Tow/Haul Question

[Chris57k]

Hello Folks,

 

I finally found a 2002 K2500HD with the 8.1 and the Allison transmission.  Only had it a couple months and only one 350 mile trip.  Any body that has one, do you leave it in tow/haul mode all the time or just up and down steep grades?  I like the power and the hold back feature heading down hills.  Only got 7.8 mpg on my trip.

 

Thanks for any advice,  Chris

Edited September 23, 2019 by Chris57k
add trailer info

[Formulabruce]

Mileage is typical. I turn mine on and off, just make sure Im not lugging the lock up any. But steep? I do leave it on, and downshift sometimes. New trucks ( with cruise on) downshift but you cant even feel it.

[jake111]

As long as whatever you are doing doesn't cause jerks or clunks, then it's fine.   By that, I mean (for a Duramax, but I'm sure similar for you), for me, between about 28-48 mph the torque converter is locked up in T/H, but unlocked if not in T/H (generally).  If I am under slight acceleration/load and switch out of T/H in that range, the drivetrain gets a jerk/clunk.  So I don't do that.

 

I don't think it's as touchy engaging T/H in that speed range, but still I make sure there's no load so the transition is as gentle as possible.

[The Snow Punisher HD]

The Alison tranny is a masterpiece so I've heard. I have the 4l80e or something like that. 

Tow haul mode holds the gears longer hence higher rev limit and the deceleration feeling is because you're in lower gear.

 

Like other guy said mileage is Typical.

 

I have a tune on mine so my tow haul mode is reprogrammed but it won't hurt you

Unless you're doing it while moving. I hear that can cause long-term problems