Curse of the leaky master cylinder cover

Posted By: CJK440

Curse of the leaky master cylinder cover - 07/30/08 05:04 PM

I have a manual disk brake master on my duster. Its a reman unit and it works properly however when driving the car, fluid sloshes out of the top (I think).

Thank god I'm using DOT 5!!!

Anyway, I tried different covers and a different rubber gasket with no change.

So I pulled the master and thinking that the rim on the top was pitted I "machined" the top with sand paper on a granite block. As it cut I could see gaps where it was uneven and stopped only when I go all clean metal.

I crimped the bail wire to shut tighter.

The darn thing still leaks!!! Any tips. I don't know where to go from here.

Posted By: Y3 70 BEE

Re: Curse of the leaky master cylinder cover - 07/30/08 05:32 PM

The master is bad get a new one. Its leaking internally over filling one of the reservoirs and pushing fluid by the cap.

Posted By: Magnum

Re: Curse of the leaky master cylinder cover - 07/30/08 06:23 PM

Is there anything unique about the 1972 A body system?

I ask this because I've read a couple threads with this same concern, they were also 72.

Had a Dart years ago. Many attempts at solving the same issue. It was also a power brake 72.

Posted By: CJK440

Re: Curse of the leaky master cylinder cover - 07/30/08 06:31 PM

Quote:

The master is bad get a new one. Its leaking internally over filling one of the reservoirs and pushing fluid by the cap.

Thats an interesting thought. I suppose if I took the top off and slowly pumped the pedal, the level should increase in one and decrease in the other right??

I noticed it leaked even after trailering the car so thats why I suspected sloshing fluid.

I'll look into it some more. Not too happy about swapping it but its a small price to pay for no leaks.

The master is off a later model, 73 I think.

Posted By: Y3 70 BEE

Re: Curse of the leaky master cylinder cover - 07/30/08 06:43 PM

Try to get a new one not a reman. A few years back I had to replace the 100,000 plus mile original on my chrysler got a reman from napa and in a week or so it started leaking from the lid and the back where it bolts to the booster. Took it apart and found pits and wear marks in the bore, the core was no good they just put new seals in and ran a hone through it. Get a new bendix if available.

Posted By: F1Scamp

Re: Curse of the leaky master cylinder cover - 07/30/08 07:07 PM

We had the same thing on the AAR, put two different re-man units on. We bought a brand new one and haven't had a problem since.

Posted By: CJK440

Re: Curse of the leaky master cylinder cover - 07/31/08 12:00 PM

I popped the cover last night, that was untouched after my testdrive following the resivoir resurfacing. Both resivoirs are level.

If it was transfering fluid by way of a bad piston and overfilling one resivoir, wouldn't one be filled to the brim??

I think I am going to replace it to get a smaller bore master to help with pedal effort anyway. I'll get a new one and hopefully be done with it.

Posted By: BHuey

Re: Curse of the leaky master cylinder cover - 08/03/08 12:40 AM

Had the same problem with mine, made a new gasket out of cork, tracing the reservoir outline as a template, no more leaks.