I'm pretty sure they need them. They are designed to hold preesure and to keep the shoes close to the drums so they don't have to move very far. Thus helping maintain a high and hard pedal.
that is probably my bike pump back bleeding method. I know it sounds crazy. But back bleeding is a factory approved method for bleeding cars with m/c lower than the wheel cylinders. I've got some Nash metropolitan service information from the fifties that outlines this method. I asked one of the old timers at my dealership at the time about it and one of them recommend the bike pump instead of the oil can. I've even used it on a 1983 mercedes to back bleed the clutch slave and m/c which is just about the worlds hardest hydraulic system to bleed.
Well thank you for the advice everyone. Looks like i have some work to do. I'm going to start with pulling the MC and bench bleeding it(on a work bench lol) Can anyone give me more detail as to what i should look for as far as inspecting other parts of the MC that could have gone bad by over stroking the rod? Thanks! Chris
It's just the seal inside that gets torn up. what happens when you over stroke the master is that the seal goes from the nice machined portion of the cylinder to the rough as cast portion of the cylinder and tears the seal. If you have it apart I would also make sure that the bore isn't pitted too.
I had a car once I could never get all air bled and come to find out a rear wheel cylinder seal was leaking inside the rubber cup and eveytime I would try to bleed them it had air in it. Finally pulled the rubber cup off one day and found it had a little brake fluid in it. I guess it was actually leaking a small amount when the brakes were applied inside the rubber cup and then ****ing some of the fluid along with air back in the system. Everything was new on the system. Replaced one wheel cylinder and they finally bled. Lesson learned for me.
you could try blocking the fittings coming out of your master to see if it is the problem. should get hard as a rock
I took the master out lastnight and the rubber on the piston was bad. Everything else looks ok so I'm gonna get a rebuild kit. How can I find out for sure if my MC has a rpv valve in it? Thanks everyone for the help! Chris
on the old ones, it's usually a little part that goes next to the outlet port, like J in this picture
It will come in the rebuilt kit. Just replace things in the same order as they were removed from the cylinder bore. Most rebuild kits don't have exploded views so pay attention to how it comes apart. Check the bore for gouges.
First thing to check is the brake shoe adjustment. Next the Master. Remove the brake line from it, and put an inverted flair plug in the master where you removed the line. If the master is ok, it should be high and hard. next, reattach the brake line, and bleed the brakes.Clamp all the rubber brake hoses with clamps (be careful not to cut them) try the brake pedal again. If it is still hard, your problem is in one or more of the wheels. Remove the clamps one at a time and check the pedal each time. the brake pedal will get softer as you do because the the wheel cylinders are working. re-clamp the hose and move to another hose. Continue until you find the defective or air bound brake. Money, Horspower, Brakes. I never have enough.
When a system has been purged of fluid for maintenance/new master/new wheel cylinder/ etc. Bench bleed MC before installing it. Then I position a fluid bottle at each wheel with plastic tube snugged over the bleed port and other end submerged in fluid in bottle. As the process progresses, the fluid level in the bottles increase making it necessary to return it to the master cyl, also saves the fluid that has been bled out, and there is never any chance of any air entering the system. All air is eventually eliminated. Those four 'bleeding tools" are on the shelf for next time. It's Idiot-proof
Im gonna try and break down the whole process for you, as simply as I possibly can I hope it helps. You can bleed the MC without pulling it . Simply put bleeder screws or cut hard lines in the outlet/s on the master. Connect clear rubber hoses to them . Fill the master and put the other end of the hose/s into the master .. Make sure the ends are fully submerged. hold the hose/s so they dont pop out, then have someone slowly pump the brakes untill no more air comes out. Once that is done,reconnect the lines and move on to the brakes. First off make sure you never let the master run dry, and dont forget to Make sure the shoes are adjusted all the way out. Start with the furthest brake from the master. What I allways do is put a clear hose on the bleeder (Make sure it fits tight) and loop it up above the bleeder itself. It makes it easier to see the air come out, it lessens the chance of air being ****ed back in, and you can aim the end into a drain pan for less mess. If the system is dry, I will plug the bleeder with my finger and have someone slowly pump until fluid starts to come out. Then with the pedal depressed to the floor tighten the bleeder. Next I repeat this process on the other three. Moving in succession from furthest to closest. Once all the lines are full of fluid I go back to the furthest brake. This time around I have my ***istant pump the brakes 3-4 times then hold the pedal to the floor. Open the bleeder, let it squirt, then tighten it again. Let the pedal up, then repeat. Continue untill no more air comes out. Then move on to the next furthest away, and repeat.. I hope this helps, if you follow allthese steps to the letter you should have decent brake pressure by the end. Sometimes going back around and bleeding a second time helps as well, and with power ***ist brakes bleeding with the engine running is sometimes necessary. When all that is done dont forget to adjust the shoes back out I hope you find that helpfull
I drove a '54 Pontiac every day for two years when I was in High School. If you have fluid shooting out the hole in the cap you need to rebuild that master cylinder. Back then NAPA had a rebuild kit - I don't know if they still do but it's worth checking into. I rebuilt my master cylinder and two or three wheel cylinders (at different times) and I never did anything more fancy than bench-bleed the master cylinder before installing it and then used the old tried-and-true pump-hold-bleed with a partner method that Squirrel recommends. I never even heard of "back bleeding" and certainly never did it on that car. Which I drove like a maniac and it always stopped really well with no pedal issues at all. Ever. (Except, of course, when a wheel cylinder went out now and then!) If that does not work then you have a bad master cylinder or a bad wheel cylinder or a leaking connection. Period.
Lots of good advice in this thread. I especially like the idea of using short lines from the MC outlet ports back into the MC reservoir to bleed it, never thought of that. Couple things I can add though, First as far as back or reverse bleeding there is available now a pump system to do this and they say in the web site literature that it's also great for hydraulic clutch systems. I bought one, but haven't used it yet. If I don't forget, I'll look for it at the shop after while and report back on it tonight with brand name and link. Another thing that hasn't been mentioned is "speed bleeder valves". They have a check ball in the valve so that you can open the valve, slip a hose over the ****** on the valve, route hose to a suitable catch bottle and then go pump the pedal with no air invading the system on the pedal back stroke. When you figure you've got that wheel cylinder purged of air, move to the next after closing valve. Just don't get carried away and pump all the fluid out of the master cylinder! Put a set of these on my OT daily driver recently and they worked great. Bought then @ NAPA. Dave
congrats man sounds like you found the problem. You've got to be feeling a little better now. I'm very interested in this tool. I should also note that I have never had to back bleed an American car. I have only had to do it on European vehicles and then only has a last resort.
Hitchhiker, This is the link for the back bleeders, both pro and DIY versions www.brakebleeder.com Dave
8 hrs a day for 25 years in a brake shop with as many as 4 techs and I never found it necessary to use a power bleeder of any kind. We had a basket ball style pressure bleeder in the back room collecting dust but we never used it. I have installed a few new defective M/cyls. and got them exchanged for good ones. That will confuse you until you prove that it is in fact a defective M/cyl. I have never encountered a M/cyl that got ruined by stroking the pedal too far. All of us knew how to pump brakes so that may be why. We never stood on the pedal after it bottomed. I don't understand why someone would. I find it interesting that the reverse bleeder linked above is marketed for anti-lock brakes. The manufacturers always recommended opening the bleeder screw on anti-lock systems when pushing the caliper piston back in for the expressed purpose of NOT allowing the brake fluid from being pushed back up into the system. That was a definite no-no. The potentially dirty or contaminated fluid came out the bleeder screw. They were worried about the small orfices in the valves of the systemgetting clogged with dirt. They recommended flushing any dirt or contaminants out through the bleeder screws. Forcing them back up into the system doesn't sound to smart to me. It would not matter on a 53 Pontiac of course.
I've gone through a bit of this lately since cobbling up a new brake system. I used a mity vac, what a piece. I tried a vacuum system using the compressor, too much h***le. I used the plastic tubes back to the master cylinder reservoir, what a fiddly leaky mess. Best results for bleeding calipers: speed bleeders attached by a plastic hose from home depot to a plastic bottle, submerged in brake fluid. Best results for bleeding the MC: plug the outlet ports, put it in a vice (by the ear, not by the cylinder) and used a plastic childs medicine syringe from rite aid(3 bucks) and filled the cylinder with brake fluid by shooting it into the ports. It's amazing how much fluid they hold, and how much air you get out of them. After that I filled a horse syringe with brake fluid (got off ebay for $5) , opened the outlet ports one at a time and shot brake fluid back into the reservoir with it, removing air. Once the bubbles were gone I put the plugs back in and tried to stroke the cylinder, hard as a rock. Then I threw it in the car and bled the wheels with the speed bleeders as described above. Worked for me, I was happy with the result, and I'll do it again in the future. I got the idea from R&C here, from this article about a brake diagnostic kit. I've been ***embling my own kit from various sources, I think it's fantastic.
I find that interesting as well. as I was taught it is defiantly a no-no to push fluid back up in an abs system as well. Not that it really matters... 98% of the jobs I do at Les Schwab get rebuilt calipers during the brake job...
policy is to replace all of the calipers when doing a brake job. It's not that they need them. They are built into the price. That is how we offer a 3 year, 25,000 mile warranty on brakes. but some are not available or we are doing a "special" job with no warranty for a customer without enough cash. We don't really have a service writer. But more of a Lead tech/brake manager/self imposed leader. Its a mad house. He makes most of the quotes and sales for the older techs that don't understand the computer system. I personally do all my own quotes, sales and repairs. It's much quicker for me that way. The only person I report to is the ***t. and general manager. It works out well, as I take some of his work load and I am left to myself. Not that we don't communicate and work well together. Management just won't give him any real power or ***le. I'm just a parts replacer and it ****s. But it's easy and it pays the bills.
I don't think that I could work for a company like that. just me. I understand the reasoning. I just don't agree with it.
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