Brake booster pump...help needed - Diesel Forum

waterdude · 06-13-2005, 01:28 PM

Greetings diesel friends,

I need help with a faulty brake booster pump (totally hard brakes, no vacuum assist).

I have the master cylinder unbolted and the vacuum hose disconnected from the booster pump.

Now what do I do?

Thanks in advance,

Hugh [img]/ubbthreads/images/graemlins/confused.gif[/img]

tim94f250 · 06-13-2005, 02:13 PM

First make sure your vacuum pump is not the fault. If it is the booster, remove the vac. line and check valve. Then inside, remove the cotter pin on the brake pedal arm. slide the pushrod off the arm. Unbolt the four nuts holding the booster. Then pull it out from the firewall. That's it.

waterdude · 06-13-2005, 03:30 PM

How do I determine if it is the vacuum pump or booster pump?

Thanks,

Hugh

biosdude · 06-13-2005, 03:46 PM

I just replaced my vacuum pump and I tested it by simply taking off the vacuum hose at the T by the firewall and seeing if there was any air getting sucked in by the pump. You could also loosen the belt and see if the vacuum pump pulley will turn easily by hand (indicates bad vacuum pump.)

waterdude · 06-14-2005, 06:50 PM

Thanks guys,

I'm checking out the vacuum pump tonight before going any further with the booster pump.

--Hugh [img]/ubbthreads/images/graemlins/grin.gif[/img]

cdnsarguy · 06-14-2005, 10:35 PM

Visit my gallery and do the vacuum test....

waterdude · 06-16-2005, 01:09 AM

I did the vacuum test and found that the vacuum pump was pumping low. I bought a replacement vacuum pump, pulled the pulley off the old pump with a pulley puller.

How do I install the pulley onto the new vacuum pump? Do I need a pulley installer?

Getting closer,

Hugh

Willie · 06-16-2005, 02:20 AM

Find a 2 inch long bolt that will thread into the center of the vac pump shaft, put a nut & washer on the bolt and then turn the nut, while holding the bolt this will pull the pulley on. If you can use a 3/4 inch - 1/2 inch drive socket instead of the washer and this will make it even easier to bring the pully onto the shaft at the correct depth. [img]/ubbthreads/images/graemlins/smile.gif[/img]

Weezer · 06-16-2005, 07:59 AM

Hugh, Like Willie said, you need to rig up the proper length bolt/nut combo to pull it on. Last time I did this, I got the pump from the stealership (ouch) and it came with the bolt and washer for replacing the pulley. If you put a stove washer on the bolt and run it down until the pulley is flush with the end of the pump shaft, you're done.

Keith

waterdude · 06-17-2005, 12:03 AM

Getting the pulley ON took a little time, thanks for the advice.

After reinstalling the vac pump tonight, I checked the new vacuum = 24 inches Hg, compared to 15 inches (old worn pump). Thanks for the help Pete, your vacuum diagnostic info sheet worked great!

All I have left is to return the old vac pump for core $$.

Final question: Why didn't my low vacuum pressure switch light up? My brakes weren't working and the Brake dash light was not on. Is it just an idiot light that lights when you have very very low vacuum or none? It came ON when I disconnected it. Wondering if I should replace it if it was supposed to work better than it did.

Thanks for all the assistance,

Hugh [img]/ubbthreads/images/graemlins/smokin.gif[/img]

Weezer · 06-17-2005, 10:03 AM

Hugh, when my pumps have died it was catastrophic- no warning and boom- gone. Then the brake light came on. So maybe there is a min. vacuum required to keep the idiot light from lighting up and you didn't get that low?? Dunno, but maybe you wanna see if the bulb is good?

Keith