Transmission leaking oil at case joints

[CrookedCommie]

I cleaned, brushed and ran a bead of RTV around and up the sides. Was dry after that. Used painter tape to make it nice and even.

[nuc1]

On mine I'm also wondering if it's leaking from the input shaft seal. I'm not sure if a leak from the input shaft seal would show itself as a leak between the casing.

In my case I already purchased a brand new input shaft seal and all the parts associated with the clutch job like the guide tube etc and all those parts.

Mine had an input shaft seal leak. Looked like a rear main seal leak as it would come out between the bellhousing and motor. 115k on the transmission fluid didn't help trying to see if it was motor oil or tranny fluid.

Also I now have the same leak where the tranny halves bolt up. It doesn't drip but does weep. For now just watching it until I get the knowledge to pull it apart.

Mike

[nuc1]

I cleaned, brushed and ran a bead of RTV around and up the sides. Was dry after that. Used painter tape to make it nice and even.

How many miles since you did this? Seems the non-invasive route may work. Not really wanted to split the transmission apart unless I have to.

Mike

[CrookedCommie]

Ran it for about a year on the track car. The better you clean up the better the rtv will adhere. Like has been mentioned you don't lose enough to affect the level but it helps keep things dry.

[nuc1]

Ran it for about a year on the track car. The better you clean up the better the rtv will adhere. Like has been mentioned you don't lose enough to affect the level but it helps keep things dry.

Ok thanks.

Mike

[Gt4]

Sometimes a CPV leak look like a transmission leak. I never had transmission leak on my 17 E46 M3 except on selector rod seal.

[bigjae46]

So while it's out, I planned on separating the bell housing to reseal it or something like Honda Bond or the like.

Anaerobic gasket maker is what you want. Toyota uses it. BMW uses it on the B series engines as well.

I use it to seal up diff covers...its much easier and faster than RTV.

[cobra]

OP, any updates on this? I'm about to pull my transmission for a twin disc clutch job. So while it's out, I planned on separating the bell housing to reseal it or something like Honda Bond or the like.

On mine I'm also wondering if it's leaking from the input shaft seal. I'm not sure if a leak from the input shaft seal would show itself as a leak between the casing.

In my case I already purchased a brand new input shaft seal and all the parts associated with the clutch job like the guide tube etc and all those parts.

- First I thought it was the drain/fill plugs and so I used Gasoila on the threads. Still leaked.
-Then I cleaned it very carefully and used MotoSeal on the joint (low viscosity, chemical resistant sealant). It bubbled underneath and worked its way out.
-Then I used Permatex 'spray sealant leak repair' which is supposed to wick in and seal up leaks. It still leaks.

I think the only way to do it properly is split the cases, clean it as good as possible, apply a sealant, and torque it back. I have not removed my transmission to try it. My leak is not bad enough to warrant pulling it just for that.

[Feffman]

Anaerobic gasket maker is what you want. Toyota uses it. BMW uses it on the B series engines as well.

I use it to seal up diff covers...its much easier and faster than RTV.

Loctite 574 is your friend. Spoke with Loctite just yesterday about this very subject as I'm re-assembling my manual this week.

Feff

[SaraG]

My 2006 M3 was just diagnosed with this leak…. I cannot fix it myself. Any recommendations in west Houston area for someone who thinks like y’all? Thanks!

[bigjae46]

My 2006 M3 was just diagnosed with this leak…. I cannot fix it myself. Any recommendations in west Houston area for someone who thinks like y’all? Thanks!

MC Autowerks near Synott and Bellaire. Tell Mario that Jae sent you. One of four techs in Houston that I'd let touch my car.

[SaraG]

MC Autowerks near Synott and Bellaire. Tell Mario that Jae sent you. One of four techs in Houston that I'd let touch my car.

Thank you!!

[sapote]

My 2006 M3 was just diagnosed with this leak…. I cannot fix it myself. Any recommendations in west Houston area for someone who thinks like y’all? Thanks!

How bad is the leak and at the rear cover or the bell housing joint? I would not open the case to fix it if only a little sweat as removing the rear cover is not simple.

[sapote]

The first joint at the bellhousing isn’t too bad. It’s the same for every smg to manual swap, just don’t pull it all the way. Like Gizmo said, 1/4” is fine. The pieces that fall out won’t fall out until the bell housing is about 2” out.

the other joint… no idea. Not much info out there on that one!

Can you clean the oil off the mating surface really good with only 1/4" gap and the oil continue to wick out slowly? Unless the glue can work with oily surface I think this may not seal properly.

To remove the rear cover, one needs to understand how the interlock mechanism work with those small rods and springs and how do they interact with the internal shift rods

[SaraG]

How bad is the leak and at the rear cover or the bell housing joint? I would not open the case to fix it if only a little sweat as removing the rear cover is not simple.

Transmission leaking at middle seal where front and middle portions bolt together… i have these two photos