Oil drain plug leaks

Can’t stop my oil drain plug from dripping. I tried to seal it with permatex #2 which did seem to work for a week then drips again. As a last resort I bought the fancy 200 dollar plug with the vent, it leaked also and it has a fancy copper gasket. It’s not a bad drip but enough to piss me off. Probably drips an ounce in a month. Any one have any ideas?
I only see oil where the plug meets the case, nothing above or around. I’m thinking next go around I might try Teflon tape.

No teflon tape. That’s for pipe threads.
Loctite 518 on both sides of a good washer is leak free.

so this fancy $200 plug with vent and fancy copper gasket... did you anneal the copper before installing? picture might help.

A gasket can only work properly on a surface that is friendly to it.

Is the engine case gasket surface in good condition ?
Is the thread in the engine case in good condition to take torque. <<<<<

What about a Stat O Seal or something similar, for oil to escape it needs a path to do so.
Find the cause that created the symptom.

My solution was to make an aluminum sleeve that replaced the copper gasket.

I use a 3/32 x 1-1/8 ID Oring that fits around the sump plug. The aluminum spacer fits around the outside of the o ring and is about .010” shorter than the oring so the oring gets slightly crushed.

I use a similar setup on the fork drains but much smaller of course.

Are you sure the leak is not originating from elsewhere and making its way down to the plug?

$200 fancy plug or not, the sealing arrangement is a simple affair of clamping a sealing washer between plug and case.

The sealing washer that comes with the breather plug is a crush type, which seal very well and allow for minor imperfections too.

There are other potential leak points with the breather type plug though of course, the internal oil ring, the retaining screw tightness, the banjo bolt.

But if yours leaked before, chances are the current leak has the same root cause.

IF the faces are good, undamaged and aligned, and IF the plug is tight, it WILL seal. It has no choice!

So, I’d say that either something else is wrong down there, damaged faces, crack in the case, etc. Or the oil leak is originating higher up and making its way down to the plug.

Does it leak while just sitting or only after a ride?

Fast Eddie said:

Are you sure the leak is not originating from elsewhere and making its way down to the plug? ......

Click to expand...

Fast Eddie speaks truth here. You have to carefully wipe everything and catch the leak at its origin (as it begins to leak) to be sure.

I can see it oozing from the plug and I have sprayed
Arrid extra dry around it and see no signs. I’m quite sure it’s the plug. When I seal it it stops for a week or more. I have another Norton that doesn’t leak a drop and I tried swiping plugs with no luck. I think I’ll try the lathe and o ring next.

The problem for me has been the copper washer on the plug. If you get one from an auto supply store they are too thin, typically 20g instead of the 14g (?) AN washer. Then they deform too much when crushed.

For the thin ones, a bit of teflon on the outermost threads on the plug cures it.

I think I'm going to install a Dowty sealing washer on mine.