ToronadoGuyDenver

I've been trying to figure out how to tell whether or not my 1985 Oldsmobile Toronado has a Vacuum switch or not?

I put a new Booster on and the pros at AutoZone didn't know either and I got one with the switch. The brakes are horrible even after putting on a new Booster, Master Cylinder and brake pads.

Can anyone tell me how to know whether my Booster has or needs to have a vacuum switch?

Also, if anyone has any advice on brakes here's the problem.

Even after replacing all the parts listed above and of course bleeding the brakes several times, the brake light still comes on and the brakes go to the floor. It always stops but not like it should of course. I believe it to be possibly an electrical problem? I'm just not sure after doing all that I have.

I am considering putting on an entire brand new brake system which could cost me lots beyond what I've already spent. Also, maybe I should take it to a shop and have them bleed them and see if that helps? Maybe there's air stuck in the line? I wouldn't think so, but.... Also, maybe it has something to do with the Vacuum switch issue?

Thanks for your help

ozoneblue

Try gravity bleeding, first .Open all 4bleeder valves .remove cap &let set keeping resevour full.Be paitent go get your favorite beverege 1, Unless you have a helper 2. RE CHECK LEVEL. I use a AC vac pump & clean bottle.Bleeding 1 at a time,also flushes the system ps buy plenty of fluid

ToronadoGuyDenver

Are you saying to loosen all bleeders on each wheel at the same time and take the cap off without pumping the pedal? It wouldn't seem like it would go out the bleeders unless your pumping the brakes?

texasred

I like the "one man brake bleeding tool" they sell at Poop Boys and Auto Zoo for less than $10. It's a tube with a one-way valve. Start at the wheel farthest from the booster and work your way forward. On cars with a newer style proportioning valve, the valve will "close" if the master cylinder runs dry (to prevent pumping out all the fluid if there is a leak). Look for a "button" on the valve and reset it before starting.

C.J.

Oldsguy

I just drew a blank on the nomenclature, but what about the block that distributes the fluid from the master resivoir to the wheels? It has a different name but looks the same if you have disc fronts and drum rears. What is that thing called?

texasred

I only know it as a "proportioning valve", if that's what you are thinking of....

"Mind reader? I'm barely a mind user!"

C.J.

Oldsguy

That's it. I read a post once where the proportioning valve was corroded on the inside caused a partial blockage to one of the lines, screwed everything up. I don't think they are too complicated, but they are also not that expensive so it might be a cheap attempt at fixing your problem.

ToronadoGuyDenver

I've heard of a proportioning valve but don't know where it's at? Remember guys, I've blead them out several times and it never is right? I'm not saying that maybe there's not air somewhere in the line, it's just hard for me to believe that as well as I've blead them previously that that's the problem. This proportioning valve seems to ring some bells as I've heard something of this before. I'm trying to think of what it is or looks like. Also, I might look into getting one of these one man bleeders and try it myself again but since I've already blead them several times with the same result, I'm looking at other options.

Thanks for all your feedback and help guys.

Oldsguy

follow your brake lines from the master cylinder down to a machined block on the frame rail, usually behind the lower radiator support, inboard on the frame rail. That's it.

ToronadoGuyDenver

Several times I've heard the same thing and yes, I believe the proportioning valve is the problem. The cars parked for now so I looked and found it. I'm going to get a new one. With any luck, it will solve the problem. I bet it does!

Dapapadon

Your problem sounds like you got a bad rebuilt master cylinder. If you're not losing fluid i.e. MS stays full. And you're sure you have the system bled correctly. Then it's back to the master cylinder.

I've heard stories of guys going through 3 or 4 rebuilt ones before they get a good one.

Jim's rare 80

Hey. When you replace the proportioning valve remember to bleed the brakes in the right order. Do RR, LR, RF LF, and check fluid level after each wheel, just to be safe. You don't want to start all over again. I hope the valve works for you, after all, it has the switch that turns your brake light on.
Happy stopping.

Bluevista

I just went through the same thing on my '71 Vista Cruiser, it was a bad "new" master cylinder like Dapapadon said. You did bench bleed the master cylinder and the booster pushrod is the right length?, shouldn't push the MC piston in when mounted or the brakes will never work right, just touching is usually about right. One weird thing is I went to the brake bleeding procedures in the '71 Olds chassis service manual and it said to bleed the brakes in exact reverse order as commonly done, left front - right front- left rear- right rear. I used my Mity-Vac (great tool to have for lots of things) and did it by myself according to the manual and they work fine now, car stops good as they ever did (they don't brake like new cars), and the brake warning light went out after a few pumps.

Allan