C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

High RPMs, no brakes

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Old Aug 7, 2012 | 11:17 AM
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Default High RPMs, no brakes

New problem, new post.

I took care of the leaking china walls on my '89 TPI recently. After putting everything back together I'm getting an INTERMITTENT high idle (1-1.2K), and no brakes. The car runs great, but the brake pedal requires both feet to stop the car from 25 mph (hard pedal).

Now, my first thought was the brake booster, but it worked before the tear down. So, unless I banged it up during the process, I'm also skeptical that is the issue.

Other vacuum lines were tested by removing them and/or carb cleaner.
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Old Aug 7, 2012 | 12:22 PM
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Somehow your brake booster vacuum hose is not connected correctly resulting in a vacuum leak and not enough vacuum to the booster. Check the hose and anything that t's off of the hose.
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Old Aug 7, 2012 | 12:33 PM
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Originally Posted by 383vett
Somehow your brake booster vacuum hose is not connected correctly resulting in a vacuum leak and not enough vacuum to the booster. Check the hose and anything that t's off of the hose.
But the line from the plenum to the brake booster check valve has been checked and double checked.
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Old Aug 7, 2012 | 12:34 PM
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Check both ends of hose and booster fitting.
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Old Aug 7, 2012 | 01:20 PM
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Sure sounds like a vacuum leak. Check for addiquate vacuum right at the booster.
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Old Aug 7, 2012 | 01:33 PM
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More of a question than an answer - is it possible to put the check valve in backwards?
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Old Aug 7, 2012 | 01:38 PM
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Originally Posted by aminnich
More of a question than an answer - is it possible to put the check valve in backwards?
It is not.
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Old Aug 7, 2012 | 03:30 PM
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Well if your hose and connections are not leaking, somehow your booster is busticated.
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Old Aug 8, 2012 | 10:45 AM
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Originally Posted by 383vett
Well if your hose and connections are not leaking, somehow your booster is busticated.
Yeah, was hoping that wasn't the case. It is frustrating that a "simple" gasket repair has turned into something bigger.
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Old Aug 9, 2012 | 10:56 PM
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Default fixed it

Problem solved: cracked brake booster. Crack originated from the point closest to the header, so it's fair to say that heat may have been a factor.

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