A question for anyone that has had their truck for a long time, how long does a vacuum pump last? Miles/Years? Thought this might be handy to know with it being a problem for lots lately.

 

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.

 

I think the one on my dads 92 went 120k the first time, and the replacement is still goin, 135k later.

 

Not sure the mileage, but I got about 6-7 years out of the one on my dually. (It was a new one.) The one on it now is a used one, so who knows what I'll get out of it.

 

For those of you that have replaced your vacuum pumps: was the failure gradual? Or did the darn thing fail and left you standing on your brakes?
thanks

 

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.

 

Mine has been going out steadily it seems, just getting weaker. My dads locked up on em comin back from Reno

 

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?

 

I have not done the vac gauge like you have done but that pedal sounds exactly like mine.

 

either you have a hole in a large vacuum line, or your pump is bad.

 

mine holds vac. just fine.

 

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 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.

 

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.

 

Any updates? have you fixed your vac problem?