89-C4: Big Leak from End of Tranny

[Larouex]

Intro: I am a relatively new 964 owner, but familiar with Porsche's and capable of doing most mechanical work.

I noticed on my ride home that I was dropping fluid in the middle of the car. I have all of the under-body plastic, so I could not see where it was coming from.

Today I jacked it up, removed the under-body and noticed that drip was coming from the end of the transmission. The fluid is red and very thick.

I am sure others have experienced this and so I looking for suggestions and things to investigate.

Larouex

[porterdog]

Front end, or back end?

[Larouex]

It is the backend transmission

[porterdog]

Not sure if by back end you mean the transmission vs. the front differential or if you mean that it's the rear of the transmission that's leaking. Assuming you mean the rear of the transmission...

To start, clean the area thoroughly so that you can tell definitively where the fluid is coming from. Since it's red, I'd put my money on trans oil though I suppose it could be motor oil or hydraulic fluid (never seen that in red personally, but it could exist.)

The obvious culprit is the input shaft seal, but it's possible it could also be from the differential actuator mounting; cleaning well and then observing the loss closely will help you figure that out, and once that's known the proper course forward will be obvious.

Check to see if either your brake fluid or engine oil are red, too.

[Larouex]

https://skydrive.live.com/?cid=AF5E81E156A64F01&id=AF5E81E156A64F01%212017#cid=AF5E81E156A64F01&id=AF5E81E156A64F01%212630

I cleaned up, removed all under body pans. I can see that the part holding the bleeder and input line seems to be leaking at the place it mats up to the tranny. I imagine this is part of the hydraulic slave cylinders?

[porterdog]

Yeah, but it's the difflock slave not the clutch slave (just to be clear).

I think that's one of the ugly ones, since PET doesn't show a gasket (see Main Group 3, Sub Group 05, Illustration 305-15, Part 20 (964 339 775 07).

Dunno what to tell you

If it was me I'd park it, drain the fluid, and pull the slave without undoing the hard line if possible. See if there's an o-ring or something.

[alexjc4]

Looks like the rubber boot that sits behind the lateral lock cylinder may be leaking. The rubber boot is n 964 301 051 01 shown in illustration 302-10 in PET.

Also you could check there is a small socket head bolt that belongs in the lowest hole on the bottom right of the join in the picture, small one like a M6. If that's missing it might leak I guess.

Attached image shows you what that rubber boot looks like with the slave cylinder removed

[Larouex]

I looked at this thread and search on removing the Longitudinal Slave valve's Key. I removed the little allen bolt holding it, but id does not slide out easy, I am not sure how to grip this thing or I am force to loosen all the bolts on the drive shaft?


C4 engine and tranny drop - Rennlist Discussion Forums

[Larouex]

I have removed the fork key finally. Now isn't the cylinder supposed to be able to come out? I assume there is nothing more holding it according to the diagrams, but it is no budging! Should I get medieval on it

[porterdog]

Yeah, a little. Soft deadblow hammer taps, perhaps some judicious heat.

[Larouex]

It was a serious PITA to get this out and once I did I can see why. The seal inside the tranny has leaked a lot and the junk was actually hardened on the actuator, what a mess. I am cleaning things up and getting ready to order the new seal.

[porterdog]

What are you using as a penetrant? Seems like everyone that's tried Kroil raves about it.

[v911king]

Hi I have a 1989 964 I also I think I have the same thing that you have. I am going to order the new seals can you tell us how you put in the new seals and how hard was it to take out the old ones?. And did you have to take out all of the trans oil to do this! thank you for all your help on this fix. Vernon.