piperman60

Hello all , Hope everyone is safe and well. Just need some advice to do with the brake booster on my 58 Olds, Please, I recently removed the booster and installed new o rings , leather plunger cup etc . I bled the brakes and also installed a new vacuum return valve on the booster line, as it still had the original on it ,i took the car for a few drives and if i touched the brake pedal too hard it would nearly put my head through the windscreen, but now the brake pedal has gone very hard? I I have checked the fluid level in master cylinder and it is still full to the top! Any help or advice would be great, Many thanks in advance, Ray, Brisbane.

Tedd Thompson

Sounds like your Treadle Vac, booster tank or the new valve may have developed a leak. To chase it down start the car and let it run for a few minutes shut it off and pull the hose going to the treadle vac. There should be a sucking sound if not move back to the to the tank and do the same test if no suck move on back to the hose next to the carb. Some where ether something was assembled in improperly or a piece of junk managed to get stuck in one of the valves.

You might try also pressing hard on the brake peddle then start the car and try and feel if the peddle drops as the vacuum increases. It should move about a 3/8 inch if it does you might have a a brake line collapse or something unrelated to the Treadle Vac it's self.... Just a few thoughts.... Tedd

piperman60

Cheers Tedd, I will check the lines out, There is a great deal of vacuum suction from the line that goes into the back of the carby so at least that is ok, , i must admit that the lines to the air storage tank etc are still the originals so i should replace them, Cheers again ! Ray.

piperman60

Hello again Tedd, I tried the pump up the brake pedal and then start motor, no movement in pedal. i also tried the run for a few minutes option as well and turn off motor, but no suction when i pulled vacuum line apart, Will take out booster and check it out, Lucky it only takes about ten minutes to remove, Cheers ray.

Tedd Thompson

Check the tank also, both hoses,,,,Tedd

Nomadoc

My 57 has a steel tube that runs across the bottom of the firewall that connects the booster vacuum to the vacuum canister. Mine had a big hole from rust.
I’m not sure if you have the same tube in the 58 but it might be be something to look for....
Bill

Tedd Thompson

In 56 they changed the tank and where it was located but I didn't realize they changed the attachment system. In 55 it was all hoses and simple clamps might be even more different in 58. But still follow the loss of vacuum from the carb to the tank to the booster somewhere the vacuum is being lost. The system is still very much like the earlier models as there both Treadle Vacs and have remote booster tanks.

Have you used a stethoscope and listen for a sucking sound. Just a thought...Tedd