tires and wheels losing brake fluid?

[andrey]

The "brake failure" light came on a week ago and I topped up the brake fluid (it was indeed low). This morning the light was on again and, again, the fluid level was about where the clutch line exits. Ugh.

I don't see any obvious leaks (but I have yet to pull all the wheels off and really check), should I suspect the master cylinder (rear seal, leaking into brake booster) or are there other good areas to check?

Thanks!

[Chamonix72]

Check the pedal box too. Maybe a leaking clutch master?

[mcaden]

Good starting places - check for a leaky master or slave cylinder... look on the driver's side frame rail for fluid or the pedal box (carpet around pedal box). As needed, look for brake fluid spots under car in the am to help direct you. Fix asap and good luck.

[chat66]

Had a similiar issue, the fluid in my 76' was blowing by into to my booster. The booster should be dry and clean, not full of brake fluid. Changed my master cylinder, problem corrected.

Note: if you have a stuck brake piston or two that could also create blow back into the booster.

[eurotrash]

You're brake master can leak into the booster and then your vacuum line can pull fluid into the fourth cylinder intake runner. So if you have noticed any unusual smoke at tail pipe...

[nbristow01]

The "brake failure" light came on a week ago and I topped up the brake fluid (it was indeed low). This morning the light was on again and, again, the fluid level was about where the clutch line exits. Ugh.

I don't see any obvious leaks (but I have yet to pull all the wheels off and really check), should I suspect the master cylinder (rear seal, leaking into brake booster) or are there other good areas to check?

Thanks!

Another easy way to check, if visual inspections show nothing, is see if it reservoir continues to get lower after it passes the clutch hose nozzle. If it does the leak will be brake system related. If it just drops down to the level of the clutch tube nozzle and stays there then it will be clutch system related

[andrey]

Thanks for the great suggestions! I'll let you know what I find tonight.

[bimmerboi]

yeah my level is dropping too but i can see a leak coming from my master cylinder. i guess its a really common problem

[nbristow01]

yeah my level is dropping too but i can see a leak coming from my master cylinder. i guess its a really common problem

Yep, my sons just started leaking at the brake MC. His rubber grommets are toast so his leaks at that point. I ordered a set from BLUNT, they are about 4 bucks each.

[vinceinIL]

Yeah, it could also be a leak at one of the rear wheel cylinders, if someone else hasn't already mentioned it. I ran into this problem while driving Chet's white tii across the country a decade ago.

vince

[jgerock]

The vacuum booster should have been re-named the "auxiliary fluid reservoir" or the "big ol' drum of fluid"

This picture is from the '69

No leaks - but the booster was so full it started leaking as soon as I loosened the (2) master cylinder nuts.

[Napes]

When the brake fluid in the reservoir started dropping as you've described, and I could find no trace of a leak anywhere, I pulled the MC and used a turkey baster to get a large soup can amount of fluid out of the booster.

Not the most uncommon malady on our cars. Just wish reconnecting the brake lines on a new MC wasn't such a pain.

Bob Napier

[bimmerboi]

yeah my level is dropping too but i can see a leak coming from my master cylinder. i guess its a really common problem

[andrey]

I still haven't gotten to fully inspect it (hopefully this weekend) but it does seem to be clutch rather than brake related (plus all my brake parts are relatively new, aside from the master cylinder) due to the fluid never dropping lower than the clutch line. Nothing on the carpet though, so maybe it's the slave cylinder. I'll inspect both before assuming it's the MC and checking for brake fluid in the booster, our Opel had that problem just a week ago.

[roadhog0]

Clutch master. Mine was original and worked PERFECT. It had been dribbling a little since I bought it and finally just started to piss not to long ago so I broke down and replace it. My slave was leaking too so I replace that a year or two ago now. Either or replace em both, it's just worth it.