Seized Exhaust Brake and didn't know it!

[evotech]

Originally Posted by walt2137

Evotec I dont know what coach you have but the Monaco coaches will not activate the Pacbrake below about 10 mph, I did not say to take the air cylinder off, I guess I didnt explain my self clear enough what I do is unhook the power line 12 V(to keep from back feeding the computer) I leave the ground hooked to the Mac valve that activates the air cylender that closes & opens the pacbrake I hook 12v from a out source, starter or where ever to a push button type starter switch and with the air pressure up I cycle the pacbrake with the push button switch.

The procedure that I described is for a Jacob exhaust brake, not a pac brake.

[walt2137]

I should have said Jacob or Pacbrake exhaust brake, it would not make any difference which exhaust brake it would still not operate under 10 mph, that is controlled by the computer.

[chev]

Originally Posted by evotech

Just thought that I should share this story. I bought my 1998 HR Endeavor about a year ago. I had never driven or owned a class A coach before. When I engaged the exhaust brake it would slow somewhat, but nothing too dramatic. Fast forward to this week. I am preparing for a cross country trip with the family and going over every nut and bolt. I decide to take a good look at the Jacob Exhaust brake. Well, The butterfly valve was completely seized open and was not working at all. All that I really felt was the transmission downshifting. After a night of soaking in PB blaster and many hours with a hammer and other instruments of destruction, it finally freed up enough to start working it. I worked it back and fourth for hours with ATF fluid, PB blaster, motor oil ect...until it was totally back to normal. A quick test ride confirmed that it was finally functioning and boy what a difference.

I have found that you need to use the exhaust brake on and off several times, to leave it on all the time leads to those kinds of problems. One coach started up in the RV park and would barely run, the exhaust brake was open. It sputtered like it was running on 4 cylinders. Once the brake closed it ran fine. I talked to the CAT dealer about my C-12 engine exhaust brake and they said there was no need to lubricate it, just use it.

[Acker1]

On another forum, a Jacobs exhaust brake was discussed. I was told to put tranny in the default gear for the brake (usually 2nd or 4th), drive coach to get RPM's up, exhaust brake on, let up on throttle and you should feel it braking if the exhaust brake is working. If you don't feel it working---it's not.
DICK

[jimhfurlong]

I had exactly the same problem. (And the same fix) but now have a siezed air cylinder as well. *sigh*