So I've replaced the master cylinder and booster on my 69 el camino and now I seem to be having some difficulty getting the brakes to work right. I bench bled the master as per the standard proces the manufactureer recommended. Got everything in the car and all the lines hooked up and started the bleeding proccess, RR, LR, RF,LF, and so on...Did the two man procedure and just kept getting air, did this for hours. Tried the gravity method for literally hours, never letting the master go dry. When I test drove the car the right front brake doesnt seem to be working because the car pulls hard to the left when you apply brakes. I replaced the soft line and installed speed bleeders and rebled the whole system again. I still seem to be getting tons of air out of the front calipers, I mean tons of air. I check for leaks and cant find any at all anywhere in the system. I even tried applying vacuum to the front bleeders and they seemed to start running clear fluid. but when I test drove they were spongy and the front right still was lame. Does this sound like I have a bad master cylinder? Ive done this job before many times and never had problems like this before.

possibly a bad proportioning valve. try bleeding it at all the fittings from the master cyl, to the prop. valve, to the tees to the callipers etc.

and when you bleed them the two man way are you having them pump them, and hold tight, open the bleeder, let it spit and close it before they release the pedal?

Do yourself a favor and buy a power bleeder,
http://www.motiveproducts.com/
Best money I have spent to date, one person, no air, on my G bodies I now have the best pedal I have ever had, I use to use the 2 person bleeding method,(getting the wife/kids to pump) what a PITA, now I hook up the bleeder and bam! great pedal by myself,, if you had this you would be done by now and driving your camino on the road:poke:, sorry but get this you`ll be glad ya did, matty man:beer:

If it was the MC, the frt left brake wouldn't work either. I'd suspect a bad RF caliper.

:poke:

I'd go with the right caliper first. I have to say tho, many years ago I had the same quirky problem with my 69 Camaro and it turned out to be the proportioning valve.

Before buying more parts try this 1st , make sure M/C is full of brake fluid open both front brake bleeders up a couple turns and stab brake pedal all the way to the floor 1-2 times , then close the left bleeder and gravity bleed the right side atleast 1 chamber full of brakefluid confirm you don't have anymore air coming out and then gravity bleed the left side the same way ( without touching the brake pedal ) . This has work for me in the past for recentering the prop valve on GM's & Fords , pedal should be firm and up higher when you get done . You might need to do it more than once but in over 30 years I have never had to replace a Porportioning valve .

You're right to question the valve, razor. failure is extremely rare. I've seen 3 in 35 years of wrenching. One was GM and two were old style Fords.

Rapidly pumping the pedal before bleeding a brake in not recommended, in the GM manuals, and I never do it, since the manuals say it induces air into the oil, which kind of makes sense when ya think about it.......

I think air has to be getting in somewhere and it has to be toward that Right side. Seems like enough fluid has been run through it to brake a whole fleet!

When I was working at a Chevrolet dealer in Pa. years ago a fellow brought in a Camaro that he couldn't get the air out of the brakes also, After talking to him I replaced the cups in the rear wheel cylinders, apparently he had boiled the brake fluid once or twice and one of the after effects was allowing air to enter the brake system through the rear wheel cylinders. That cured his brake problem.
Just when you think you have seen it all you find something like this.

Mike

I think m Zeigler is right- AIR is getting in somewhere- I would suspect the rubber lines- front or rear- replace em all- then rebleed system. have someone sit in drivers seat and hold constant pressure on brake pedal- check ALL connections for leakage. I once saw a mc leak air in thru the booster, but no leakage was visible because any fluid that leaked back into the booser was sucked out and burned in the engine- good luck :nanawrench:

#1. Did you have this problem before changing the master? If not, I would suspect it first. Probably a "remanufactured" so they say, unit. Many are junk out of the box. #2. Have you used the search function and looked for "theelcaminofactory"'s post on bleeding brakes? It may not help with your problem but at least for a while you will be amused. One of the funniest posts ever on this board, you rock Mike.

Thanks for the ideas guys, never let me down yet. Prior to changing the Master Cylinder and booster the only problem with the brakes prior to this was that at a long stop light the brake pedal would slowly make its way to the floor and brake light would come on ( hence my reasoning to change the MC and booster). I've bled this system so many times, must have runs a gallon or so of fluid through it during the process of bleeding and it hasnt gotten much better. I was inspecting the Hold off valve and its in pretty rough shape visually but like I said everything was working fine until I started wrenching. I know this happens especially in a car that has only driven 20,000 miles the last 17 years. I built a vacuum catch can and plumbed myself a vacuum bleeder set up using my vacuum pump I use for vacuum infusion. I'm going to basically start over this sunday by pulling the master and re bench bleeding it just in case. Anyone know a way to inspect or check a master to make sure its not leaking or sucking air? or will it be obvious once it happens.? I will probably just change the front caliper and run all new front lines (aready have a new set). If I still cant get a proper pedal and full function I'll swear up a storm, take up smoking again, and then try the hold off valve and proportioning valve attached to the frame. I've been doing brakes since I was 15 and have never had this much trouble with a bleedign job.

I have had my but kicked a couple of times when it turned out the front calipers were not floating/moving easily on the pins.

It might not be a bad idea to check the rubber line sections as well. Maybe with the new m.c. and better line pressures one swole or started leaking,. I've seen them leak and spray a super fine mist when the brakes are used. It makes finding a leak harder.