The Stovebolt Site Forums The Parking Lot Big Bolts Trouble with brake booster

I'm having an awful time with the brakes on my 1953 model 6400. The whole system is new. Cylinders, shoes, master cylinder, booster, lines, etc. I can not get them to stay up. I bleed them, and will have a good firm pedal, with almost no play. I drive it a little and the pedal starts to go down, and before long, I need to do it all over again.

I think the problem must be in the booster. I haven't had any experience with one in the past, but have been told that I should be able to hear it working in the cab through the vent in the cab corner. I don't hear anything at all. I'm about to disconnect the thing, and just go with totally manual brakes. I don't plan to haul anything very heavy, and plain brakes should be just fine, but I really don't want to do that.

Has anyone else had a problem like this, or does anyone have any suggestions, other than buying another new booster, which I refuse to do.

Thanks, Allen

Hy Bakerallen, are you loosing fluid? Does your pedal feel firm when you have a good one? You said your system was rebuilt, did that include the booster? If you have been losing fluid with no visible leaks, remove the plug from the booster can and see if it's in there. If you give us more info we should be able to help.

I don't seem to be losing much fluid. I have a very small leak at one of the connections, but not much. After I go over the system, I will have a good firm pedal, but it will gradually go away. I didn't rebuild the booster myself, but I did buy a new one from NAPA. I feel sure it was rebuilt, because I don't imagine anyone is making new ones any longer. As I said earlier, I don't think the booster is working, because I can't hear it doing anything, and while it doesn't take a lot of pressure to work the brakes when they are up, it does seem to me they should be a little lighter if the booster was doing its job.

I have never taken one of these apart, but I don't imagine it is too complicated. Have you had any experience rebuilding one? I don't remember seeing a plug on the booster, but will look for one, the next time I am under the truck. Thanks Allen

Hy Bakerallen, a simple test to see if the booster is working is, get in the truck and pump the brake pedal, now hold the pedal down, now start the engine, the pedal should go closer to the floor when you start the engine with your foot on the pedal, hope that helps.

3B. Thanks for the tip. I'll give it a try and let you know. Allen

I've had these same problems. I think it is your "small leak". Mine is leaking around the fittings as well and before you know it- no pedal, no brakes. All of the fittings are new, is that the problem here?