MC Leaks from Cap

[Subzero]

I have a AL Cardone Rebuilt MC on my truck that I put on in the summer. Brake fluid keeps leaking down the side and landing on the power steering box. I clean it up and after about a week it's back. It's not much leaking but how can I stop it? My brakes work great other than that.

[stover]

Have the same problem with my MC. I will be watching this thread.

[ultraranger]

The fluid level should be at least 1/4" below the top of the MC reservoirs.

The rubber seal under the cap may need to be replaced or probably more likely, the wire bail that holds the cap on doesn't have enough force on it to tightly compress the cap down onto the seal. You can take the wire bail off and slightly tweak it, (bend it a little more where it curves), so that it'll put more downward tension on the cap.

Make sure there's no dirt, rust or debris between the seal and around the lip of the MC reservoir.

[mrtleavitt]

I had the same problem a few years ago. I bought an extra gasket from the "Help" section at Autozone and doubled them up. I have never had a problem since. Also, when you put the MC cap back on make sure the surfaces are dry.

[Subzero]

Will do, I didn't know you could buy a second MC gasket. I'll clean the surfaces up too, can I lightly sand the top surface of the MC? For some reason the outside has rusted and it is creeping in on the cover surface slightly. Probably due to it being soakedwwith fluid.

[ultraranger]

Will do, I didn't know you could buy a second MC gasket. I'll clean the surfaces up too, can I lightly sand the top surface of the MC? For some reason the outside has rusted and it is creeping in on the cover surface slightly. Probably due to it being soakedwwith fluid.

You would have to be very careful not to get any dirt or debris into the MC. Tiny bits of sand from the sandpaper circulating in the brake system would not be a good thing.

This is why I like the more modern aluminum MCs with plastic reservoirs. They're much lighter than the conventional cast iron MCs, they don't rust and you don't have to take the top off to see how much fluid is inside. This keeps added dirt and air out of the brake system.

....'95 Explorer MC in my '68 Mustang.



A '99-2004 Mustang V6 MC I installed in a '65 Mustang fastback.



A '95 Ford Windstar MC I installed in a '65 Mustang.

[Calfdemon]

We have had the same problem in CNM67's MC as well. Brand new MC, new cap, new gasket, and it still leaks out the front portion. I had not heard of doubling up the gasket, I guess that is our next step and we will see how that works out!

[mrtleavitt]

So I snapped a few pics to help everyone out. What I did was find a gasket that was identical to the original gasket that came with the master cylinder (I found it in the "Help" section at Autozone). I left the original gasket alone. I took the new gasket and cut out the insides so that just the perimeter was left. Then I just stacked the trimmed gasket on top of the original and my leaking problem was gone. Like I said earlier it's been at least 3 years now with no problems.

[Subzero]

Sounds like a plan then. I'll try that next. Thank you.
( the gasket is $10 priced at AutoZone)