how can you tell when you hae a bad brake booster? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

meathead95 · 01-06-2008, 05:22 AM

my old one leaked when you hit the brakes so i replaced it. and now the pedal is REAL hard and the brakes arent that great? the truck has new calipers, pads, brake shoes, and wheel cylinders. any ideas?

71 super · 01-06-2008, 06:11 AM

I had one that did the same thing. There was some problem with the diaphram, replaced it and they startd working correctly. When motor has been running then shut off, if you pull the check valve out of the booster is there a sound of vaccum escaping? If not the diaphram is not working correctly and needs to be replaced. Hope this helps.

mbgmike · 01-06-2008, 07:48 AM

A hard pedal is one symptom of a bad booster. if you think about it. You have a spring assisted Diaphram thats using vacuum to pull it. If you lose vacuum or the booster diaphram is leaking it is now harder to push

meathead95 · 01-06-2008, 08:01 AM

i have good vaccum and i cant hear it leaking that is what made me wonder.

*72lb4x4* · 01-06-2008, 08:50 AM

With the engine off, step on the brake pedal and start the engine. The pedal should be hard with the engine off and then sink a bit when the engine starts.

68 50th · 04-09-2008, 09:26 PM

Quote:

Originally Posted by meathead95

i have good vaccum and i cant hear it leaking that is what made me wonder.

I have the same problem with a very hard brake pedal. Good vacuum, no leaks and I can clearly hear the vacuum escaping when I pull the check valve.
I have had both the master and booster out of the truck for cleaning and painting, could I have missed a gasket or something when I was putting it back?

**Already Gone** · 04-09-2008, 10:10 PM

Quote:

Originally Posted by 72lb4x4

With the engine off, step on the brake pedal and start the engine. The pedal should be hard with the engine off and then sink a bit when the engine starts.

If the pedal sinks when you start the truck, does that mean the booster and brakes are working properly?

jayharrell · 04-09-2008, 10:28 PM

http://www.classicperform.com/TechBo...tm#testbooster

This link helped me alot with braking issues. No offence, just a review of the basics.

01-06-2008, 05:22 AM	#1
meathead95 computer illiterate Join Date: Jan 2001 Location: Des Moines, IA Posts: 6,446	how can you tell when you hae a bad brake booster? my old one leaked when you hit the brakes so i replaced it. and now the pedal is REAL hard and the brakes arent that great? the truck has new calipers, pads, brake shoes, and wheel cylinders. any ideas? __________________ 72 2wd blazer 72 swb 4x4

01-06-2008, 06:11 AM	#2
71 super Registered User Join Date: Sep 2005 Location: Canton North carolina Posts: 3,079	Re: how can you tell when you hae a bad brake booster? I had one that did the same thing. There was some problem with the diaphram, replaced it and they startd working correctly. When motor has been running then shut off, if you pull the check valve out of the booster is there a sound of vaccum escaping? If not the diaphram is not working correctly and needs to be replaced. Hope this helps.

01-06-2008, 07:48 AM	#3
mbgmike Registered User Join Date: Aug 2005 Location: Pasadena,Tx /Pto Pta DR Posts: 5,415	Re: how can you tell when you hae a bad brake booster? A hard pedal is one symptom of a bad booster. if you think about it. You have a spring assisted Diaphram thats using vacuum to pull it. If you lose vacuum or the booster diaphram is leaking it is now harder to push

01-06-2008, 08:01 AM	#4
meathead95 computer illiterate Join Date: Jan 2001 Location: Des Moines, IA Posts: 6,446	Re: how can you tell when you hae a bad brake booster? i have good vaccum and i cant hear it leaking that is what made me wonder. __________________ 72 2wd blazer 72 swb 4x4

01-06-2008, 08:50 AM	#5
72lb4x4 Account Suspended Join Date: Jul 2006 Location: DFW Posts: 1,427	Re: how can you tell when you hae a bad brake booster? With the engine off, step on the brake pedal and start the engine. The pedal should be hard with the engine off and then sink a bit when the engine starts.

04-09-2008, 10:28 PM	#8
jayharrell Gettin By on Gettin By Join Date: Jan 2008 Location: Cedar Creek, Tx Posts: 1,033	Re: how can you tell when you hae a bad brake booster? http://www.classicperform.com/TechBo...tm#testbooster This link helped me alot with braking issues. No offence, just a review of the basics.



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