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Mar 31, 2011 | 10:51 PM

fordhorse

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Mountain Pass

Joined: Aug 2010

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vacuum pump

i think my vac pump is going out im hearing alot of noise and my breaks are very hard do i need a vacuum pump for anything other than the power breaks is there a way to test it to be sure that its bad thanks for your help

Mar 31, 2011 | 11:08 PM

oreocreaming

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Joined: Jan 2010

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From: Elk City, OK

yep, you need it to switch from vent to defroster. also cruise control if you have it. you can test it by hooking a vacuum gauge up to it. they go out all the time so my guess is thats exactly what it is

Mar 31, 2011 | 11:17 PM

fordhorse

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Mountain Pass

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guess that may be why the cruse control doesn't work how much vac should it have if its good

Mar 31, 2011 | 11:21 PM

wreckinball

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Joined: Apr 2009

Posts: 4,086

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From: Malahat/Cowichan Valley

username royzell has one, he lives a minute from me and is selling it for 50 i think, i have seen it and he showed it to me, pulls hard vacuum. hit him up!

Mar 31, 2011 | 11:23 PM

frodfreak

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Joined: Dec 2010

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brakes run off a vacuum so if ur pump were to be going out ur brakes wounldnt work as good as they use to, ur air controls runs off of vacum as well.

On vehicles with diesel engines, vacuum available to operate the vacuum booster brake is insufficient, therefore vacuum is supplied from a vacuum pump located on the top right side or left front side of the engine, Fig. 2. This pump is driven by a single belt off the alternator. These vehicles also incorporate a low-vacuum switch that actuates the brake warning light when vacuum is below a specified level. This switch senses vacuum through a fitting in the intake manifold that intercepts vacuum flow from the pump.

Mar 31, 2011 | 11:26 PM

frodfreak

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Disconnect the vacuum pump hose from the brake booster and insert a vacuum gauge. in the hose end. Run the engine at normal curb idle and check vacuum. Gauge should read 70kPa (21 inches Hg) at sea level within 30 seconds (refer to graph for vacuum at other elevations)

cant figure out how to post pics to show u the graph

Apr 1, 2011 | 07:17 AM

PLC7.3

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Joined: Nov 2004

Posts: 5,638

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From: Manitoba

93 speed control is electronic, the heater has a vacuum operated door on the heater plenum in engine bay.

Find the Tuna can on the front left inner fender behind the headlight........ disconnect the wire harness..... truck in park running at idle........ step on brake.

If dash light illuminates condition related to the hydraulic system, if not then the vacuum pump is problem.

If you would like the complete test email me and I will forward it to you......

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Apr 1, 2011 | 06:44 PM

bashby

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Joined: Nov 2005

Posts: 7,437

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From: Charles Town, W bygod Va

If you arent hearing a leak from the booster when you hit the brakes then your pump is probably weak.

Apr 1, 2011 | 09:51 PM

#10

frodfreak

Senior User

Joined: Dec 2010

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i have the steps on how to check the pump off alldata if that helps there in my albums, there are 2 it looks easy to follow

Ford Truck Enthusiasts Forums - frodfreak's Album: 1 - Picture

Apr 1, 2011 | 10:43 PM

#11

artfd

Elder User

Joined: May 2005

Posts: 567

Likes: 1

Quote:

Originally Posted by fordhorse

i tested the vacuum today and it pulled 20 but if you hit the breaks it drops to about 10 and makes noise whats the next step in testing

Test your brake booster cylinder independently of your vacuum pump. My truck doesn't have cruise control, but its symptoms were otherwise identical to the ones you have described. When I tested the brake booster with a $17 brake bleeder & vacuum pump kit, I found it leaked like a sieve and wouldn't hold its vacuum for more than a few seconds, way below its specifications. Check around on this site or elsewhere for the exact specifications of the test, it's been years since I did it. Here is one such site. Switching out the brake booster was much easier than replacing a vacuum pump would have been.
You could also have a leak in one of your vacuum lines, the 'kit' will help you isolate the lines & check them for leaks.
The 'kit' is just some vacuum tubing, tubing connectors, and a hand-operated vacuum pump. I'm sure its price has gone up.