I have a 79' F100 w/ a 351m and power brakes. The booster, master cylinder, steering gearbox, brake hoses, pads, drums/shoes, and rear wheel cylinders are all new. The proportional valve, and calibers are untouched and the originals. The brakes work great When I originally installed the components, I made sure to bleed each wheel to get all the air out of the fluid. This is not my first time installing new brake components on a dentside but it is the first time I have run across this problem. I usually fill the master cylinder with brake fluid up to about 3/8 to 1/2 of an inch from the top. Every now and then (not consistently) the brake fluid will ooze out of the master cylinder lid. It does not do this only once until the fluid level obtains a particular depth but it will continue to ooze out of the lid until the chamber is empty. It is only doing this in the front (small) chamber which is for the rear brakes. If I fill it back up, it does it again. It does not do it every time I drive, which is strange, but usually over a two month period. I am not braking hard and do not tow/haul any loads. Could it be a rear brake line that is stopped up? Could a wheel cylinder not be working properly? What do you think could be causing this?

Usually that means the master cyl is defective. Its not unusual to see one taking the fluid out of one compartment and put it into the other.

blacksnapon said:

Usually that means the master cyl is defective. Its not unusual to see one taking the fluid out of one compartment and put it into the other.

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It is possible it is doing this. The rear chamber stays full all the time. If the fluid from the front is making its way into the rear chamber somehow, maybe it could overflow and push the fluid out of the chamber through the lid? The lid is tight, I realize it does not always create a super tight seal. There is no pressure in the chambers, the only purpose for the lid is to keep trash out. So, it is possible that there is enough of a gap that the fluid could overflow?

the pressures generated in the mastercylinder can be more than enough to force fluid out of the cap.

I believe the master cylinder is bad. I will p/u one tomorrow. By the way, which brand do you recommend (I am buying a new one not a reman) Bendix, Raybestoes, or Cardone? I have always used Bendix because they are the more expensive but sometimes the cheaper brands can be better. What do you think?

Cardone gets my vote. Hell while you're at it, why not upgrade to a 350 MC and booster. I heard/read/talked to folks that say that upgrade alone will increase braking power up to 20%.

Bendix would be a good choice. You might even check on one from the Ford dealer. They're getting more competitive in price. At the top of the page is one of this sites sponsors (fordtruckpartsguy.com)

UTfball68 said:

Cardone gets my vote. Hell while you're at it, why not upgrade to a 350 MC and booster. I heard/read/talked to folks that say that upgrade alone will increase braking power up to 20%.

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So you think Cardone is the better of the three? I have never used their product before but if they are better, I'm all for it since they are much cheaper than the others. I'm not against the aftermarket boosters and master cylinders which I know improve upon the OE setup, I just like to keep things original. I'm hoping to restore my truck to the exact specifications that it was the day it was built by Ford. I know not many folks care about this kind of thing for 73-79 trucks because they are not worth as much as older year models, but I want to be one of the odd guys that keeps it original in every little detail down to the paint markings.

I think Cardone is great...maybe not as good as the other two...but last a good while and are quality. And as you pointed out...much cheaper.

Bendix gets my vote they make great stuff.

I've had good luck with cardone products

Thanks everyone for all the help. Maybe I'll get this thing fixed tomorrow. Hey by the way, I was looking through my folder of receipts and stumbled across a build sheet for my truck. I remember calling Ford about 2yrs. ago to get it. I found out that Ford will mail you a build sheet for any vehicle for free. I'm trying to find the 1-800 number so I can let you guys know so you can get build sheets for your trucks. I'll let you know on a new post when I find out. If anyone already knows the number post it up for the new members. Thanks again everyone.

Hey dentside...there is a fairly recent thread about obtaining the info from Ford you're talking about. Here's the link...pg 3 starting at about post 26:

http://www.fordtruckfanatics.com/forum/showthread.php?t=9239&page=3

My opinion. Get one with stainless steel sleeves.They aren't supposed to rust.

http://brakecentre.co.za/dummies_pt1.html

dentside79 said:

Thanks everyone for all the help. Maybe I'll get this thing fixed tomorrow. Hey by the way, I was looking through my folder of receipts and stumbled across a build sheet for my truck. I remember calling Ford about 2yrs. ago to get it. I found out that Ford will mail you a build sheet for any vehicle for free. I'm trying to find the 1-800 number so I can let you guys know so you can get build sheets for your trucks. I'll let you know on a new post when I find out. If anyone already knows the number post it up for the new members. Thanks again everyone.

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800-392-3673

Mil1ion said:

My opinion. Get one with stainless steel sleeves.They aren't supposed to rust.

http://brakecentre.co.za/dummies_pt1.html

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Where can you get one?