strokerace

I recently purchased my first cummins, a 95 2500 with a pacbrake on it. I bought it from a dealer so they didnt know much about it. There is a toggle switch in the cab that turns on the brake and sometimes it works fine. I have drove semi trucks with jakes so I know how they work, at least on those trucks. This one has me puzzled, sometimes you can flip the switch and go down through the gears coming up to a stoplight or something and it shuts off when you depress the accelerator or flip the switch off, it seems to work like it should. But sometimes it will not shut off, even when I turn the switch off the brake is still on and the only way it seems to stop it is to pull over and shut down the truck. Is there something wrong with the brake? Am I doing something wrong? I really like the way this thing works but am afraid to use it for the fear of not being able to shut it off. Any input would be greatly appreciated. I might be hauling some cattle next week and would like to be able to use it. Thanks

pind

First thing is to check pacbrake's website, and find the solenoid cleaning procedure. Take the control solenoid apart, and clean its internals. It can hang, causing the brake to stick in the on position.

Next thing, is to remove the clip holding the pin on the bellcrank for the exhaust butterfly. Turn the exhaust butterfly all the way around in both directions a couple of times. Over time, carbon buildup can make the butterfly stick in the closed position.

Next, lube all of the pivot points and recommended areas with a high temp silicone spray lube, pacbrake has a specific lube that they recommend, I have used others with varying success.

Re-attach the bellcrank to the actuator rod, and re-clip the pivot pin.

If there is still a problem, it is also possible to lube the actuator cylinder, once again using a recommended lubricant, through the vacuum ports.

in about 95% of the cases I have dealt with, cleaning the solenoid, freeing up the butterfly, and lube of the external pivot points is enough to ensure proper operation of the exhaust brake unit.

I am still scratching my temporal lobes over the sticking in cold weather issue though, I have tried many things, and still not 100% lucky so far.

I will say, if you have any technical questions, do not hesitate to call pacbrake directly. They have after sales service that I have found to be second to none in the diesel industry.

Good Luck

Harold-Pacbrake

I agree with checking your solenoid first, it more then likely just needs cleaning

cervri

I had this basic problem pleague me for quite awhile. It ended up being a Vacuum leak around the clyinder. Replaced the clyinder unit and all is good.

strokerace

I havent got around to cleaning it yet, my lift pump went out and I have been focusing on it and replacing worn out leaking fuel lines. Since I bought the truck with the brake already on it I dont exactly know what all the parts are and where they are located. Where exactly would the solenoid be located and what does it look like? Thanks

strokerace

Forgot to add that I have noticed that when its cold it seems to stick more. Also seems like when it does stick if I push in the clutch for a few seconds it will shut off, but then I'm free wheelin so it defeats the purpose of the brake. I dont know if that helps point out anything but I thought I'd be specific about exactly what it is doing. Thanks Again

CD in NM

srokerace.

You can go to PacBrakes website, there are PDF files for all the models of their brakes and the models of trucks they are installed on. If I were you, I would download the correct PDF file of the manual and installation for the year model of your truck so you can get a better picture. They also have parts diagrams of the brake models, that would also go a long way to helping you know the parts so you could order what you need. Give their service people a call, or e-mail them via their contact form, they would also probably e-mail you back the right PDF's that you need.

CD

Danavilla

CD gave you good advice. The solenoid valve will be upstream from the brake. Follow the vacuum line from the brake and the next gadget you find should be the valve. Follow the cleaning and assembly guide in the Pac Brake instructions and you're good to go.

Dan

dodgezilla04

the butterfly valve assembly(the bushings) will stick if not used often enough to keep the carbon build up off of it. the manual states to use the pacbrake lube annually on the moving components.

strokerace

I sent pacbrake an email, thanks alot guys, I think it sat on the dealers lot for a couple months so it may have been carboned up.

strokerace

Pacbrake sent me this in an email today. They said to try cleaning the solenoid first, then to do this test, I havent done it yet but they said if that didnt help me locate the problem to call them back and we'll figure it out. I just wanted to post these up here just in case anybody else might be able to use them. I give pacbrake an A+++++ for customer service, dont hesitate to email them or call them with any problems they are very helpful.

VACUUM CYLINDER TESTING
1. Remove both vacuum lines AT THE CYLINDER.
2. Block off either port on the cylinder with your finger and try to pull (extend) the cylinder rod out. YOU SHOULD NOT BE ABLE TO.
3. Remove your finger and pull (extend) out the cylinder rod.
4. Block off THE SAME port on the cylinder with your finger and try to push (retract) the cylinder rod in. YOU SHOULD NOT BE ABLE TO.
5. REPEAT STEPS 2 thru 4 for the other port on the cylinder.
6. If any time the cylinder moves in or out while you have a port blocked off, then the cylinder needs to be replaced. Part # C11898


7.* Please note if your brake does not work when the vehicle and outside air temp is cold do this test at the same or close to the same temperatures. Same goes for if the brake does not work when vehicle and outside temps are hot, try to do test then.

ONE NOTE TO ADD IT IS WITH THE VACUUM PORT BLOCKED OFF THE ROD WILL MOVE ABOUT ½” UNTIL PRESSURE OR VACUUM IS BUILT UP WITHIN THE CYLINDER.

ANOTHER TRICK TO USE IF THE ROD END WILL NOT HOLD VACUUM IS PUT A COUPLE DROPS OF PAC-LUBE TO THE ROD WHEN EXENDED THEN RETRACT IT AND PERFORM STEPS 2 THRU 4 AGAIN IF VACUUM IS NOW BEING HELD ON THE ROD END OF THE CYLINDER THE ROD SEAL IS DEFECTIVE.