Community Forums

TonyMac · 02-17-2018, 12:31 PM

With the engine off and cold, can anyone move their pac brake valve by hand? Mine does not move, and the braking from it is not impressive, especially considering the Jake compression release brake from my long past life. I'm thinking my valve is stuck and all I'm getting is downshift braking. What do you wise folks think?

scampers227 · 02-17-2018, 02:01 PM

You should be able to move it against the spring with a screwdriver or pliers. Just checked mine and lubed it today.

FIRE UP · 02-17-2018, 02:19 PM

I think I've tried to move mine too while doing other maintenance in the area and, could not move it. But, it's always worked flawlessly each and every time I've needed it. I do keep it lubed on a quite often basis. I've even tried to loosen the air fitting on the back side of the piston so inject my home compressed air to the movement and, I can't break the fitting loose. I'll have to try again sometime. But, to answer your question, I've no experience in actually moving it when parked.
Scott

JEEPOHOLIC · 02-17-2018, 10:29 PM

Mine was stuck open when I bought my truck, some advice from a member of the Freightliner RV haulers group told me to disconnect the air ram cylinder and you should be able to move it by hand, if not spray some lube on the shaft and get some plyers to move it back and forth, he also said to leave it on all the time so it gets used or it may get stuck again, there is a special lube to use on the shaft, I find keeping it on and moving and a spray of WD-40 works well

TonyMac · 02-17-2018, 11:17 PM

Yep, got the special lube, and have applied it per directions several times per year. I use the brake often, but don't leave it on because, as I remember, that results in too much downshifting for my liking.

Bigd9 · 02-18-2018, 06:06 AM

I can't move mine by hand, but I can move it using a pair of Vice Grips.

Here is a link to Exhaust Brake Maintenance Tips. Note all of the places they recommend using their oil:

https://pacbrake.com/wp-content/uplo...7/08/L5046.pdf

FormerBoater · 02-18-2018, 02:51 PM

It should move very easily by hand with the cylinder disconnected.

dbywaters · 04-03-2018, 08:47 AM

I added a switch allowing me to test and exercise the brake.. sorry about the audio.. but diesels are noisy..

https://www.facebook.com/doug.bywate...3906877900483/

glenn allen · 04-11-2018, 10:47 PM

If you disconnect the air hose to the pac-brake then you should be able to overcome the spring pressure and move the shaft from open to closed. If it will not move with moderate effort then use some rust buster on the shaft where it goes through the cast iron housing. Not wd40 it will burn and gum up from the heat. Treat both the top end of the shaft and the bottom end This is the most likely place for it to seize. If this does not work then take it out and do some bench work on it.

TonyMac · 04-12-2018, 06:48 AM

I disconnected the air line, and was able to move the valve by prying with a big screwdriver. The spring is really strong, and pulls it back to open with a serious amount of force -- a lot more than I expected. But there is no binding, it is a smooth and very forceful operation. It will not move with the force of a bare human hand, the spring is too strong. I put a several drops of Pac Brake Lube in the cylinder while I had it open.