Leaky brake fluid resevoir

[DimitriT]

This is an 82 GS550L which has the rectangular front resevoir. I noticed that it leaks fluid.

Is it a simple replacement of the gasket (with the expanding rubber bladder) or should I rebuild the master cylinder.

Is it normal for some fluid to squirt our from the master (back into the resevoir) when I squeeze the lever?

The front brake seems to work ok. Probably needs a new hose.

[SqDancerLynn1]

You may need a new cover They warp sometime & then will not seal.
A bubble when moving the lever is normal

[8trackmind]

Re: Leaky brake fluid resevoir

This is an 82 GS550L which has the rectangular front resevoir. I noticed that it leaks fluid.

Is it a simple replacement of the gasket (with the expanding rubber bladder) or should I rebuild the master cylinder.

Is it normal for some fluid to squirt our from the master (back into the resevoir) when I squeeze the lever?

The front brake seems to work ok. Probably needs a new hose.

Hey, I have a brand new rectangular resevoir with the cap, rubber and o-ring. I haven't had it a month. Check your PM.
Fwiw, I changed out the master cyl to the older round type 'cause the piston was leaking on mine. I thought it was the resevoir too but...Nope.

[DimitriT]

So I made a gasket for it out of some cork/rubber material. I cut it out using an x-acto knife and the results were pretty good. I also went back and read some old posts on bleeding the brakes. This time I tried compressing the caliper using an big C-clamp. Sure enough a bunch of bubbly brake fluid came out when I released the bleed nozzle. I bled out about a resevior's full of fluid and then release the clamp and pumped the master cylinder until I had pressure back through the system. The results are good: less drag on the wheel and the springiness in the lever is gone. Action now is smoother with a little more travel in the lever. The resevior leak is also fixed.

BTW, I was worried the brake fluid would eat this gasket material. So I experimented by cutting a piece and putting it in a small pyrex dish with some fluid. I then let it sit in a warm place for a couple of nights. No visible change in either the fluid or the material but I plan on opening up the resevior in a few months to check on it. This is the same stuff I used to fix my leaky gas cap.

[Jethro]

Just make sure the cork is cut really clean. It doesn't take much to clog the tiny return feed into the resevoir.