Power Brake Booster
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Elder User
Joined: Mar 2004
Posts: 500
Likes: 1
From: Penndel, PA
Power Brake Booster
Hey Guys...
I'm chasing down an annoying brake problem that I believe to be my power brake booster. I've recently replaced all brake lines, master cylinder, calipers and drums. Did plenty of bleeding. Brakes feel spongy, mostly when I'm at a stop light for a while. Started about 2 days ago. Occasionally I'll try to stop and pressure won't be there right away. Normally I would expect this to be a loss in hydraulic pressure, but it does not do this while the truck is turned off. The brakes are nice a stiff when the truck is off.
No obvious leaks in booster, couple of rusty spots but nothing serious. Before I go spending a lot of money on a brake booster...anyone gotta way to test my booster? Anyone experience this before or can give me a more definitive answer as to what the problem may be?
Thanks for your help.
I'm chasing down an annoying brake problem that I believe to be my power brake booster. I've recently replaced all brake lines, master cylinder, calipers and drums. Did plenty of bleeding. Brakes feel spongy, mostly when I'm at a stop light for a while. Started about 2 days ago. Occasionally I'll try to stop and pressure won't be there right away. Normally I would expect this to be a loss in hydraulic pressure, but it does not do this while the truck is turned off. The brakes are nice a stiff when the truck is off.
No obvious leaks in booster, couple of rusty spots but nothing serious. Before I go spending a lot of money on a brake booster...anyone gotta way to test my booster? Anyone experience this before or can give me a more definitive answer as to what the problem may be?
Thanks for your help.
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
It's not your booster. A bad booster can only cause a hard pedal, never a soft one.
Can elaborate a little more on exactly what happens? Does the pedal sink? Do the brakes work OK but just have a low pedal? Does pumping the pdeal help?
Can elaborate a little more on exactly what happens? Does the pedal sink? Do the brakes work OK but just have a low pedal? Does pumping the pdeal help?
Senior User
Joined: Sep 2004
Posts: 174
Likes: 0
New parts aren't always good parts. Seems like the more we import from third world countries the worse the quality gets. I have found several parts defective right out of the box in the last couple of years. Makes you start to wonder about your troubleshooting abilities when you're sure you know which part is bad and the problem stays the same or changes a little after you replace it. Your problem sounds to me like the master cylinder is bad. I would take it back and get another one.
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
I'd start by making sure the rear brakes are adjusted correctly. They should lightly drag all the way around when you spin the tire by hand.
Then, it sounds like you may have gotten a bad master cylinder. When you have a sinking pedal, and there are no leaks, it has to be in the master cylinder. There really is no way around that. Make sure you have use a quality replacement, i.e. stay away from Autozone/Kragen parts.
Then, it sounds like you may have gotten a bad master cylinder. When you have a sinking pedal, and there are no leaks, it has to be in the master cylinder. There really is no way around that. Make sure you have use a quality replacement, i.e. stay away from Autozone/Kragen parts.
