicker than the washer. The washer will limit the crush on the oring and also that set-up can reduce the temptation to over tighten the plug.

To Steve's point my wife's car uses a captured o ring in an aluminum washer. I have started using them when ever I get a leaker and the leaks stop.

Dave

Great tip Dave, I also have a couple leakers. Where do you source the captured o rings? Thanks, Mike

I bought them first from a Saab parts place like E Euro but I did find them locally. Maybe Dorman but I will see if I can find the source.

Dave

I am sorry I can't remember where I got them but the picture shows the small ones I bought for the Saab, larger ones in my Triumph motorcycle stuff and changing the oil on my Duramax this morning there is a third size. So they are out there , when I get time I will look for their source.

Dave

ps These don't look alloy to me but I do remember using some that were but you can't trust my memory!

Dave, Thanks for the information, I’ll do some digging myself and let the group know if I come up with anything. Mike

They are called a bonded seal, Dowty washer. EBay and amazon are your friend

Steve, in what order are you talking about? Does the "O" ring go up against the oil pan and the washer & bolt go next?

I put the oring on the bolt and then the washer . On a lot of the plugs the washer fits loose allowing a gap on the inside. The oring should be just slightly thicker than the washer filling the gap. If you can find one of the "bonded seal" washers the oring is attached to the washer hence its name "bonded seal washer".

My local Advance Auto Parts has Dorman brand bubble packs of oil drain plug washers in various sizes. In the package for the 1/2” size, there were 5 different washer types, one of which was a bonded seal washer. I installed it a couple days ago and the drip stopped. Fortunately I had a spare plug and only lost about a cup of oil doing so.

I finally got a chance to drain the oil and take the drain plug to my local NAPA store. I bought a new drain plug (just to have one if the original ever falls off, LOL) AND the bonded seal. I installed the seal with the old plug and added 2 quarts of new oil. I'm going to give it until next week and see if any of the new oil is coming out. I originally had a composite type of washer (not nylon) that probably caused the leak. Oil was not running down from the top of the engine, just at the drain plug. Attached are several photos showing the drip, the old plug with that composite washer and the new stuff.

Sorry for my confusion. Is the picture showing the drip the old drain plug and washer?

The middle photo shows the composite washer and original drain plug. The top photo shows them installed and leaking.

In the middle photo of the plug it appears to have a rough surface. Also you can see the recess between the end of the thread and the face. That is where the oring if used should sit. I would either use the new plug or clean up the surface of the old plug if using it.