1999 Dodge Caravan VACUMN BOOSTER

Tiny
JIM HAAR
  • MEMBER
  • 1999 DODGE CARAVAN
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 90,567 MILES
When I push the brake pedal, while driving, I hear a vacumn leak and the brake pedal pressure is higher than it should be.
I think the booster is leaking and needs to be replaced, but want to know if the vacumn check valve could be the problem?
Thanks, Jim
Thursday, August 27th, 2009 AT 2:19 PM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
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.
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Thursday, February 25th, 2021 AT 8:34 AM

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