C4 leak -Servo cover?

[Austringer1]

1st post, thanks in advance for any help. I'm just getting my 77 going. On my way back from a test drive, I noticed it was leaking transmission fluid. I tightened up a couple of bolts, but it still leaks. Can you tell me if this is the reverse servo? If it is, do you think the servo cover loosened and maybe the o ring got pushed out and pinched? In the photo it looks like some rubber or sealant oozing out.
Since I am not a mechanic, maybe I'm completely wrong. can you give me some ideas?

 

[DJs74]

Welcome to CB.com!

This site has some real geniuses on C4s and will tell you better but in the meantime, here are a few things to think about.

First, you might check to see if there is any fluid above the servo cover just to make sure it is actually the cover leaking - the fluid might be coming from somewhere else and running down to the cover making it look like its the cover. There is a vent on top of the transmission so maybe a little fluid came out of it and ran down?

The servo cover has a flat gasket to seal it but there is also a piston behind the cover which also has a seal on it. If you take the cover off, I think the piston will also come out because there is a coil spring behind it. Your bands have metal bracket / threaded stud looking hardware attached to them for adjustment purposes which are attached to the piston so if the piston comes out, the band hardware will also become loose and try fall out - kind of a chain reaction by nature. So, what might seem like a simple cover gasket change might get really involved really quick, just proceed with caution.
As mentioned, others on this site are C4 gurus and can probably tell you the best method to check / fix your problem and suggest the best way to handle all the components behind the cover.

I've never had servo covers / servos apart but I have had a lot of valve bodies out and can see the bands, band hardware ends, etc. that connect to the servo piston. It might be that you'd need to remove your transmission pan and valve body to get the necessary access to your servo assembly - but you might hold tight on tearing into it until the experts weigh in.

Good luck & welcome to CB.com


DJs74

 

[timfoster]

I just replaced the rubber seal on my C4 reverse servo because it was leaking. You can try tightening the bolts on the servo cover to see if the leak stops. On my C4 I was able to remove the cover to replace the flat rubber seal. The piston and spring can be removed by pulling the piston out without having to remove the pan or valve body. You do not need to remove the piston to replace the gasket.

 

[Austringer1]

thanks for the information. Sure enough, the quad ring got pinched when I tightened the bolts. actually an easy fix.

 

[DirtDonk]

Yeah, that's a dandy leak maker right there!

And welcome to your first posts. Not that you haven't been here awhile, so any welcome is relative. But glad to have you on board.
Let us know how your EB turns out. And since you're a contributor too (thanks by the way!) post up some shots of your rig.
Even if it's not done yet, so we can check it out.

Thanks

Paul

 

[Gwunited2]

thanks for the information. Sure enough, the quad ring got pinched when I tightened the bolts. actually an easy fix.

When I am looking for this part, what is it called? Servo Gasket, Quad Ring Gasket? Is it easy to find at NAPA?

Thanks

 

[Austringer1]

I called it the quad ring that goes on the rear servo cover. I didn't go to a parts store, I went to an automatic transmission shop. I didn't have to tell them what it was, I took the cover in and they knew what it was.

 

[Viperwolf1]

It's like a square cut o-ring. You probably can't find it by itself in a parts store unless you buy the overhaul kit. You can buy it separately here: http://www.bulkpart.com/2/product/26364.html