PacBrake Sticking
 

My PacBrake has started to stick on. Of course, at first I suscpected the flapper was the culprit. However, that does not seem to be the case since the brake activates easily. Has anyone had the vacuum valve go faulty on one of these units?
george

I do not have one on my truck but will, so I guessing , disconect the down pipe and linkage and see if its carboned up[ moves freely] , if so then carb cleaner will work with moving by hand the valve , if not then it may be the bronze bushings , thats if its stiff to move by hand , if it moves freely than the control may be the problum, is yours vacume or electric , I think that they have a spring for return to off possion[ that may be bad] the control turns it on the spring turns it off.

If you have 385,000 km on that engine, it might be time to replace
that brake unit. I am sure it has stopped your vehicle and paid for itself "well" over ??

Thanks, guys, Yep, it is well over 385 now. The unit is vacuum, and I think it uses vacuum to return the unit instead of a spring. I am going to take the vac control off and test it.

There are three trucks I work on that have had this problem with Pac-Brakes.
First off I'll say that Pac's customer service is second to none, they have provided free replacement parts on units that are over five years old. Just give them a call.

First step is to remove the vacuum switch and totally take it apart and clean thoroughly.
If that doesn't get it the problem is the cylinder, non repairable, you will need a new one. This where their excellent customer service comes in.

Thanks, Bill. I cleaned up the vacuum solenoid and things are better, except that it still takes a little shot on the accelerator to get the brake to disengage. Thanks again for te suggestion.
george

So, after cleaning the unit still reacted slowly. I took the valve apart and removed the spring. Now, everything seems to work well.
WHO KNOWS???

Maybe you have a vacuum leak somewhere else?

With the vacuum pump on the 94, there is never enough vacuum. However, with that little spring removed everything seems to work well.

Thanks again, Bill.