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Re: power booster Posted by DougM [Email]  (#211)  [Profile/Gallery]
(more from DougM) on Wed, 6 Dec 2006 06:29:26
In Reply to: Re: power booster, Kevin, Wed, 6 Dec 2006 00:58:01 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I found this post on another non-saab automotive forum, and it pretty much mimicked my thoughts on brake booster/power assist units...saves me from having to type it out myself. If you think about what power assisted brakes does for you, then what is posted below will make alot of sense.
"There should be no spongey pedal if you unhook the booster from the system although it will be hard(meaning it might take two feet applied to the brake pedal to stop the car) there still should not be a spongey pedal. To check the vacuum booster, pump the brake pedal with the engine off until you've bled off all the vacuum from the unit. Then hold the pedal down and start the engine. You should feel the pedal depress slightly as engine vacuum enters the booster and pulls on the diaphragm. No change? Then check the vacuum hose connection and engine vacuum. If okay, the problem is in the booster and the booster needs to be replaced.
Vacuum boosters also have an external one-way check valve at the hose inlet that closes when the engine is either shut off or stalls. This traps vacuum inside the booster so it can still provide one or two power assisted stops until the engine is restarted. The valve also helps maintain vacuum when intake vacuum is low (when the engine is under load or is running at wide open throttle). You can check the valve by removing it and trying to blow through it from both sides. It should pass air from the rear but not from the front."
No vacuum assist = hard brake pedal.
A leak in the boosters diaphragm is a vacuum leak, so it may actually have some affect on how the engine idles/runs, depending on how large the leak is. If the leak is large, you may actually hear an air leaking sound when you depress the brake pedal.
posted by 68.171.93...
, Tue, 5 Dec 2006 05:17:14, Thu, 21 Dec 2006 07:53:03, Wed, 6 Dec 2006 06:29:26 <-- Viewing This Message
, Wed, 6 Dec 2006 06:44:50, Thu, 7 Dec 2006 18:39:04
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