Exhaust brake does not work as it should

Restless · 11-23-2010, 04:44 PM

My 2000 Dutch Star does not seem to retard as good as it once did.

Has anyone had this problem? Mechanic says it is working OK. The transmission shifts down, but I do not feel the slowing like I think it should. Plus on long down grades 6% or more the motorhome is in white knuckle mode.

Could the Butterfly be corroded or broken?

I think the air cylinder is working.

GaryKD · 11-23-2010, 05:26 PM

Hi Restless,
Was the concern on your bill and did you pay for the diagnosis? If no, I do not believe a thorough diagnosis was completed. Consider getting an authorized service center to do a thorough diagnosis of your concern.

**"007"** · 11-23-2010, 07:03 PM

Is it your PAC BRAKE your talking about.

Lug_Nut · 11-24-2010, 08:33 AM

Restless, Just a thought, are you sure you are not starting the grade at a higher speed than previous therefore descending in one gear higher? A 6% grade would require no higher than 4th gear, possibly 3rd depending on the terrain. 5th gear has far less affect on Pac Brake application.

Peter

Restless · 11-24-2010, 05:27 PM

Yes it's the pac brake, aka an exhaust brake.

Restless · 11-24-2010, 05:33 PM

I was in 1st gear and was using the footbrake to keep speed down, so transmission would not shift up to higher gear. White Knuckle ride with no runaway ramps.

Stillwater · 11-24-2010, 05:52 PM

Quote:

Originally Posted by Restless

I was in 1st gear and was using the footbrake to keep speed down, so transmission would not shift up to higher gear. White Knuckle ride with no runaway ramps.

?? 1rst gear? What was the grade? how long was it? what was your ground speed, what RPM was your engine running? Like was said before ya gotta be in the groove to get the Pak brake to work to full effect.

GaryKD · 11-24-2010, 06:12 PM

Hi Restless,
How do you know you were in first gear? With the Allison, you can request any gear you want. However, the tranny will not shift toward or into that gear until its' computer says it can do so safely. If you were in 1st gear, your speed would not have been greater than about 10 MPH.

The bottom line is get the exhaust brake checked out by an authorized service center and a certified tech.

Shaun and Amy · 11-25-2010, 06:44 PM

I had, what sounds like, the same problem on a 2000 Freightliner. Everything was working, but the valve inside wasn't moving. In talking with PACBrake, they said that corrosion and brake dust will cost them the fail after several years. The tolerance is very tight inside, which is the problem. So, I bought a new one and installed it. It's actual an improved version, because it now has two stages. I'm very happy with the new one and it's back to working perfectly.

Good luck with your's.
Shaun