Using jakes on long downhills

No. That's exactly how they are intended to be used.

 

Years ago (2008), had a friend get a brand new 4 axle heavyhaul rig. He pulled a 230k load through the mountains and jaked it all the way down. He got to the bottom and had to do a regen. The shoulder suddenly gave way. He looked in the mirror and saw the trailer and the stinger lean over. The the jeep. All he had time to do was grab his dog and hold on. The tremendous torque lifted the tractor in the air and slammed it on the ground.

I saw my buddy at HQ back in his old truck, putting his gear in. Now, to be fair, the company was known to get the new trucks in, run them through their shop, and jack around with the engine parameters. For example, in my company truck (pre regen), they cut my power from 455HP to 350HP. The truck was anemic! The engine blew at 119k. They put me in another truck and gave it the same treatment.

I get the feeling that if the company doesnt jack around with the factory settings on the ECM, it probably will be fine. I do know that if they cut them back too far, that affects EVERYTHING. Even the regen.

 

Ask the hotdog who jakes to a stop at the fuel pumps, he'll know for sure.

 

Not sure about that, but I definitely burn more DEF when I run the mountains vs running the flats. Few weeks back, filled up on Friday, truck sat all weekend. Monday and Tuesday ran Denver to Morrill, Ne. and back, I doubt if I burned 1/8 tank of DEF. Next three days ran Denver to Rifle, Co. and back. Come Friday, my DEF was almost on empty.

As for running jakes for ext. periods of time, every motor is different, but about every 200K you might need an overhead run if you notice the jakes aren't running like they should.

 

I don't get why you would pull over to regen. Running the motor decently hard should provide all the heat the DPF needs. I've never once needed to do a parked regen.

 

All kinds of things go wrong when the engine parameters are jacked up. I had a 9 speed top 2 transmission that was fine until they cut the power. It used to shift between 8th and 9th automatically, but when they cut the power, it would only buck back and forth in 8th. There was a way to bypass 8th, by turning the cruise off. It really hurt the performance losing 8th gear.

Those big trailers coming out of the mountains spend a longer time on the jakes than any other. Factor in a junky ECM tune, and you may problems that only similar rigs will have.

 

You'll also need to ask at the shop for an extra gallon of jake fluid to keep in the side box for a really long grade.