Mercury Cougar Owners banner

Brake fluid leaking from cap?!!!

7.2K views 9 replies 9 participants last post by  texrep  
#1 · (Edited)
New master cylinder, brake shoes, drums, power booster.
I was going over the vehicle one last time before the maiden voyage to the local inspection station; I checked the brake fluid level and noticed the front reservoir very low, this was puzzling because 3 weeks ago it was full.
I went to each wheel checking the slave units for leakage, all this turned out o.k. I checked the brake lines from front to back for leaks, no leaks. I could not figure out where the fluid was going, I should also mention for the past 3 weeks I had been fighting what I thought was leakage from the power steering control valve, I could never find where it was leaking from.
I also noticed that the master cylinder was wet this I thought maybe one of the lines, all lines were tight. I filled up the reservoir, with the engine off, and every thing snapped back in place I started pumping the brake pedal I than checked the master cylinder, it was wet again. I noticed than that the fluid was seeping out from underneath the brake cap. No the reservoir was not filled completely to the top so it was not the cap pushing out excess fluid. What seems to be happening is the brake being depressed is creating enough force to shoot the fluid out from under neither the cap.

I don’t know if I’ve explained this scenario well enough for anyone to get a good idea of what is going on but if you have just a hint of what might be going on please let me know.

The brighter side of this is the power steering leak; I’m now guessing has been the brake fluid dripping from the master cylinder to the control valve.
 
#3 ·
That's a weird one but the good news is that you just need to get another master cylinder. What brand was it? I have had good luck with Wagner brake parts purchased from Pep Boys. The master cylinders I get are the new ones, around $50. I looked at a rebuilt one from Pep Boys ($18) one time and it was not like the original in shape so I passed on it.
 
#5 ·
I strongly suggest getting brand new master cyl's. I recently tried a "off brand" instead of the usual Bendix. The casting was very poor, machining was incomplete. I spent a few extra hours trying to make it work. Then it leaked from the cap. Seems the steel of the clamp/rod is cheap and "gives up" it's spring after a few topping off's. I finally went and got a new Bendix, no problems. Another reason I am very brand loyal, only takes one time to prove a point.
 
#6 ·
Make sure the rubber seal under the master cylinder cap is intact and in good condition. Also make sure the wire bail holds the cover on tightly.
 
#7 ·
hmmm i have the same problem too.... except i dont think the master cylinder is really dripping ( or i just havent noticed it ). but every so often the front sump in the master is low and i have to refill it. matter of fact it went damn near all the way down before and well... drove 10 miles home with only rear brakes lol. i was never sure what it was but now that makes sense... too poor for a new master though so ill just keep checking it i guess.
 
#8 · (Edited)
bowl going dry is from a leak usually at rear cylinders but possibly a pin hole in a brake line running near differential. One emergency braking can pop the line open rendering rear brakes void. I recommend you address your brake problems ASAP for the safety of others if not yourself. Even if the cap is leaking running out of brake fluid can be disastrous
 
#10 ·
Orrrrrrr... Get a good one as Royce said... my .02


Don