Oil drain plug leak....?
 

Been trying to figure this ever-so-slow oil leak. Tiny drops surround the drain plug and spots the floor. Takes a few days to show up on the plug and floor after wiping clean. Changed the drain plug to a new one last fall, but same results.
Since this car is so low to start with, I wonder if previous owner may have slightly hit the front of the pan or plug just enough to mushroom the pan around the plug, and maybe the plug doesn't tighten up flush?
Anyone had this issue? Leak is definitely from plug area.:bigears

You can start by replacing the o-ring gasket if you have not done so already.

yup my gasket broke on mine and it started leaking so i went with a magnetic bolt

Did the new plug have a new seal on it? Take a close look for any cracks as well.

yup...first thing I tried was a new seal, then a new plug...no luck.

It sounds like the sealing surface, on the pan drain tapping itself, is not smooth and flat.

Try a soft copper sealing washer on the drain plug in place of the rubber seal.

When you had the plug out, did you inspect the oil pan surface to see if it looked smooth?
If the rubber gasket will not seal, I doubt that a metal gasket will seal.

Last fall during the oil change and plug change I believe I only concentrated on the plug, as I dont recall seeing anything unusual with the pan. Will be changing oil soon, so inspection of the pan will be next. I'm thinking its "sort of mushroomed or slightly crunched" just enough to not seal correctly, otherwise I have no clue what it could be.

I also changed to a magnetic plug and later noticed some slight leakage. I loosened the plug and applied some thread sealer to seal it up. (Didn't want to drain all the oil again.) No leaks now, but will need to check it out next oil change.

yup...I actually included teflon tape on the threads when new plug was installed....drip...drip...drip :smash:

The plug has straight threads, not tapered threads like pipe fittings have. Teflon tape works best on tapered threads.

A thin coating of black silicone RTV over the rubber seal, before you install the plug each time, should stop the drip too.

:iagree: but there must be something wrong if that is necessary?

There has to be a casting flaw or an irregular surface in the lower oil pan section, at the drain plug hole tapping. You'll have to drain your oil to do a close inspection of the area.

Look for any nicks or burrs in that area, and remove them with a Dremel tool.

Well...the leak is back.....:banghead:..after draining oil, and inspecting pan a few months ago, I delicately filed the surface around the hole to ensure the surface was flat...installed new drain plug with seal. About a week ago started smelling the oil again ever so lightly sprayed over the bottom of the oil pan. Yet this time, no drops on floor. Smell is worse the more I drive especially at highway speeds.....is it time to change oil pan????:bigears

When I changed my oil I cleaned off the teflon tape and put on a thicker O ring. That solved it for me. You could also try "Gasket Eliminator" on the threads or maybe the oil is coming from somewhere else and running down to the plug? You probably already checked that tho.

yea, I've tried it all...inspected quite a few times, thread sealers, new gaskets etc., the only thing wet with oil is only around then plug.....out of options I guess...:smash:

Get a new magnetic drain plug and use a new o-ring nylon gasket. This worked for me several years ago. Make sure the leak is from the drain plug and not the pan or elsewhere.

An idea...........Use a tap to restore thread or create new thread or buy a specially made oversize drain plug from an auto parts dealer. The one you want is designed to rethread damaged threads in the oil pan, allowing the new plug to seat properly and seal the leak. Start the plug into the drain hole by hand, and then use a wrench to seat the plug. Stop turning as soon as the plug is secure.

Different seals/washers require different torque requirements, depending on the material they are made of; do not overtighten...do not undertighten.

I have heard chrome plugs work best.

777

777

All these ideas are good ones, but have been tried.....I am almost certain oil pan must have been "mushed" at one time by previous owner thereby causing the drain hole not to be round (cannot see this by eye, BUT- there is a "flat spot" at the very bottom of the hole in the pan..)not sure if this was cast this way or been hit......
the drip is so slow it takes weeks to appear...maybe trade this in for a C6....

There you go. Problem fixed!!:cheers: