Anyone else having this problem? When I started it up the last two mornings, my exhaust brake wouldn't activate until the truck was almost up to normal operating temp. Later in the day after the truck has had a chance to cool off but ambient temperatures are warmer, it works fine. Any ideas?

 

Is your pac brake air operated or elec? If it is air you could have a leak in a line or at a fitting, if it is very cold there could be moisture in the line that is frozen , and once the eng temp gets up it thaws it out. Just a thought.

 

At night around here it only barely gets below freezing and warms up to mid 40's to low 50's during the day.
Both of course. It has an electrically driven air compressor. Sorry, couldn't help it. I'll check out the air line and connections today for a leak or possible moisture intrusion. It doesn't even sound like the compressor's trying to come on though.

 

I had the same problem with my Jacobs , turned out it was the ground wire, I guess the temperture change was just enough for the metal expansion and contraction....dont' know but it fixed it

 

Update: The compressor comes on and runs (it vibrates and gets warm, can't hear it over the engine though) but that's about it. Could the relay on the side of the compressor be sticking? Also, it's still under warranty. I haven't called the dealership that I bought the truck from yet, but would they warranty it since I bought it from them and they installed it when Jacobs had the hold on their brakes?

 

Apparently this is a known problem with the PacBrakes that operate off of a compressor which happens occasionally. The seal around the arm which turns the butterfly goes bad. When the metal heats up and expands it is still able to form a seal which will allow the brake to operate normally. Before warm-up and at highway speeds in cold weather it is kept too cool and won't seal. My appointment is Wednesday morning at the diesel shop where the dealership I bought the truck from had it installed.

 

Last Wednesday I took my truck up to Northland Diesel Service where the brake was installed. They found the problem to be a bad solenoid. Because it is a known problem, Pacbrake's fix for it is to replace it with a solenoid from a larger brake. So they ordered the part and replaced it on Friday. The new solenoid was large enough that they had to relocate it to the underside of the platform that the compressor is mounted on. Just thought I'd give you guys the update on what the problem was and what fixed it in case anybody has anything like this happen in the future.

 

Been following this thread, thanks for the update(s). Mine has been temperamental in colder weather, but it's quite a bit out of warranty now. Can you give any specs or numbers off that solenoid? Might just have to source my own...

 

tobyw - I was able to get Pacbrake's part number for the new solenoid. P/N is C11935. I just put a new pic in my gallery (pending admin approval) showing the size and location of the new solenoid. The old one is sitting near it on the radiator hose for size comparison. I would assume the location of yours is where my old one was: attached to the brass T-fitting on top of the compressor.

 

Wonderful!! I'll look for that pic as soon as it's posted...

Yes, mine is currently mounted off the brass tee. It's been staying warm enough at night the past few days that I haven't had a problem, so this may go away for me again for the next several months. But, I'd sure like to have it fixed before the cold settles back in next fall!!