The oil drain plug in my pan is already oversized, thanks to the previous owner. Even with a new o-ring it still drips. What's the best fix? tap for the next size up? Replace the pan? Fatter o-ring?

 

Well it is winter, I think I would lean towards getting a new pan and fixing it once and for all.

But have you tried some sealant on the threads?

 

No not yet. It looks like the dang pans are $300+. Kinda silly to spend that much money on just a stripped drain plug hole.I wonder if it can be tapped to a larger size drain bolt? But even if so, I should drop the pan to do that as well.

Not really sure how this combined transmission/engine oil pan set up works, or if it can be dropped with the engine in place.

 

Depending on how much meat you have left (based on you mentioning it is already an oversized plug). I would take some measurements and come up with the next size that can be successfully tapped, be it metric or sae.

There is always the opportunity to pull the pan and have a welder weld the bung up, then drill and re-tap, but to me that is when all other options have been exhausted.

 

I read a couple other threads on here about oversized plugs and that they require a special metal and rubber sealing washer. I'm using the OEM o-ring which seams too small and thin to do the job. The threads I have seem to work just fine.

 

If the drain plug and the pan threads are in good shape. You could maybe try a thin crush washer under the head of the bolt as well as the stock O ring. The crush washers are normally aluminum, some even have an O ring built into the washer.

Just a thought,
Tom

 

That's the plan- I'll find a rubber/metal crush washer thing. If that doesn't work, this kit looks promising as it adds steel threads: https://www.wiseautotools.com/time-s...um-pan-1-2-20/

It's a little pricey though and I'd have to buy another OEM drain plug. But it'll be better than new.

Maybe this for a drain plug gasket:

 

The Amazon link is for the crush washer with O ring that I mentioned. That one is a bit pricey, but it is Dorman. You can find kits of the same type washer with multiple sizes for about the same price if you may have use for other sizes.

Might be cheaper to have a shop fix the threads with an insert, rather than buying the kit for a one time use. Timesert is a very good thread repair, but pricey.

Hope the crush washer solves the problem!
Tom

 

Thanks, I'll try the Dorman first. If it still leaks, I'll buy the timesert set up. I'd rather buy the expensive tool kit and have it myself rather than let a shop touch my toys. I still have the $150 Ford 5.4 triton spark plug removal kit from a long departed F250, but if I ever have to change plugs on a 5.4, I'm ready!

 

Ah. Another tool junkie. Your in friendly territory here

You say it already has an oversize plug. (?) If so, you might be disappointed with a 12mm washer since the original plug was 1/2-20 (12.5mm) and the oversize is possibly 9/16. Depends what kind of plug they used - as in self tapping or what. Might want to measure before ordering. A copper washer heated cherry red then cooled (water or air) will soften it up and make for a good seal or aluminum if you can find one the correct size.