Maldini

My slave cylinder appears to be leaking, to the point where I've had to top off the reservoir after the few hundred miles I've driven so far this summer. I read a number of threads and it seems like an easy job, up until the point where it comes to bleeding the system. Hoping you guys can help answer a few questions for me.

1. I was planning to order from RockAuto, any particular brand(s) you would recommend?
2. Should I do the master cylinder while i'm at it?
3. I've read a 91 and up slave can be used, but the hard line from the master needs to be changed. Has anyone done this and can you comment on how it worked out?
4. The FSM procedure for bleeding seems odd, is there an easier way to do it?

I appreciate the help guys. Thank you.

corvette_bob

I’ve only limited experience with the clutch slave bleeding.
starting with the question of changing the clutch master, I hope you have small hands. It takes a bit of gymnastics and small hand dexterity to get the connection to the brake pedal hooked back up. I happen to be a big guy, 6’3”, so for under dash work I always remove the seat on the side I’m working on.
Now onto the slave cylinder.
It seems like all the manual transmission C4’s need the slave removed from the transmission to be bled. But because some people will ask, ONLY remove it from the transmission, but the fluid line MUST remain connected for obvious reasons.
You’ll notice the bleeder is on one end of the cylinder opposite the piston. It’s almost a must that the piston be depressed as far as you can to decrease the volume area to be bled. By reducing the bleed volume, you make it much easier to bleed and remove the air from the system. Once you’re satisfied the air is out, Make sure the master is topped off, and release the piston from its compressed state. As the piston comes back out, it will draw fluid from the master. From my experience, try to be quick about remounting the slave back to the bell housing so you don’t have to fight the fluid pressure while finagling the thing back into place. Try it out, then double check your reservoir level.
I hope I’ve helped.

Maldini

Thanks for the info, it was helpful.

I got got under the car this afternoon expecting to see signs of leakage from the slave, but found nothing. The hard line and even my master cylinder is dry with no signs of leakage.

Could my leak be from a less obvious area, potentially the master but I just can’t see it?

Thanks.

RUU

Slave could be leaking inside the bellhousing or the master may be leaking inside the car behind the insulation on firewall.

corvette_bob

My’89 had a history of the clutch master leaking. The original owner told me it ruined the electrical bulkhead connector and he had to hardwire the harnesses together as there was no cost effective alternative then.
So, I agree, check for leaks up behind the pedals, under the carpet.
The possible leak At the slave cylinder can be definitely be determined by removing the cylinder from the bell housing and visually inspecting the seal.

Maldini

I didn’t look up around the pedals yet, but I had the car in the air and I think I found evidence of the slave leaking. The drips you see in the pics (might be a bit hard to tell) were almost unnoticeable at first, but I think it’s Dot 3 fluid. My thinking is it’s leaking into the bell housing and traveling down to the lowest point where it’s dripping out. Sound reasonable or could this be something else like a rear main?

corvette_bob

Yes, it could be the rear main. Let’s hope it’s not. But that’s why I said removing the slave from its mounting
is the best way to determine if the slave is leaking.
It can be difficult to tell what’s leaking or not if the main is bad. Sure, there will be oil, but you also get the road dirt,
Dot3, and maybe even condensation from the heating and cooling of the bell housing.
Keep at it, I hope it’s an easy fix for you.

Maldini

Well at this point I am quite confidant my leak is coming from the slave. I got under the car again tonight, backed off one of the nuts and some fluid started to seep out - I didn't need to go any further once I saw this.

I did nearly break my back getting in a contorted position to look at the firewall where the master comes through - looks bone dry to me so at this point I am going to leave it alone.


I've been reading threads and I'm already dreading bleeding the system once everything is put back together. I think I'm going to try reverse bleeding the system, followed by the pumping technique, and some prayers. If anyone cares to share any other tips, I sure would welcome them.

corvette_bob

I’d say give it a try if you think you can bleed it that way. One thing I’d like to point out as a reminder, air travels upward thru the fluid. It’s easy enough to get the fluid to the slave cylinder, but the bleeder needs to be pointed up to allow the air in the system to escape when the bleeder is open.
Best of luck with it. You’re a little outside my 90-minute market, otherwise I might be there to lend a hand.
be sure to let us all know how it goes.

Maldini

Well i'd say it was a successful day. Other than it being a little awkward and a little cramped around the salve cylinder, the job went fairly smooth. I didn't end up reverse bleeding the system, I simply bench bled the slave, which I think resulted in almost no air in there, so really all I lost was a bit of fluid from the line coming down and a little as I threaded the fitting onto the new slave. I topped off the fluid and had my pedal back in less than 40 pumps i'd say. I continued to do it more just to ensure no air was coming out and even recorded with my iPhone, so I think I'm good. I put 25 or so trouble free miles on the car afterwards as well.

Here are a couple pics of the old slave and of course the new one. Without a doubt it was leaking...

I appreciate the help everyone!

corvette_bob

Congrats. I wouldn’t have thought of doing it that way, but if it works, it works!