1998 GMC C1500 Vacuum assist leak ?

1998 GMC C1500
136,000 MILES • V8 • 4WD • AUTOMATIC
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E.T.
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  • 1 POST
When I apply the brakes, most often, I can hear hissing under the dash where brake pedal rod goes through firewall. Sometimes it works fine, other times ,low speed in parking lot, pedal is hard, and brakes don't apply very well. (while engine revs are up-and-down a bit) . Is this a vacuum assist leak? Is that the round metal thing behind the master cylinder?
Oct 26, 2010 at 11:54 PM
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WRENCHTECH
  • ASE Certified Mechanic
  • 20,761 POSTS
  • ASE Certified Mechanic
Yes, that is the brake booster and it will need to be replaced.
Oct 27, 2010 at 7:08 AM
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