First diesel truck - transmission behavior question

[jj46]

Hello guys/gals. I've owned 6 half ton Silverados and loved them all. On Friday, I bought my first Duramax... a 1-ton crew Z71 LTZ. So far I am loving it. Got 19 mpg on the long drive home from the dealership while in Minneapolis rush hour traffic. Not bad considering it only had 30 miles on it when I left the dealer.

 

I'm used to a "coasting" feel in the half-tons. For example, if I'm doing around 40 mph, and let off the gas, the RPMs drop, the torque converter unlocks, and the truck basically coasts with very little engine braking if any.

 

On this Duramax, if I am doing that same 40-45 mph and let off the gas, the RPM stays up, and there is significant engine braking... it doesn't feel like the torque converter ever unlocks. I guess I would say it's like driving a manual transmission.

 

Is this normal expected behavior? I feel like it's costing me MPG around town... if it's the expected functioning that is fine, but just something that really stands out to me as I get used to the new truck.

 

Thanks!

 

[doverarjim]

That is the Allison doing what the Allison does best. It is not a problem, like others will tell you we don't drive one ton trucks for the mileage!! First time you have a trailer behind you and take your foot off the foot feed and that thing slows down on its own you will be amazed. I love mine and use the engine brake everytime I start my truck.

[jj46]

It is not a problem, like others will tell you we don't drive one ton trucks for the mileage!!

 

 

Oh agreed completely, just wanted to make sure it was behaving as expected. I only have about 300 miles on the truck so far, so still getting used to it. It's a beast, no doubt!

[redwngr]

Allison is all about keeping the load under control -- more so than the 1500's.

 

After 10 years driving dmax trucks, immediately noticed the increased 'coast' on the 1500.

 

FWIW, we also run a late model impala, and if 'coasts' much further than the 1500.

 

 

Sounds like the 3500 is doing what it's supposed to do.

[Greenhound386]

Sounds normal to me, and I had a really similar experience. I upgraded from a 2011 Chevy 1500 to a 2017 Chevy 2500HD, and I immediately noticed the increased engine braking as well.

 

It's kind of like going from an inline 4 to a twin on a motorcycle (if you're familiar).

[jj46]

Perfect. Thanks for the responses guys. I figured that was the case, but just wanted to verify. These days with everything being electronically controlled, I just wanted to make sure the behavior was normal.

 

Looking forward to getting some miles on this thing.