Brakes hard to press, barely stopping.

So, I got the wagon going yesterday. Felt good to drive her again. One of the major problem. The brakes are hard as hell. Seems like no power at all. It barely stopped when I parked at work. Then again when I pulled in to park. Had to hurry and put her in neutral to keep her from jumping the curb.

New master, brake booster, and front brakes within the past few years.

Another big thing is the idle it is way high. it is not on choke. you need to really hammer the throttle to get it to idle normal. Not even touching the idle screw. I can force it but jumps back to high idle.

Tim

 

Sounds like the booster is bad. Sometimes the master cylinder leaks out the back in to the booster and kills the seals?

Just a thought, but I would check the booster first.

With regard to the high idle, try some carb cleaning spray on the outside of the carb first...

 

my manual brakes were horrible when I first started driving my 66. Couldn't get hardly any brake action at all. Replaced a bunch of parts, adjusted things....turned out to be a collapsed hose to the rear brakes and all was good.

 

Here is a link for some simple tests. Similar to what is in the Buick Chassis manual.

http://mbmbrakes.com/brake-booster-diagnostics/

 

Booster issue. Check the hose from the booster to the intake manifold. If that is ok, your booster is most likely leaking vacuum. You may be able to hear a hissing sound near the source of the leak (possibly from under the dash near the brake pedal)

 

Figure it out yet?

 

I had a power brake booster check valve malfunction once, took me a long time to find the problem. Ten dollar part.

 

Great thread here….from when i bought my car the pedal seemed odd, I vacuum tested and have 20 at idle. The master was leaking so replaced it and now it feels normal on a first application but I am experiencing a hard pedal on a second plus applications, the master cylinder was leaking at the booster so suspicious of the booster but now that I read this thread I can do more troubleshooting….Gord

 

I had the same problem with the brakes on a 72 442 fastback.

First time on the brake pedal felt fine, second application not real good, third time it was done and the brakes were hard as a rock.

I had put a W-31 cam in the motor and it was making no vacuum. Had to add a vacuum canister and then everything was fine.
Duane

 

Check valve was ok but My booster is faulty, I put a vacuum pump on it and it wouldn’t do anything, I performed the same test on my car with good brakes and it built vacuum. New booster is on its way, thanks Todd M.

 

Replaced the booster, brakes are working as they should. Fun job replacing it, lost some skin and practiced my swear words

 

Struggling with the same problem. Very hard pedal and not stopping very well. It just feels like old manual brakes. I replaced the Booster and master. Just a bit better. Booster holds vacuum fine. I can check it days later and still has vacuum when I remove the hose and valve. I don't just want to replace everything. I can hear the vacuum assist when I hit the pedal.

 

Do not overlook pads/shoes, rotor and drums for glazing or contamination of the linings.
Worse on drums, but the linings on both pads and shoes can really get slick/hardened and once that happens, the heat and slipping just make it worse. If you find your butt nearly a foot of the seat, your leg ramrod straight and your doing your best Jim Carry face, it might bad linings.

 

I once had a problem like that and the culprit was the check valve. Did you replace yours when you changed the booster?

 

I did replace the check valve when I replaced the master and booster. Disks in front drums in back.
The pedal will go down a bit when I start the engine after I pump it with the engine off.
The initial action feels like regular power brakes and then gets really firm, just like manual brakes.
This is a 1970 GS with the hold off valve and a distribution block.
Scratching my head. The guy I purchased the car from felt the pedal was a bit soft so he replaced the master. When it was unloaded from the truck it was really firm like no boost. He sent me a new booster and master and it is better, but not right..

 

Thanks for the ideas. I did check the vacuum and I have 22 at idle, so not that.
I have the original master cylinder and it is the oval reservoir with the round 2 bail lid. Te replacement I received is the rectangular style. Maybe not the correct one. I think I am going to buy an replacement booster and master along with a new hold off valve. just working through the system.

 

the last two cars I had with really hard to press and ineffective brakes ended up being the flex hose from the chassis down to the rearend and t-block. Hoses has collapsed on both and the car would hardly stop and the pedal was stiff as a board.