Vacuum Pump hiss...
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Laughing Gas
Joined: Aug 2007
Posts: 1,132
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From: Baldwin, ND
Vacuum Pump hiss...
Ok, forgive me if this is a stupid question! My vacuum pump hisses and blows air out the top through the openings while running. Is that normal? Also, my brakes seem to get hard after I pump them when the engine is cold. Is that a sign that he Vacuum pump is going out. I know that I need to test the vacuum to be sure but want to ask here before I go but the tester.
Thad
Thad
Post Fiend
Joined: Nov 2004
Posts: 5,638
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From: Manitoba
blows air out the top through the openings while running.
But the hissing......a damaged diaphram may do that.....
You will only get 3-4 pumps at best anytime........ our system is designed for application when required...... nobody pumps there brakes anymore.
Azone pressure and vacuum
Part Number: CP7803
Junior User
Joined: Oct 2008
Posts: 62
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From: Ludlow MA
vacuume pumps do go, i did mine like 2k ago, did my buddies 96 PSD over the summer to. my coffee can cansiter (on the driver side) had a hole from rubbing agains the washer fluid resivor cause the original owner never straped it back down after putting the plow controls in, and caused the whole problem, but the VP was dieing anyways
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Laughing Gas
Joined: Aug 2007
Posts: 1,132
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From: Baldwin, ND
If anyone really cares (I also post help others down the road!):
I read my online repair manual and found some info.
I omitted to mention that my brake light also stays on while it hisses and the engine is warming. It just so happens that the low vacuum indicator is the Brake Light on the dash. Thats good to know if yours stays on when the parking brake isnt applied.
So I will be going to buy another vacuum pump tomorrow.
Thanks
Thad
I read my online repair manual and found some info.
I omitted to mention that my brake light also stays on while it hisses and the engine is warming. It just so happens that the low vacuum indicator is the Brake Light on the dash. Thats good to know if yours stays on when the parking brake isnt applied.
So I will be going to buy another vacuum pump tomorrow.
Thanks
Thad
Posting Guru
Joined: Jul 2004
Posts: 1,627
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From: West Valley Utah
I had a brake booster that would hiss only when cold, had a hard pedal also. Fine when it warmed up or in the summer. Since it was the wife's winter driver, I changed it and the master cylinder. The parts came together at a price only 10 bucks more than just the booster alone.
That was quite a few years ago so prices are most likely not the same now.
That was quite a few years ago so prices are most likely not the same now.
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Post Fiend
Joined: Nov 2003
Posts: 21,285
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From: Nutter Fort, WV
I just changed my vacuum pump this winter.
On very cold mornings the low vacuum indicator would stay on for the forst mile or two driving.
Never listened for a hiss, so it could have been there, but I was not to concerned since the only thing my vacuum pump now runs is the heater controls.
Low vacuum indication is when the brake light is on or the heater will only blow out of the defroster vents.
On very cold mornings the low vacuum indicator would stay on for the forst mile or two driving.
Never listened for a hiss, so it could have been there, but I was not to concerned since the only thing my vacuum pump now runs is the heater controls.
Low vacuum indication is when the brake light is on or the heater will only blow out of the defroster vents.
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Yes, Dave has a Ford hydroboost unit, bet he's loving it too. As my sig reads, I run a Suburban hydroboost, essentially the same thing but for various reasons it worked out better for me. I never had my vacuum pump hiss at me, even tho it's shot (hence the hydroboost conversion), but it does take a bit to build up enought vacuum to get the air vents moving like they should. Also, my low-vacuum switch never engaged, I know the light works so I'd assume switch was bad - removed the thing anyways, don't need it with the hydroboost.
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