QuestionThanks for your advice,i checked all the lines and they look dry, the only thing that i didnt check were the drum brake cylinders that actuate the brake shoes.The master cylinder conver is a steel unit and the rubber seal/gasket looks fine and it only oozes when i apply the brakes. I also think that its a venting problem but have no clue as to where the port is or if even it can be cleaned replaced or just adjusted.You mentioned that if thats the problem I have to replace the the entire master cylinder.Is that the only cure?
Thanks again
tom s.-------------------------
Followup To
Question -
Hi;
I have a question regarding my '76 Chevy Nova with power brakes. Recently i noticed that my power brake reservoir ,the first towards the front of car tub was empty.I added brake fluid and now all i have to do is bleed the system,but where did the fluid go in the first place? Pumping the brake pedal i noticed that fluid is oozing from underneath the master cylinder cover,the steel cover not the newer plastic cover.The rubber gasket seems o.k.,i even put shims underneath the wire/clip and the cover for more downward pressure but it still oozes when i apply the brakes.What is the problem?
Thank you
Tom s.
Answer -
The big question here is: why was the front section empty? On your car, I believe the front section is the one which operates the rear wheel brakes (you can follow the fluid line that comes out of the side of the master cylinder to make sure that it is the one that heads back along the driver's side frame rail to the rear). If this is so, you need to inspect the whole line and the innards of the rear wheel brakes to see if there is any leakage of fluid back there, and fix that problem.
Fluid leakage from the reservior cover (if that is what you are describing, I'm not exactly certain after reading your question, because of your mention of metal and plastic covers) is most likely because of overfilling the reservior, if the gasket and cover is intact with no cracks. It is possible that the vent or check valves are not working properly, causing pressure to build up under the lid, in which case the cure is to install a rebuilt master cylinder, but I think you need to find out why the front reservoir went dry - that's a serious problem for your safety.
With any power brake car, there is a failure that sometimes occurs where the vacuum hose from the engine can actually suction fluid out of the fluid reservoir - but when I've seen this problem it shows up in the reservoir section that is closest to the firewall, not the front one. However, to eliminate this possibility, remove the vacuum hose where it comes into the side of the brake booster, look to see if the inside of the hose is moist and just sniff for the odor of brake fluid. If you can smell it, that is part of your problem.
I hope this is of some help to you,
Dick
AnswerI think you should take the lid off the reservior (the metal one anyway) and see if you can remove the rubber liner from the underside of the cap without damaging it. If you can, see if there is a vent hole in the lid that is blocked with some crud. Usually, there is such a vent in each cap - and if that becomes blocked, any pressure that builds up in the reservior will find a way to seep out around the gasket.
But I'm still concerned here, because I cannot see how that would empty the reservoir completely. I think you should pop off the two rear drums and take a look in there, just to be safe. Of course if the rear brake cylinders are leaking, you should see seepage around the rubber end caps on each cylinder, and maybe even fluid draining down the backing plate. If everything seems dry back there, then I don't know what else to suggest. A rebuilt master cylinder (you don't have to replace the booster if it passed the sniff test of the hose), will only cost you about $30 at Auto-Zone, and I think it would be money well spent for peace of mind. I admit this is a bit of a shot in the dark, but I cannot think of anything else to tell you.
Good Luck, and let me know what you find out.
Dick
