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#1 |
Senior Member
Join Date: Sep 2004
Location: Georgia
Posts: 614
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Brake pedal on my truck is hard to push. Brakes feel spongy so I'm certain I need to bleed the system, but how can I test the power brake booster to see if it if functioning properly?
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![]() 2012 Silverado LT 1500, 5.3, 6 speed auto '86 SWB C-10 Silverado |
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#2 |
Love that '69
Join Date: Oct 2005
Location: Sherwood Park, Alberta, Canada
Posts: 109
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Re: How do you test a power brake booster?
The easiest way......Take the truck for a drive and slam on the brake pedal. It should stop very quickly and almost throw you out of your seat.
If you originally had manual brakes and converted to power brakes, one drive and you'll know the difference. Plus, you should always bleed your brakes after you disconnect any lines. I did mine when I converted to a power brake booster.
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I AM CANADIAN & PROUD OF IT!!! ![]() 1969 Chevy C10, SBC V8, TH-350 Transmission, Metallic Blue, B&M Megashifter, GT Grant Steering Wheel, 2.25" True Dual Magnaflow Exhaust System w/ SS Magnaflow Embossed Tips, 700W Rockford Fosgate Stereo System, Lowered 1" Front & Stock Rear, 4.56 Rear with Positraction, 15" Chrome Rims w/ Chevy Center Caps & Michelin Tires, 4.5" K&N Air Filter, Edelbrock 'Elite' Engine Accessories, Chrome Powdercoated Engine Parts 2001 Cavalier Z24, 2.4L DOHC, Silver, Spoiler, AEM Intake, 2.25" Magnaflow Exhaust System, Clear Euro Tails, Tinted Windows, 400W Clarion Stereo System |
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#3 |
Senior Member
Join Date: Sep 2004
Location: Georgia
Posts: 614
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Re: How do you test a power brake booster?
Well, I'm still building on it so I can't take it out on the road. Trying it in the yard though, the truck will stop, but its not a throw you out of your seat stop. It's more a hard pedal and a spongy stop. Doesn't feel like its working at all, but then again, it might just be that the system needs bleeding/adjusting real bad, so that's next. I was just wondering if there was some test, i.e., vacuum test or something to tell if it was working properly. Easier to replace it now while the fenders are off than later. Thanks.
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![]() 2012 Silverado LT 1500, 5.3, 6 speed auto '86 SWB C-10 Silverado |
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#4 |
To The Levy
Join Date: Jan 2007
Location: california
Posts: 391
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Re: How do you test a power brake booster?
Hey Crawdad, I have my own way of checking to verify booster is good or bad, I usually pump all the air out of booster by operating brake pedeal about three to four times firmly with engine off. than while holding the pedal down I start engine, if the booster is good, vacuum will pull the pedal down just a tad, usually about a 1/4"....... hope this helps and if I am wrong, please feel free to correct me, also there is usually a hissing noise when brakes are applied with engine running, or engine shakes and runs rough when pushed hard and engine is running, sorta like a vacuum leak, good luck
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#5 |
Senior Member
Join Date: Nov 2005
Location: northwestern wi
Posts: 2,111
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Re: How do you test a power brake booster?
hard peddel ,little brakes =bad booster, often times you will have a bad vacume leak as well
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common sense isn't so common anymore |
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#6 |
"Trucks with Class"
![]() Join Date: Jul 2000
Location: OLYMPIA, WA, USA
Posts: 8,132
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Re: How do you test a power brake booster?
I use a vacuum pump with an in-line vac gauge and shut off valve. Draw 20lbs and close the valve. The booster should hold that reading and not leak down (diaphram leaks). You can even operate the booster by hand with the pump drawing vacuum and see that is is working freely.
Another test is to run the engine to draw vacuum, shut off the engine and wait about 30 seconds, then pull the plastic valve off the booster...you should hear the vacuum bleeding off if there are no leaks. |
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#7 |
Senior Member
![]() Join Date: Sep 2014
Location: Wenatchee, Wa
Posts: 910
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Re: How do you test a power brake booster?
Old thread but very helpful! I just tried both methods and the brand new 2 year old booster won't hold any vacuum.
Thanks to all! Blake |
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