Sab

I recently changed the brake fluid on the '82. I did it with the powerbleeder and all seemed fine. I left the system pressurized over night, since I didn't finished finish bleeding the clutch. It was still pressurized in the morning. I finished up and seemingly no leaks.

Now two weeks later a puddle on the floor.

I washed it all down and refilled and it is wet somewhere under the reservoir and around the upper bolt to the brake booster. the blue / grey hose is dry. It leaks quite a bit.

What could be amiss here?

nosnow

sounds like you need the little rubber o-rings that the reservoir sits in and seals it to the master cylinder.

Sab

I just hopeit's not the master cylinder.
OK, how do I check whreit is coming from?

Sab

OK, I think I see what you mean. The rear O ring is wet, so that'swhere it is coming from.
How does this come apart?

nosnow

You may need a mirror but simply look under the res/top of master cylinder, if the little black rings are wet that is most likely the leak. Leaving the res pressurized probably weakend the already aged seals and the new fluid probably finished the job. Replacing them is easy and cheap but a PIA as you have to reblead everything.

http://www.mailordercentral.com/928i...355%20922%2000

nosnow

You have to pull the reservoir off, straight up. Pull and rock carefully, you don't want to break it. Then the two o-rings come out, put the new o-rings in and gently push the reservoirback in. The trick is to not break the reservoir, especially with the new seals as it won't want to go back.

Mrmerlin

SAB if the master is older than 8 years instead of just replacing the resivour seals you might consider replacing the whole matser cylinder.
My guess is that the resivour seals are probably OK but old, and the master cylinder has gotten wet and then rust formed aroung the seals and is is now bad enough to cause a leak, you will see this after removing the master cyilinder resivour, dont leave the resivour pressurised overnight its not meant for this.
To clean out the resivour drain the fluid, spray the inside and outside with brake cleaner, rdrain this out then spray in some simple green shake vigorously do this a few times then rinse the resivour with hot water, drain this out then fill the resivour with isopropil alcohol drain do this a few time then using a hair drier dry the resivour this will make it look like new. Also check the resivour for cracks near the nipples that fit into the master

jpitman2

The rubber grommets are common to MB and other german cars that use ATE brakes, should be easy to find and cheap. I changed mine in the same circumstances without needing re-bleeding, as air cant get in from the top into the cylinder.
jp 83 Euro S AT 51k

Lizard928

or to get the resevior off just hook up your power bleeder sans fluid and pump it up, at around 15-20 PSI I am told that it will simply pop right off.

JP Rodkey

I noticed this is a five speed. Before going in too deep, you might want to inspect the blue clutch hose on the bottom of the reservoir. Last time I used the power bleed, only a little reservoir pressure caused brake fluid to seep from the hose where it fits onto the reservoir.

Sab

no, it's definitely not the blue hose. The rear washer under the reservoir is soaked and the blue hose is bone dry. I ordered the two rubber washers, let's see.

marton

Hopefully as the seals are old & one is leaking then this will work.

On mine I had to jam a big lever between the M/C and the reservoir and push very hard; I was convinced it would break.
Same process in reverse to fit it.

Just a thought but I suppose the reservoir has not popped up slightly one side to cause the leak?

Marton

Sab

Just replaced the seals, the master does not look too nice. Some rust has formed around the seals. It is airtight for now with the new seals, but I will replace the master soon.
As always, thanks for all the great help and suggestions.

Rob Edwards

My turn-

I pulled the GT out of storage for the summer, it's been sitting for a couple of months. Got the low brake fluid warning, the fluid was about 1/2" from the bottom of the reservoir. I had the brake M/C out back in 2009 (I remembe cleaning the res but can't recall if I R&R'ed the grommets) but this leak has cropped up during the last couple of months in storage. Hopefully it's just the grommets but have an MC in reserve just in case.

jheis

I came out to find a 1' puddle of brake fluid under my '89 a couple of months ago & found that it was wet between the reservoir & the M/C. Sprayed everything off with brakeclean, refilled the reservoir and ordered the grommets.

Never got around to replacing the grommets, but it hasn't leaked a drop since.... No idea why it would leak once & then stop.

I'll second the caution to be gentle when removing the reservoir - they are quite spendy....

James