'89 Chevy truck brakes


Old 05-30-03, 06:02 PM
CMil's Avatar
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'89 Chevy truck brakes

Okay. Same truck as before; my brother's '89 Chevrolet 4wd 1/2 ton with 5.7l v-8, auto trans and rear wheel anti-lock brakes. Now, when you push on the brake pedal with the engine idling, the idle speed increases (maybe 250-500 rpm) until you let off the brake; then, idle returns to normal. Brake pedal feel is the same whether the vacuum is connected to the booster or disconnected and plugged. This afternoon, while the engine was running, my brother laid an ear on the booster and said he could hear what sounded like air going through the booster. The truck DOES stop if you press on the pedal hard enough and have patience, but is unsafe to drive as is. And my brother's wife seems to have a thing for being able to stop when she wants to. Can a booster develop a leak like I've described? Or should we look somewhere else first? Any insight would be greatly appreciated; I'm already tired of messing with this beast. Thanks in advance - Chris
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Old 05-30-03, 06:22 PM
darrell McCoy
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my opinion would be is you have a diapharm that is kapoooot.
losing vac big time.
Old 05-31-03, 06:57 AM
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There's both a small filter and a check valve on the booster hose that goes to the back of the throttle body. Pitch both of those first and buy new Delco pieces. Any GM dealer or Delco parts distributor will have them.

If that works, you've solved your problem for under 30 bucks. Barring that, the booster is wasted.

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