Vacuum Pump hiss...
Thread Starter
|
Laughing Gas
Joined: Aug 2007
Posts: 1,132
Likes: 0
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
Likes: 1
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
Likes: 0
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
Thread Starter
|
Laughing Gas
Joined: Aug 2007
Posts: 1,132
Likes: 0
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
Likes: 0
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.
Trending Topics
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
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.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Postmaster
Joined: Apr 2008
Posts: 4,802
Likes: 1
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.
Thread
Thread Starter
Forum
Replies
Last Post
Ole' gray
1987 - 1996 F150 & Larger F-Series Trucks
11
Mar 2, 2019 08:50 PM
Mdc9966
1973 - 1979 F-100 & Larger F-Series Trucks
3
Mar 19, 2017 06:37 PM
