Transmission fluid slowly leaking out of the drain and fill plug

[Epsilon]

I noticed oil slowly seeping out of the fill and drain plug from the transmission. I've tightened the bolts as much as I could from under the car and it still happens throughout a week's time while the car sits idle. I've cleaned the area multiple times to confirm it was dry by wiping away the wetness from the exposed threads.

A search from the internet revealed an updated drain plug from the E39M thread, same plug as E46M, but I don't recall this being an E46M problem.

Found the attached pdf from the E39 thread, but it only appears on the early model E46s.

Wanted to throw this out there before I get new plugs and test.

[Lukem3]

Just needs new crush washers, time for a service

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[sapote]

Just needs new crush washers

They are pipe threads and no washers ever used on pipes.

[Lukem3]

Apologies new bolts* typed faster than i was thinking.

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[sapote]

. I've tightened the bolts as much as I could from under the car and it still happens

tighten too much could crack the threaded holes and they are tapered pipe thread working like a wedge. If leak, just wrap white pipe tape (teflon) couple turns.

[heinzboehmer]

Just needs new crush washers, time for a service

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Transmission doesn't have crush washers on the plugs, you're probably thinking of the diff.

Edit: typed too slow and didn't see your second post before posting mine.


OP, did you check the torque with a torque wrench? Torque spec is 38 ft-lb, which is not crazy high, but maybe not something you'd get to while on your back and using a small ratchet.

Other thing to point out is that the fill procedure for these transmissions is to fill them up until fluid starts coming out of the fill hole. If fluid is weeping from the fill plug, then the transmission might be overfilled. Worth checking if you're going to swap the plugs out.

[Epsilon]

tighten too much could crack the threaded holes and they are tapered pipe thread working like a wedge. If leak, just wrap white pipe tape (teflon) couple turns.

Thanks, I'll give that a shot. I had thought about teflon tape, but didn't know if it could tolerate heat.

[Epsilon]

OP, did you check the torque with a torque wrench? Torque spec is 38 ft-lb, which is not crazy high, but maybe not something you'd get to while on your back and using a small ratchet.

Other thing to point out is that the fill procedure for these transmissions is to fill them up until fluid starts coming out of the fill hole. If fluid is weeping from the fill plug, then the transmission might be overfilled. Worth checking if you're going to swap the plugs out.

Was looking up procedure to fill and torque spec, but looks like you answered it. Thx bud!

Is it 37 or 38 ft-lb? This site says 37.

[DoubleSidedTape]

Was looking up procedure to fill and torque spec, but looks like you answered it. Thx bud!

Is it 37 or 38 ft-lb? This site says 37.

I’d guess it’s 51 Nm, which is somewhere between 37 and 38 ft lbs, and you are seeing people round it differently.

[heinzboehmer]

Is it 37 or 38 ft-lb? This site says 37.

TIS says 52 Nm, so 38.35 ft-lb if you want to be super precise

[sapote]

Thanks, I'll give that a shot. I had thought about teflon tape, but didn't know if it could tolerate heat.

Teflon Don cooked in a teflon pan.

[cobra]

I used some Gasoila on the threads of mine and they are perfectly dry. No need to torque them super hard. https://www.amazon.com/Gasoila-Soft-.../dp/B00CRKWAXQ

That said my transmission is leaking at the case halves so... kind of a bitch to fix that one.

[Slideways]

Here is an example of M539 (pretty knowledgable M5 owner) using thread sealer for the drain and fill plug on the 420G gearbox:

[nextelbuddy]

I used some Gasoila on the threads of mine and they are perfectly dry. No need to torque them super hard. https://www.amazon.com/Gasoila-Soft-.../dp/B00CRKWAXQ

That said my transmission is leaking at the case halves so... kind of a bitch to fix that one.

same here. Mine has a leak between the bell housing and the gear box..

i plan on doing my clutch in a few weeks and while the trans is off i'm going to use HONDABOND between the bellhousing and gearbox since there's no gasket there.

i THINK i may have a leak between the 2 halves of the gear box but i cant be sure (thats harder). it almost always seeps between the bell housing and gearbox for me.

[oceansize]

same here. Mine has a leak between the bell housing and the gear box..

i plan on doing my clutch in a few weeks and while the trans is off i'm going to use HONDABOND between the bellhousing and gearbox since there's no gasket there.

i THINK i may have a leak between the 2 halves of the gear box but i cant be sure (thats harder). it almost always seeps between the bell housing and gearbox for me.

Same for me. I'll tackle sometime this summer.