Trying to track down a vacuum leak. To test a brake booster, do I just hook up a Mityvac to the booster check valve, pump and see if the booster holds vacuum. It is a dual diaphragm brake booster if that makes a difference.
Testing brake booster for leaks.
- Thread starter Clone TIE Pilot
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I can't give you the answer but way back, I had a bad idle on my SBC and I traced it to a leaking booster check/one way valve. I clamped the hose and the idle improved.
Wouldn't a leaky booster lose it's vaccum quickly once vaccum source is removed?
Watching this thread to learn
Wouldn't a leaky booster lose it's vaccum quickly once vaccum source is removed?
Watching this thread to learn
if there was a leak you should be able to hear it if you turn the engine off. Plus if you leave the car sit for a few hours and remove the fitting on the booster you should hear the rush of air to fill the cavity caused by the vacccum
If it is leaking, if you disconnect the booster and plug the line from the carb, the idle speed should slow down. Your test with a mighty vac should do the trick to check it. If it isn't leaking, its not bad.
This guy is great. We used him to repair the booster for my Dad's Galaxie.
http://www.boosterdeweyexchange.com/
http://www.boosterdeweyexchange.com/
Hooked up the Mityvac to the Regal's brake booster and was only able to pull 5 inhg with very hard pumping which slowly bleed down to 0. As a control group, I also tried a brake booster on my friend's 2004 Ford Taurus, and I was to pull 17 inhg easily which it held without bleeding down. Doesn't look too good for my booster. I am going to try replacing the checkvalve and grommet first to see if it will solve the issue.
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If the booster was leaking shouldn't the pedal be hard as well as a hissing sound
On my Dad's Galaxie, it didn't provide adequate assist but the pedal wasn't rock hard. We could not hear hissing.
It may not be a total failure but enough of a leak to upset the engine. My booster is a double diaphragm so perhaps one is leaking and the other is still ok so it half works? It having such a lower reading than the Taurus booster is not a good sign. The Regal booster is also much harder to pump vacuum with the Mityvac than the Taurus booster. Looking online, it seems the Taurus uses a single diaphragm which might make a difference.
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