Vacuum question
Elder User
Joined: Mar 2004
Posts: 588
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From: El Dorado Co., CA.
108K on my 1991 F250 4X2
For the last several years, it's been my "dump run" and "move the boat" truck.
Back in 1999 to 2001, My father in law owned it and towed his fifth wheel. It didn't take him long to want a powerstroke. I bought it and am happy. It's my daily driver now that my car spun a bearing. I miss the cushy ride of my olds, but truck is doing it's job.
For the last several years, it's been my "dump run" and "move the boat" truck.
Back in 1999 to 2001, My father in law owned it and towed his fifth wheel. It didn't take him long to want a powerstroke. I bought it and am happy. It's my daily driver now that my car spun a bearing. I miss the cushy ride of my olds, but truck is doing it's job.
i ain't rite
Joined: Mar 2005
Posts: 65,561
Likes: 5,599
From: Marlboro Mental Hospital.
the first two were with the manual trans, so i did not know they were bad until until i went for the brakes and it was like stepping on a brick.
the last one was with the auto trans, and i noticed it was not shifting properly.
the one in it now has around 140k miles on it.
the last one was with the auto trans, and i noticed it was not shifting properly.
the one in it now has around 140k miles on it.
Elder User
Joined: Mar 2004
Posts: 588
Likes: 0
From: El Dorado Co., CA.
OK. It happened again on my commute home in the warm afternoon. My Brake light came on, as did my (rear) anti-lock light. I parked the truck at home and left it running. hooked up my vacuum gauge and it was pulling 22Hg. I had my daughter press the brake several times while I watched the gauge. The more she pushed the brakes, the gauge went down. When she'd stop, the vacuum would build back up slowly. The pedal is firm, but not like when there is zero vacuum. Before I got home, i tested the cruise control and it worked.
any thoughts?
any thoughts?
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Thread Starter
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Posting Guru
Joined: May 2011
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Likes: 1
Okay, sorry for not getting back sooner but ive been busier than a one armed paper hangar. So to test if it was the vacuum pump, i started by disconecting the vacuum line coming from the pump where it T's into the splitter thing.
I then attatched the line to my vacuum guage, to get a reading directly from the pump. After idling for a few minutes it had stayed steady at about 24HB, and stayed there even after shutting her down for about 5 mins.
So having found that my pump was good to go, i moved on to testing to see if it was the a vacuum line or possibly leaking at the T. I disconnected the vacuum line from the brake booster at the valve and hooked it up to the guage.
At idle, it only got to about 22 HB, and lost pressure as soon as i killed her. So i know its leaking in the lines or at the T. My dads works at Oriellys so hes picking up some caps for me tonight and tomorrow ill go through and cap the lines one at a time to find it. Much easier than going through and hooking the guage upto every line. Will update
I then attatched the line to my vacuum guage, to get a reading directly from the pump. After idling for a few minutes it had stayed steady at about 24HB, and stayed there even after shutting her down for about 5 mins.
So having found that my pump was good to go, i moved on to testing to see if it was the a vacuum line or possibly leaking at the T. I disconnected the vacuum line from the brake booster at the valve and hooked it up to the guage.
At idle, it only got to about 22 HB, and lost pressure as soon as i killed her. So i know its leaking in the lines or at the T. My dads works at Oriellys so hes picking up some caps for me tonight and tomorrow ill go through and cap the lines one at a time to find it. Much easier than going through and hooking the guage upto every line. Will update
Elder User
Joined: Mar 2004
Posts: 588
Likes: 0
From: El Dorado Co., CA.
I didn't think to see if my system was holding the vacuum after shutdown. good idea. I'm going to work the troubleshooting like you did. thanks for the post. I'll post again after my tests.
Thread Starter
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Posting Guru
Joined: May 2011
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YEah, because if you have it running would still be generating vacuum. And also, if the needle on your guage is bouncing around alot, its most likely leaking somewhere, because it should hold steady as it rises and be still when its at max pressure. Just a thing i learned lol. Just take it a step at a time by isolating it, the pump, then to the T, and then the lines if nessicary. if its your pump it will have low numbers and wont hold.