Brake leak '94 Camry

[dreager]

I write in hopes someone else has had this issue.

I top up Brake fluid regularly but can see no leak. Assuming the cylinders were leaking I took off the drums but no leak. I took off the master cylinder, saw no blow-back but the the threads on there had a crusty white film similar to what you'd see on aluminum threads. Is this a sign the brake booster/cylinder is leaking ?

I had brake problems on my Regal which resulted in a major failure, the sheathing on the lines had caused the line to corrode internally and finally snapped. I notice the Camry has similar sheathing.....

I stopped checking at this point to see if there is any feedback on the thread corrosion.

[inafogg]

how often are you topping off & how much fluid
would'nt think brake booster has anything to do with a leak of brake fluid, maybe master cyl.

[dreager]

how often are you topping off & how much fluid

Depends how much I drive.....1/2 the res. for 150 miles. Any comment on the white stuff around master cyl. threads, is it a sign of a leaky cyl. ?

[jdmccright]

It is something to suspect...corrosion of the master cylinder threads from old brake fluid, although you would normally see it dripping from the leaking threaded connection or a stain on the parts below it. Opaque and dark green is usually a sign of old fluid.

The most typical sign of leaking brake cylinders/pistons is oily streaks on the inside sidewall of the tires. Elsewhere, usually blistered paint, rust and oily stains on the undercarriage from being blown back by the airstream...caked dust buildup, too, if you live in dry or dusty climates. If you can, top off, then wrap the various connection points with a paper towel or dry cloth and drive for a day or so. The leak will show up on the wetted cloth.

Finally, sometimes it takes a second person pressing and holding the pedal while you get underneath to watch for fluid leaks or see it drip onto the pavement...the engine can be off for this but pedal effort is alot higher since vacuum assist is absent.

Hope this helps!

[Mike Gerber]

I have heard of cases like this before. It can be your master cylinder leaking in to the brake booster. The brake booster is under a vacuum, so when fluid leaks in to it, the fluid is sucked in to the engine and burned up, like oil leaking past the valve stem seals. The only thing I can suggest is to pull the vacuum line off the brake booster and see if the inside rubber of that line appears wet from brake fluid. Maybe someone else knows of a better test for this condition.

Mike

[jdmccright]

Good idea, Mike. I wonder if you can use a vacuum pump connected to the booster vacuum hose on the booster to see if you get any fluid when you apply vacuum. Usually a large size hose, so a tubing adapter would be necessary to attach the smaller pump.

[dreager]

Based on the most helpful feedback ; the corroded thread issue and the fact a used master cylinder is only $40 I believe I'll go ahead and change it. My own hunch points that way too. Lets hope the brakeline connectors come off as easy as the Mst. Cyl. did . Bleeding the lines will be fun too I'm sure.

Thanks all

[inafogg]

just make sure you bench bleed the m/c real good,then rebleed master
when its on car.

[dreager]

Originally Posted by inafogg

just make sure you bench bleed the m/c real good,then rebleed master
when its on car.

Wow, what am I getting into? This is a first for me as far as installing a Mst. Cylinder. I'm no noob to brakes, (have done the norm, lines;calipers;pads; drums etc.) but "bench bleed" is a new one on me, so if you could loosely explain it I'll be a little more aware.

Thanks

[Brian R.]

Download the file here. This is the best reference you can get.

[inafogg]

if you have a vice to hold m/cyl steady,this is the easiest way
go buy a cheap bleed kit $5 - $10 (piece of tubing & plastic fittings to screw into m/c) with cyl held, fill master cyl about 1/2 way, push plunger in m/c to
foce air from m/c. bleed until air is out,then rebleed after installed on car(will need 2 people to do this)
they also sell air pressure kits to do this