We bought a universal master-cylender and booster assebly from a hot rod outfit for our '49 Stude. We ran all new brake lines and put brake fluid in and nothing happens. When we're bleeding it, no fluid moves. The bubble just goes back and forth. We then tried every trick in the book; pressure bleeding, vacum bleeding, bleeding from the discs and drumbs. Nothing seems to work. My dad has done a fair amount of hot rodding and decided that there must not be a ckeck valve in it. We take it apart, and sure enough, no check valve. Then we decide to compare it to a stocker. Open that one up and there is no check valve. The only difference is there is tiny holes drilled through the fat end of the plunger, on the other side is a disk that seats up next to the holes. So we think, ahah, this must be the check valve. We then go to an auto part store and order a rebuild kit for it, the kit doesnt have the hole/disk type valve but one through the brake lines, (that wont fit our master cylender). So you ask why not just get a new master cylinder? well the universal one has ports on both sides. We ran the lines off the left side, a stock cylinder only has ports on the right. So we dont want to spend another $325 on a new one. After all that, does anyone have any suggestions? We're getting real flustered on this end. Thanx for your help
4 Jaw Chuck
08-11-2002 09:58 AM
No fluid at all flows through the bleeders? Could be the inter-circuit seal that keeps the front and rear sytems seperate, if that is bad you will not get any pressure to the bleeder but will work normally when the bleeders are shut. The seal is in the master cyl and is the middle seal with springs on either side. I would check out the casting too, an open pore in the bore would bleed off pressure too.
We kind of need a better explanation of the problem to help you diagnose further.
08-11-2002 11:09 AM
ok, Heres more on the problem. The pedal is squishy and puts up some resistance, (probably just the springs) but still goes strait too the floor.
We decided to see how much pressure is coming out of it. So we took the line off the porportioning valve (the line coming from the mastery cyl. not the one coming out of the valve). The only pressure we got, we could stop with our finger. Some fluid comes out of the bleeders,(a drop) then nothing happens. With all the other bleeding we did, we might have even bled all the air out of the system. But there just isnt enough fluid moving to engage any of the brakes. There isnt any leaks that we know of, so... one thing that puzzles us is that its dual cylinder-master. so we thought that, even if one of the circuits isnt working, the other would. I thought that was the whole idea behind a dual cylinder design? i checked the castings, and they look fine. its like everything is right, it just doesnt work...
4 Jaw Chuck
08-11-2002 01:47 PM
Use a vacuum pump at each bleeder to draw fluid into the system, you must have someone hold the brake pedal down or fluid will now flow while doing this. Once the system is full try it and see how it works, sounds like you have one mother of an airlock. Suction is the only way to get the system primed.
08-11-2002 05:58 PM
I'm by no means an authority on this but I had a simular problem. Mine ended up being the brake pedal wasn't returning all the way which was not allowing the plunger to return and do its job.
08-12-2002 10:20 AM
steve here one thing you need to do is like the other guy said ck the plunger travel the other thing you need to do is bench bleed the master cylinder need to take the brake lines off the master cyl. and put some rubber hoses from the master cyl. and put them back into the top of the resovor submerged in the fluid and then pump your pedal slow till all the air is out if you do not get any fluid out then something is wrong with your master cyl. or the push rod is to short hope this helps steve.
08-12-2002 01:47 PM
I had the same thing happen with a master cylinder and it turned out to be the same problem that 53 Vicky described, the plunger was not returning all the way in the bore of the cylinder. Turned out to be a slight burr on the aluminum plunger body which after sanding down cured the problem. Hope this can be of some help to you.
08-16-2002 11:58 AM
i'm w/steve as mine came with directions to "bench bleed" first or it wouldnt' work.(as per his directions)but you do it until bubbles quit coming out of the bottom of each reservoir. my mech. friend next door also is telling me (although my brakes seem to be working fine) that i still need to have someone gently and slowly put pressure on the brake pedel and crack each line at the master cylinder till a little drop of brake fluid comes out. claims air will migrate to the top of the line there.