1994.5 - 1997 7.3L Power Stroke Diesel  

Vaccum Pump Pressure?

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Old 01-21-2010, 10:03 PM
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Vaccum Pump Pressure?

Does anyone happen to know how much pressure the vaccum pump should create
Thanks
 
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Old 01-21-2010, 10:10 PM
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actually vaccum - suction should be about14-17inches of vaccum, i use that spec only cuz most cars operate there vaccum acc. at that level. Maybe working good at as little as 10inches.Haven't really ever measured it,are you having trouble with something not working?
 
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Old 01-21-2010, 10:16 PM
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yea breaks are fading! there are good enough brake pads on there and the lines have bean bled. just seeing if its the vaccum pump or brake booster
 
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Old 01-21-2010, 10:27 PM
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Definitly check the pump. I do recall talk about bad boosters at one time. Check the hoses from the pump, i've found mine loose ,cracked and needing replacing too.
 
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Old 01-21-2010, 11:14 PM
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the vacuum on my pump once read 5-7 inches of vacuum and i had no power brakes. got one from junk yard that read 22-25 and now good as new
 
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Old 01-21-2010, 11:18 PM
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i just checked my vacuum pump and had between 18-20 inches, my brakes are real soft so i decided to check the vacuum but i think its my master cylinder now.
 
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Old 01-21-2010, 11:38 PM
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id take my brakes being soft all day compared to having to pull the brake pedal back up with my foot like i do. any one know how to fix that?
 
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Old 01-21-2010, 11:39 PM
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dirty, when you didnt have power brakes, did heat selecter work? did it actually blow out the vents other than defrost?

i pretty much have no power breaks, and its somethin iv been putting off that i need to get fixed
 
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Old 01-21-2010, 11:48 PM
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happend in the summer... didnt check the heater i just started at the pump and that was around 5 when i heard it was suposed to be around 20. i think if you just start checking every vacuum line you may find a leak of some sort. but also if the check valve on the booster isnt doing its job right then that would also cause problems i would think.
 
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Old 01-22-2010, 12:09 AM
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this is a vacuum test out of chilton pro repair manual:
Vacuum Leak Test

  1. Operate the engine at idle without touching the brake pedal for at least one minute.
  2. Turn off the engine and wait one minute.
  3. Test for the presence of assist vacuum by depressing the brake pedal and releasing it several times. If vacuum is present in the system, light application will produce less and less pedal travel. If there is no vacuum, air is leaking into the system.
 
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Old 01-22-2010, 12:42 AM
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my heater only works on defrost i dont have anything coming out of my vents, i only have low speed to none of the other speeds work. Could this cause my brake problem?
 
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Old 01-22-2010, 12:50 AM
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Does your pedal fall to the floor at a stop or are they only squishy?
 
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Old 01-22-2010, 01:40 AM
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my brakes work there just squishy and pedel goes done pretty far, I bleed them a couple times, I have worst luck with the brake system i put all new lines on new brake cylinders brake booster and master cylinder all at once last year, and still have problems,
 
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Old 01-22-2010, 01:49 AM
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I have bad luck with brakes too. My current problem is that my pedal wont return without me pulling it back up with my foot. I hate brakes lol
 
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Old 01-22-2010, 07:36 AM
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Originally Posted by BigD7575
yea breaks are fading! there are good enough brake pads on there and the lines have bean bled. just seeing if its the vaccum pump or brake booster
When the vacuum pump fails the pedal will go rock hard.
Fading brakes usually means the pads or rotors are glazed (heat)
A soft pedal can be a bad master cylinder, air in the lines or a leak.
 


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