Brake Fluid Reservoir Leak

[alanc]

Has anyone ever replaced that rubber washer at the bottom of the brake fluid reservoir? What all's involved?

Will I have to bleed the brakes afterwards?

Mine's a gray market 500SL ('83). I figure it's about the same as the 380.

Alan

[sokoloff]

Brakes are supposed to be bled once a year anyway. Just do it when you bleed the brakes. However, I don't think you have to. On my 240D the reservoir just pulled off. Replaced the rubber grommet and reinstalled the reservoir. I bled mine at the time.

Len

[alanc]

Thanks Len.

[alanc]

It turns out you don't need to bleed air from the brakes. The reservior just pops off out of two holes feeding into the master cylinder. The holes are upright so the fluid just pools--no air gets in as long as you leave the holes full. The brake pedal didn't soften up at all after I was done.

Interesting footnote. What we're calling a reservior is really called an overflow in the (spectacularly unhelpful) MB manual. It has all kinds of interconnecting chambers that I think must cycle the brake fluid as it jostles around in there. I think it must be designed to separate out some of the foreign gunk. There's a little appendix-looking thing that sticks out, and looks like a rubber overflow hose is supposed to be attached to it, but it has no hole in the end. Sludge just collects inside it, and mine's nearly filled with it.

There was a lot of light sludge on the walls, too. What I thought was discoloration in the plastic was a thin coating of sludge. The gunk mostly came loose when I shook it up with fluid in it, you but can't really get it all out because you can't get to all the chambers. My reservior actually turned out to be the color of the washer fluid reservior--white transluscent. If your's looks dingy and semi opaque, I imagine it's coated with sludge. I think I'm going to just put in a new reservior. My version (there are several--mine's triangular shaped) only runs about $50.

I'm going to bleed the brakes this weekend just to be sure some more sludge didn't break loose.

By the way, I had a lot of trouble getting the reservior to seat just right in the master cylinder with the new seals on it. Though it isn't leaking, I never did get it to seat perfectly flush. Has anyone got any suggestions?

Alan