Master Cylinder leaking at firewall

[Earnst85]

A few months ago, I had my master cylinder start leaking at the firewall (inside) and would dump the fluid into the cockpit belly pan overnight. I changed master cylinders, and ran the last few races of the year. Now, as I am building the car for this year, I put a brand new master cylinder on the car.  I bled the lines and all seemed fine. The next morning, all the fluid dumped into the cockpit bellypan just as the other MC did. Is there something that I need to do or look for that would resolve this issue?  A brand new MC should not leak like it does. I tried to troubleshoot what could be causing by removing the stem brake the brake pedal (thinking the rod was too long and was creating an always under pressure situation) but it again dumped the fluid into the cockpit without the brake pedal stem attached. When I bleed the brakes and press the brake pedal, nothing leaks or shoots out. It only does it as a slow leak overnight.

Anybody experience this before and or have any solutions for me?

[VMS Motorsports]

You need to make sure that the rod pushes straight in. If it is at any angle it can cause the MC to leak

[Earnst85]

So in other words the rod should be straight & not completely tightened ( to allow for proper allignment when pedal is pressed)?

I removed the rod and pedal last night, and it still leaked out overnight, so any other ideas besides rod?

 Does the end of the MC screw off or anything (for rebuilds)? Could it be that could be loose?

[amp racing]

common with these, we keep a spare cylinder in the garage..

[s10custom]

Shouldn't leak, replace the "O" ring in the MC.

Robert

[Legends57x]

Chad,

I've been told by various dealers that the brake master cylinders that USLC sells are of poor quality(made in China) and normally last about one season.  Leaking inside cockpit area seems to be the norm.  I would suggest purchasing a Varga master cylinder from Randy at RPM, see link below.  They are a much better quality part and they last a lot longer.

http://www.rpmracingca.com/proddetail.asp?prod=Brakes%3AM%2FC

Hope this helps! 

[Earnst85]

I've been told by various dealers that the brake master cylinders that USLC sells are of poor quality(made in China) and normally last about one season.  Leaking inside cockpit area seems to be the norm. 

This one didn't last longer than getting it out of the box. It sucks that I have to fix a brand new part.

[VMS Motorsports]

So in other words the rod should be straight & not completely tightened ( to allow for proper allignment when pedal is pressed)?

I removed the rod and pedal last night, and it still leaked out overnight, so any other ideas besides rod?

 Does the end of the MC screw off or anything (for rebuilds)? Could it be that could be loose?

Just straightening the rod after the damage was done won't fix it.
With the next one make sure that the rod is pushing in straight

[racerdad]

Are these master cylinders new or rebuilt when I was a machanic we would see new ( rebuilt ) masters leak.
Also once it leaks you have to replace it. Fluid made it past a seal it will do it again

[Earnst85]

Are these master cylinders new or rebuilt when I was a machanic we would see new ( rebuilt ) masters leak.
Also once it leaks you have to replace it. Fluid made it past a seal it will do it again

Master cylinder (leaking now) was brand new.  The one from earlier in the year, was at least a year old.

[Earnst85]

Thanks everyone for the info. I guess I will put the one I ran at the end of the season back in the car & rebuild the 2 that I have leaking.

[justfreaky]

I have not heard that particular problem on the site before. Interesting!
I do believe that a rebuild is a necessity. I agreee that the rod should push squarely on the piston, or will cause premature wear in a big hurry.
But right out of the box! That's pretty suspect.

Steve

[dirkhenry3]

I have had some bad luck with a couple of  cheap aluminum M/C I got from the local auto parts store that leaked. ever since then I have run nothing but the varga M/C and have not had one problem. The Varga are usually coated and wont corrode like other ones which is a plus.
I believe this is the Part# you are looking for which is also the VW Part#  113611015DBR. all the dune buggy and beetle guys consider this to be the best brand of M/C
Sorry im a parts guy

Dirk

[Winterracing]

Similar issue, I added fluid and bled the brakes yesterday and my master seems to be leaking where those 2 hoses hook up to it.  There just sitting in there, does anyone use any type of sealant on them?

Dan

[racerrad8]

Similar issue, I added fluid and bled the brakes yesterday and my master seems to be leaking where those 2 hoses hook up to it.  There just sitting in there, does anyone use any type of sealant on them?

Dan

No, you cannot use a sealer. Is it leaking from the hose or the grommets?

The grommets supplied in 99% of the over the counter cylinder use a low grade rubber that breaks down and leaks. I stock and sell a ton of the Genuine VW German grommets that once they are installed, after you make sure the rust has been removed, will never leak.

http://www.rpmracingca.com/proddetail.asp?prod=Brake%3AM%2FCgrommet

The also make a silicone brake hose that does not deteriorate like the black cloth hose. I have that as well.

http://www.rpmracingca.com/proddetail.asp?prod=Brakes%3ABrakeHose

Randy - RPM