Booster Problems?
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Booster Problems?
G'Day boys and girls.
My name is Jay, and i'm a noooob (here at least). I MOD over on an S-series forum.
Anywho, the Van is my In-laws business delivery van. It is a 1998 E350 with a 7.4 Powerstroke. I suspect the brake booster has gone for a crap, as it has all the typical booster going for a crap symptoms. I would like to first and foremost check the vac pump to make sure it is pulling the correct amount of vacuum, and also to check the booster check valve, before I pull the booster. My question is, does anyone know the spec for the amount of vacuum that the vac pump should pull? I have all the tools and whatnot to do the job (I am a Farm Equipment Mechanic, or Diesel Ag-Tech).
Thanks,
Jay
My name is Jay, and i'm a noooob (here at least). I MOD over on an S-series forum.
Anywho, the Van is my In-laws business delivery van. It is a 1998 E350 with a 7.4 Powerstroke. I suspect the brake booster has gone for a crap, as it has all the typical booster going for a crap symptoms. I would like to first and foremost check the vac pump to make sure it is pulling the correct amount of vacuum, and also to check the booster check valve, before I pull the booster. My question is, does anyone know the spec for the amount of vacuum that the vac pump should pull? I have all the tools and whatnot to do the job (I am a Farm Equipment Mechanic, or Diesel Ag-Tech).
Thanks,
Jay
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Joined: Sep 2010
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From: Monmouth County, NJ
I realize it's highly unscientific but I usually just put my finger over the rubber hose coming off the pump to see if there's vacuum in the first place. In my experience these things either work 100% or not at all.
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Yea, I pulled the vac line off the booster, and there is Vacuum there, I just wanted to make sure. The in-law says its good for about 2 brake applications, then the pedal goes rock hard. Slip it into neutral, rev it up a little, and the pedal starts to come around again. Im 90% sure its the booster.
Jay
Jay
Fleet Mechanic
Joined: May 2011
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From: Thornhill , Ontario
A weak vacuum pump or vacuum tree leak also causes those symptoms.. Does the heater controls work properly...the default postion is Defrost On a Diesel , Hard pedal ussually points to the pump....If the pedal goes all the way to the floor it is usually the booster or if your hear a hiss....I forget the spec on the vacuum but if you post on the Diesel forum someone will know....
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I will have to have a look at the heater controls tomorrow night. I guess if the mixer doors are slow or inoperative, it would make more sense to look for a vac leak, then the pump. Does everything come off the vacuum manifold mounted just under the cowel?
Jay
Jay
Fleet Mechanic
Joined: May 2011
Posts: 1,414
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From: Thornhill , Ontario
Yes it comes from the back of the pump to the tree and the from the tree to the booster and other lines.....you have to check all of them...Mine was acting funny and the light ( brake) was slowly coming on and going away when it was cold (-10C)...It was the spring clamp on the tree going to the booster that was a little weak. I put a regular hose clamp instead and it stopped...be careful that plastic can be brittle....
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Well, I replaced the booster today. Problem still exists. No vacuum leaks at the vacuum manifold below the cowl. All the spring clamps are still good and strong and not sprung or warped in any way shape or form.
I made a thread over in the diesel section inquiring about vacuum pump specs and how much vacuum it is supposed to pull.
Thanks for everyone's info and advice.
Jay
I made a thread over in the diesel section inquiring about vacuum pump specs and how much vacuum it is supposed to pull.
Thanks for everyone's info and advice.
Jay
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