So I was backing out of my parking spot this morning and the brake light was still on, of course I knew I must be low on brake fluid. Well after class i popped the hood I am 1/2 low in the resevoir, so i started looking for brake fluid, there seemed to be a puddle on the ground but wasn't sure if it was mine or someone elses car leaking. So I think I found some fluid where the master cylinder goes into the brake booster. Is there a gasket b/t the two or am I needing a replacement master cylinder? The brakes by the way work good as ever, and the car only has 82k original miles on 88 one owner vert. I appreciate all the help i can get.

 

There is no fluid connection between the master cylinder and the booster. It's simply a mechanical connection--no fluid. Of course, there are fittings for the brake lines in the master cylinder and maybe that's where the fluid is leaking? Position the car over a "clean" area and put a strong, steady pressure on the brake pedal for a few minutes. If you have a leak, the pedal will gradually drop and you will find a puddle of brake fluid on the "clean" area where it is leaking from.

How long has it been since you last checked fluid level in the master cylinder? If it has been a really long time, you may not have a leak. As the brake pads wear more fluid is required in the lines and calipers, and that results in a drop in fluid level in the master cylinder over time.

 

its been a while, but it seems like a lot of fluid being used, about half the resevior, but thats possible. the brake pedal is as solid as a rock, doesn't go down at all. Oh yeah should i have tested it with the engine running or not? i did this with the engine off.

 

it could be that the rubber cups inside the master cyclinder are going out, that would explain the fluid, it's cheap insurance to rebuild the cyclinder or for some more $$, have it replaced

 

Never mind. Comment deleted by author. Not sure how to delete my reply.??

 

Doesn't really matter. Like I said, if you sit in the car and put heavy pressure on the pedal for a minute or so and it doesn't go down, even slightly, and you don't see brake fluid under the car, you don't have a leak. Refill the MC reservoir and keep a check on it.

 

what do you mean comment deleted?

 

someone help lol....stop arguing and help me dammit

 

try locating the leak by putting cardboard under your engine bay, rear end, and under the master cyclinder, get back in car and pump brakes for 5 minutes and then check the cardboard for any leaks.

 

I mean I made a comment and then decided it was wrong. So I deleted the comment.

 

When Master Cylenders go bad, they usually leak from the rear seal, that is on the side of the MC that fits into the brake booster. Mine just failed last week with the same problem

A ramanufactured one is about $100

 

Nobody is arguing. What more help do you want? Do what has been suggested and find the leak, if there is a leak. Then fix it.

And BTW, this is a volunteer forum, so don't demand help or you will get nothing.

 

Actually, I've found that to be not true (in all cases). My master cylinder leaked when it was cold, but DID NOT leak under pressure. Based on how it proceeded to semi-fail (no brakes with slow pedal application, brakes with fast pedal application), I suspect the seals weren't quite against the wall, but brake system pressure would force them out and make them seal properly.

Regardless, the puddle under the car is most likely yours, and you should replace the master cylinder soon (or have it done). I was able to replace mine for $50 or so (O'Rileys reman part).

-=Russ=-

 

okay, do you guys think the reman a1 cardone is good enough, or should i get the brand new one? Is the performance of these aftermarket master cylinders similiar to the factory OEM part? Anyone have problems with transfering the resevoir to the new mc have leaks and other problems?

 

you can transfer the res. to the new MC but be careful when trying to get it off. You can go with a new MC if you have the money to, but just a rebuild kit will fix your problem, if thats where it's leaking from.

 

i was just gonna do a rebuild...but no warranty if it messes up again... also most of the rebuild kits i've found cost as much or more than a reman or new aftermarket mc...unless i got mazdatrix to get it....let me know what you found...

 

Mine was leaking from the rubber grommets the reservoir sets in. Bought them from mazda for 6 bucks. pulled the reservoir(very carefully by working it back and forth and pulling hard) and replaced them. Worked like a charm.