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Vacuum Pump Going Out?

69K views 29 replies 22 participants last post by  kcb68 
#1 ·
Hows it going guys?

Truck is in the sig.

Here's what's going on. When I am moving the truck around I can hear a whining kind of sound when I step on the brake pedal.

Also, when I am coming down a long hill to a stop, before I come to the rear end of the vehicle before me, it's like I ran out of vacuum and I have to use my weight to stop the truck.

In other words, NO MORE POWER BRAKES.

By the time the light turns green, the power brakes are easily back.

This situation is getting more and more common.


The previous owner told me that he had replaced this pump a whole bunch of times before, and it might be going out again. Same symptoms I guess, and him replacing the pump fixed the issue.

Also, where can I get a new pump, and about how much will it cost me?

How do I replace the pump, is it pretty easy to do?

Is there a better, more-reliable pump available other than the one that Ford offers?
 
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#2 ·
Seems like it would be the Vacuum Pump, although you should also see the brake warning light on the dask flisker. The last one I got at AutoZone for about $110 (although that was a number of years ago. You will need a pump pulley puller to get the pulley off (one bolt will not clear the pulley). Cheers!
 
#3 ·
I forgot to mention the fact that the E-Brake idiot light does flicker, before.

I'm home sick today, so disorientation and sleep is preventing good thinking.


Thanks for the answer.


But I am kind of worried about the reason why this thing has gone out in the first place. When I bought the truck the guy I bought it from said that he had owned the truck for about seven years and he had replaced the same pump about 3-4 times I think he said.

Any ideas why he would have gone through so many? Maybe lack of quality replacement pump?
 
#5 ·
When I bought the truck the guy I bought it from said that he had owned the truck for about seven years and he had replaced the same pump about 3-4 times I think he said.

Any ideas why he would have gone through so many? Maybe lack of quality replacement pump?
Sometimes aftermarket parts are NOT as reliable as OEM parts. I replaced my vacuum pump with one from my local Ford store about 6-7 yrs ago, No problems with it.
 
#6 ·
My truck ate vacuum pumps I put about 5 on my truck in the 3 years I have owned it. Thats what it sounds like to me
 
#7 ·
Im trying to figure out right now what I am going to do.

I have figured that the 99-up electric pump may be an option because the pumping rate has little or nothing to do with what rpms the motor is turning.

I have had other little problems going on-nothing drastic, just had to replace the front seal behind the motor oil pump (better to get that while its in its mild stages), then this vacuum pump looks like its becoming a problem.

I guess that if I put the electric pump on the truck, then I'll have to gut the stock vacuum pump and leave just the bearings in or something like that to try to prevent having to get a different kind of belt.

Probably better to just not mess with it and put another mechanical pump back on?

My dad was just doing some research and he found out that the cruise control works off of the vacuum system too, which may very well fix my cruise control problem while we're at this.
 
#8 ·
You will have to switch to the hydoboost system like the SD's as the electric pump won't keep up with all the demands on an OBS. Cheers!
 
#9 ·
Ahhh, right on man.

Ill for sure stick with the mechanical one then.

Ive been getting a lot of mixed information from people outside of this forum that think they know a lot about cars.

Im pretty mechanically savvy and you guys have helped me a lot here, but others just over-complicate the issues that I ask about and dont think about it simply enough.

What i mean is, its just a motor-that happens to have some different parts in it and on it to achieve combustion and properly handle itself.


Thanks again, all.
 
#10 ·
Take a good look at the pulley on the pump. If its tweaked from not using the correct puller installer that may be the reason its eating pumps. Should be perfectly straight with no wobble with the engine running.
 
#12 ·
? don't know how much vacum, but the 1st one I had go out, you had to STAND on the brakes to stop; the second one, felt normal, it just caught the rubber hose on fire under the hood, I could smell something burning and pulled over. (tell me again, why do we like these trucks)
 
#13 ·
I had the vacuum pump on my '95 F350 go last summer and had the same symtoms. The brake light would flicker and eventually was coming on and staying on for a little longer each day; brakes were getting hard when the brake light came on. I replaced the vacuum pump and the vacuum would build up to 25 inches plus but would drop quickly and be slow to recover when I pumped the brakes. With the brake booster disconnected, the vacuum would skyrocket and recover quickly if I pulled a line. I had to replace the brake booster and then the vacuum pump would recover pretty quick and not get low enough to actuate the brake light.

One note. I didn't remove the pulley while the pump was in the truck. The one bolt that was under the pulley was the last one I removed and just moved the pump away from the block as the bolt came out. That way I could remove the pulley on the bench, much easier. Just DON'T forget to put that bolt back in its hole before re-installing the pulley on the bench.
 
#14 ·
. Just DON'T forget to put that bolt back in its hole before re-installing the pulley on the bench.

How come?? :lol::lol:

I have done it several times myself!!
 
#15 ·
Just replaced the vacuum pump on my truck a month or so ago. The only symptom that I noticed was that the cab climate controls defaulted to defrost. It wouldn't move to the heat or vent positions. That is now remedied.
The brakes act the same with the new pump as they did with the old worn out pump.
 
#18 ·
F6TZ-2A451-AA is the part number for a new vacuum pump from Ford for a 1996. 1994 uses a different pump. I prefer new as there are too many posts here over the years of repetitive failures of reman pumps. Not that expensive when you have time to order from Tousley Ford.

Vacuum should have nothing to do with cruise control on a PowerStroke. It's all electronic. The older trucks did use vacuum.

My 94 had a slowly failing vacuum pump that created the running out of vacuum you describe. It slowly got worse and eventually the A/C would blow out the defroster on start up. Once the RPMs were up it blew normal. When removed you could feel some suction when you spun it by hand with your hand over the fitting. Repeated the same with a NAPA reman pump produced at least twice the suction. So they can fail slowly. I swapped to hydroboost at the same time so I can't say how much the reman vacuum pump altered the brakes. It works fine for climate control.

On the 96 the vacuum pump bearing failed causing the pump to seize intermittently with basically no vacuum available.

When replacing the pump make sure you put the bolt(s) through the hole(s) before pressing the pulley on. There is at least one that you can get in/out with the pulley on. Been to long for me to remember which one but it's obvious on removal.
 
#19 · (Edited)
ive got a 87 ford f250 diesel 6.9 idi rear wheel drive with 113000. brakes got stiffer than a old man on Viagra and two belts got torn that connected to it . please someone tell me how to fix it . I messed up the pulley on the vacuum pump trying to get it off however ordered a new one along with belts and vacuum pump . I just bought the truck and it had been sitting for a while only being started once a month ..... help. { ill probably need more help once I order brakes, ive never done drums lol} this truck needs tlc , hoping to get it in great shape . I would love to use it for work, I am a commercial flat and steep slope roofer in the union , local 149.
 
#20 ·
If you are eating pumps, how are you installing the pulley? If you aren't getting the pulley on far enough or you are beating it on with a hammer, then that's why you're eating pumps. It needs to be pressed on using a bolt and washers. DON'T press or beat against the shaft without supporting it outside the pump. In other words do it the way the factory intended. Also go to a parts store that sells quality parts, if you want it to last.
 
#21 ·
Sounds like your truck has v-belts. You should re-post in the IDI section of the forum. But generally, to install a press-on pulley, you need a puller/installer tool made for the job. You can borrow (with a deposit) one at your FLAPS, or buy one at Harbor Freight for about $20.
 
#24 ·
Hi, I'm experiencing similar troubles...assumed vac pump failed / failing, replaced the pump but still getting stiff brakes (at idle) after a quick stab on the pedal.
I can pull around 26 in, stab the pedal, vac drops to around 10 in...then, when I release the pedal, gauge drops almost entirely to 0 and then draws vacuum down to the 26 in mark.
It does take (what seems forever) to draw back to 26 in...around 30".
With the gauge line tapped right into the main T, and engine stopped, the vacuum does slowly relieve...around 3 in in the 5 minutes I watched it (it was dark).
Thanks for any advice (I'm assuming it's the booster the way that it drops out after releasing the pedal but, thought before dropping another $150 I'd check with you guys.
Thanks for any advice.
 
#26 ·
I have a 2002 E350 Super Duty 7.3 L Turbo Diesel
1.- I had problems with a brake light on the dashboard ,following by a hard brake pedal.
2.- Diagnostic: I disconnected the hose coming from the mechanical vacuum pump located on the left side of the engine, I connected a vacuum gauge an the reading was 15 Hg of Vac. that means that the pump was giving weak vacuum since the normal vacuum is 18-21 Hg.
3.- Repair: I replaced the pump with a reman Cardone Vacuum Pump part # 641029 from Advance auto Parts. $118.00 with a pulley.
after installed I took reading again with the gauge an the reading was 26 Hg of Vacuum. I reconnected the hose back into the brake booster and Bingo. I got my brake pedal back and the ckeck brake light disappeared. installation time 1 hr.
good Luck out there
 
#28 ·
Try to find a place that sells new pumps and not rebuilt.

Other than that you could convert your braking system over to a hydra-boost system and then you would be able to use a Super Duty vacuum pump.
 
#29 · (Edited)
Agree on the new vs rebuilt, especially if the same brand rebuild has failed several times. I had several bad rebuilt starters in a row. Gave up and bought a new one. Problem solved. Also you read the part about making sure your pulley is straight right?
 
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