Brake power boost problem
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Freshman User
Joined: Jul 2006
Posts: 37
Likes: 0
Brake power boost problem
I have a 95 350 with 160,000 miles. I have no power boost when the engine idles. The brakes work good otherwise with plenty of boost. As I come to a stop light, I keep my foot on the brake until it stops. If I release the brake and the truck starts to move, I have to stand on the brake to stop.
I suspected the vacuum pump but don't have a vacuum gauge. So I took the hose off the booster to check it and could feel a pulsating vacuum with the engine at idle. Also the heater/AC control vents work fine and they use vacuum to operate.
Where is my problem?
I suspected the vacuum pump but don't have a vacuum gauge. So I took the hose off the booster to check it and could feel a pulsating vacuum with the engine at idle. Also the heater/AC control vents work fine and they use vacuum to operate.
Where is my problem?
Junior User
Joined: Feb 2009
Posts: 53
Likes: 0
sounds like the vaccuum pump is going .... if will continually get worse.. apply the brakes while driving several times, if the peddle gets hard with repeat brake application the vaccuum pump does not have enough to pull the diaphram back. Sounds like it's weak due to low vaccuum at idle.
Post Fiend
Joined: Oct 2003
Posts: 5,903
Likes: 1
From: MICHIGAN
Your pump may be getting weak or have a very small leak. You can check for leaks w/o a vac gauge but it's better if you get one.
Apply the brakes after the engine has been shut down for about minute. If the pedal is rock hard you have a vacuum leak.
Apply the brakes after the engine has been shut down for about minute. If the pedal is rock hard you have a vacuum leak.
More Turbo
Joined: Dec 2002
Posts: 664
Likes: 129
From: Columbia, MD
Somewhere around 190 K my vacuum pump casing cracked... pump section separated from the pulley shaft. Heard loud knocking noise; stopped to check it, didn't see anything wrong. About 30 miles later, backing slowly into driveway, boost totally failed. Pulley and shaft were turning fine, but the pump was flopping around loose in the engine bay. Pump is pretty easy to replace. Even if you find a vacuum leak, check the pump casing carefully for any cracks. If you replace the vacuum pump, check your power steering pump. It's under the vacuum pump, so while the vacuum pump is off...
