Afternoon,

It seems like all threads are about auto transmissions. I changed the fluid in my 190d 5 speed a couple months ago (.7 qts). A couple weeks ago I noticed a small spot on the floor of the garage. I looked under the car and on the drain plug of the transmission some fluid was hanging on getting ready to drop. I tighten it up some more, and wiped it clean to verify no leaking the next time I check it. Today I did check it and it was still a drop read to hit the floor. I tighten it up a little bit more. Since the transmission and plug are made of aluminum I'm am worried that I could strip the threads if I tighten it any more. Would it be ok to unscrew the plug about half way and put some type of locktite/gasket sealer on the threads in hopes that will stop the leak? Changing the transmission fluid will never happen again in my life time, perhaps my son will. Thanks for reading this.

Hugh Sr

1984 190d (W201) 94,834, great shape

not sure about the manual tranny, but I believe on the autos there is a crush washer on the drain plugs. Perhaps you need a new one?

No, its just your every day run of the mill aluminum drain plug.

Hugh Sr.

1984 190d (W201)

hmmm... try some teflon tape on the plug?

I think there is supposed to be an aluminum washer there. Do not use a thread sealer or teflon tape as the threads are not the sealing surface, the face is. You will cause a worse leak doing it that way, plus whatever excess winds up inside the transmission.

This sounds to me like the drop is not in fact transmission fluid. It's blowing back from something leaking up in the engine area (I've never yet seen one of these that didn't drip something from somewhere), blowing back along the car until it pools there, and that's just where you're seeing the drip form from elsewhere.

If this isn't true; if you have finger-tested it and established that it's gear oil without a doubt, then forgive the suggestion. But half of the things I think are leaking are actually just residual drips from elsewhere.

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

I just read your post and through the other posts in the thread and then I went and checked a 5 speed tranny from a 84 190D I've got in my shop and the one I have uses aluminum crush washers on both the drain and fill plugs, the plugs are steel with recessed Allen heads and a rimmed flat underhead that sandwiches the crush washer between the case and the plug. Prehaps the plugs on your tanny have been changed from the originals, if so you will never get them to seal because it's straight thread.