Found my Transmission Leak

[xsports33]

I thought it was coming from the pan bolts, but it's actually coming of of this circle shaped thing and dripping down. Also, my entire exhaust piping is covered in ATF and when i come to a complete stop you can see smoke coming from underneath the car. It's all the ATF burning off the pipes.

any ideas on how to fix it? can i just buy the piece that's leaking and replace it or do i have to replace a lot of the transmission?

 

[xsports33]

Forgot to add. it's a '95 BMW M3

 

[Colt45ws]

Looks like its probably a servo of some sort.
To me it does look removable, but I'd bet that its controlling a band and when you remove it, the band will drop or move out of position.. Fixing that probably involves removing the valve body so you can use something to hold the band in place while you R&R that part.

 

[Johnny]

Has a BMW dealer looked at it? Might get an estimate from them, but be sure your setting down when you do.

 

[lewdwig]

Time for some Trans Medic!!!

 

[mechtech2]

I don't know for sure how that part is taken off or held in.
A good silicone RTV applied externally will seal it for years, however. So will the more permanent JB quick Weld.
But the substrate has to be really clean and free from any oil.
Let it cure and you'll be good for a long time.

See if BMW has anything to say about it. Maybe you'll get lucky and get a free fix. Or maybe they'll have some other specific fixes.

 

[caravanmike]

if it is the 4l30e that looks like the accumulator piston cover. very common leak point, just ask a rodeo owner. i believe it takes a special snap ring pliers to handle it. mike

 

[xsports33]

I never go to the dealer, i always do my own work. It's my "project" car and non-daily driver.

I REALLY like the RTV silicone idea. I was thinking about that before, especially since it feels like the part is some sort of hard rubber.

I'm not sure if it's the 4l30e. I do know it is a GM transmission with a front fluid compartment and a larger rear fluid compartment. the leak is above the front fluid compartment and an accumulart piston cover sounds right. I can see the snap rings holding it down, so i know that's how i'd remove it. i'm hesitant though because i don't what's behind it and if it's holding anything in place. Can i just replace the piston cover?

 

[paulo57509]

I would never had guessed that BMW would source transmissions from GM.

 

[mechtech2]

xports - Remember the CLEAN part. A bit rough and CLEAN.
Then your RTV will work, if you let it set up.
Don't use clear aquarium sealer - use good stuff.
And you want to apply it to the surrounding area - don't be cheap.

This will work for seepage, not a high pressure leak.
But the more permanent JB Quick weld will hold pressure.

 

[Robenstein]

I can vouch for JB weld. I knew a fellow that cracked his block and employed JB weld to seal the external crack. Lucky for him it only cracked on the outside. Lasted two racing seasons that way. He now puts enough anti freeze in to make sure that if the heat does go out in his garage, his big block wont die.

I just just it like bondo on guns I refinish before applying a teflon finish.

 

[caravanmike]

Originally Posted By: paulo57509
I would never had guessed that BMW would source transmissions from GM.
they not only sourced them once, but multiple transmissions over multiple models.

 

[tig1]

Originally Posted By: paulo57509
I would never had guessed that BMW would source transmissions from GM.


A friend has a 95 JAG AND IT HAS A GM TRANNY. HAD IT REBUILT LAST YEAR.

 

[xsports33]

Mike - You're a Genius! I definitely owe you a six pack! i called around to BMW dealerships for the Accumulator Cover and they wouldn't sell me "just" the cover, but the entire servo kit with spring, piston, and cover and quoted me close to $400... I called some Isuzu dealerships and one local spot had Accumulator cover for a grand total $14. It took a a few hours to do the swap, but you saved me some serious ca$h and heartache.

Thanks again!!!

Also, after removing the old piece and examining it; the crack was only a 1-2mm long and some RTV or JB weld would have done the trick! But, i would been worried about getting RTV into the transmission and kept pondering the "what ifs". Better safe than sorry i guess. Glad i replaced the entire piece.

 

[mechtech2]

It is good that you put the new piece in - nice work. This is the preferred fix.
But it easily could have been pure heck, depending on the design.

 

[Gary Allan]

Originally Posted By: tig1
Originally Posted By: paulo57509
I would never had guessed that BMW would source transmissions from GM.


A friend has a 95 JAG AND IT HAS A GM TRANNY. HAD IT REBUILT LAST YEAR.




The first Austin Martin V8 came with a GM 350, iirc. It was much more reliable and much cheaper than anything available over there. That was back in the 70's

 

[mechtech2]

Rolls Royce used Gm400s.

 

[Jerryb]

Congratulations on your repair! I love it when people fix things and keep their cars running without going to the dealers. You keep a simple job simple. I also like the help from people on this forum. Good job.

 

[caravanmike]

great job! Mike