Any Diesel shifting problems?

MattFL · May 17, 2016

Has anyone with the diesel experienced any transmission issues at all?

I'm shopping the diesel, and I came across numerous complains about the transmission they used in the v6 (same as the diesel?). For example

http://www.carcomplaints.com/Chevrolet/Colorado/2015/

http://www.carcomplaints.com/Chevrolet/Colorado/2016/

Mostly complains about it getting stuck in 5th or 6th gear and not downshifting as needed. Has anyone with the diesel experienced any transmission issues at all?

newdude · May 18, 2016

Duramax Colorado/Canyon does use the 6L50 but with some changes, the biggest being the torque converter.

The Duramax 2.8L is the cleanest diesel truck engine ever produced by General Motors, and meets some of the toughest U.S. emissions standards, thanks in part to a cooled exhaust gas recirculation (EGR) system.

Additional features included with or exclusive to Colorado diesel models:

Smart diesel exhaust brake system that enhances vehicle control and reduces brake wear on steep grades

Standard Hydra-Matic 6L50 six-speed automatic transmission matched with a Centrifugal Pendulum Vibration Absorber (CPVA) in the torque converter, which reduces powertrain noise and vibration

An all-new integrated trailer brake controller is standard and exclusive on diesel models

A 3.42 rear axle ratio is standard.

The CPVA is an absorbing damper with a set of secondary spring masses, that — when energized — cancels out the engine’s torsional vibrations so the driver and passengers can’t feel them. In its unique design, the spring masses vibrate in the opposite direction of the torsional vibrations of the engine, balancing out undesirable torsional vibrations.

The Colorado’s integrated, driver-selectable exhaust brake system is based on the system introduced on the 2015 Silverado HD models and uses the compression power of the engine to improve vehicle control and reduce brake pad wear.

When the exhaust brake is engaged in cruise mode, exhaust cruise grade braking helps the cruise control system maintain vehicle speed when travelling downhill, keeping the driver from having to apply the brakes, thereby exiting cruise control.

In non-cruise mode, the transmission and the exhaust brake deliver the correct amount of braking to assist in vehicle control, regardless of vehicle load. It is a smart system that varies the amount of brakes needed for the vehicle, load and grade. The engagement of the system is smooth and quiet, while its performance enhances the driver’s feeling of control.

If anything, the 2.8 with that transmission probably drives better than the 3.6 as the 3.6 is a very rev happy engine, where the 2.8 works down low with a much shorter RPM range than the V6. You have to wind it right the F#@ out sometimes for it to really go. Those complaints you linked most likely could be solved for those folks with a reprogram of the TCM and ECM as there is an updated software for the issues they are having.

Pinnacle · November 23, 2016

GM sells this tranny to BMW and they use it in the X1 and 3 series. Not as beefed up though.

HondaHawkGT · May 3, 2017

Has anyone with the diesel experienced any transmission issues at all?

I'm shopping the diesel, and I came across numerous complains about the transmission they used in the v6 (same as the diesel?). For example

http://www.carcomplaints.com/Chevrolet/Colorado/2015/

http://www.carcomplaints.com/Chevrolet/Colorado/2016/

Mostly complains about it getting stuck in 5th or 6th gear and not downshifting as needed. Has anyone with the diesel experienced any transmission issues at all?

90% of those complaints are due to the same transmission tuning characteristics that the GM half-tons get complaints over. The tuning is designed to maximiz2 fuel economy. The 2015+ Ford F-150 and 2016+ Toyota Tacoma get similar complaints for upshifting early, trying to hold gears too long, lugging the engine up hills, etc.

Luckily tuning is an easy way to make the truck shift however you want it too. You can also shift gears manually. I did it for a few months before I got mine tuned and after a while it became as natural to do as shifting with a stick shift.

mjcmichigan · September 26, 2017

I have the 2017 GMC with the Diesel 4 cylinder. Loving it. I commute with it and do the hunting fishing thing. Over the first 4700 miles my odometer says the average diesel mileage is 27.8 mpg. Highway trips its 30+, around town 22-23.

Yes it holds the gear on grade, but it holds the speed and I found grades it would down shift.

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MaverickZ71 · May 10, 2018

In the old days, the Hydramatic Division made some of the best automatic transmissions in the world. But now GM tunes most all of its auto transmissions to shift into overdrive as soon as possible, no matter what the conditions. Supposedly in the name of fuel economy. All it does is bog the engine down. So you stamp your throttle foot down, which results in a two second delay, a massive downshift, and screaming engine. As soon as you lift your throttle foot one iota, the PCM nannies shift back into top gear, and the maddening process starts all over again. Doesn't matter if it's a 6 speed or a 10 speed, if they can't learn to program the tuning logic any better. We don't need any of those middle gears when it consistently upshifts from 2nd gear to 6th gear or 3rd gear to 8th gear. When the driver complains, GM says 'normal operating parameters'. We call BS--other manufacturers have figured it out, for instance, Ram's 8 speed in their 1500's has a good reputation for driveability and offers comparable economy. At that rate, I'll bet the joint-venture Ford/GM 10 speed ends up shifting better in the Fords than it does in the GMs. I have read where the torque of the baby Duramax and the tuning is well suited to the Colorados/Canyons, resulting in better truck-style driveability than the 3.6L gas versions.

newdude · May 11, 2018

Having reached 17,000 miles on mine, I guess I can add some to this.

GM tuned the 6L50 with the 2.8 Duramax to operate just like the HD trucks. While the 1/2 tons want to get to the highest gear as quick as possible, the 2.8/6L50 package will hold the gear its in and almost runs a bit of speed "limiting" before it goes to the next gear. What I mean by that is, if you are doing 50mph, it won't touch 6th gear at all, where a 1/2 ton would drop to 6th at 40mph. It wont shift to 6th until 55mph. The HD trucks drive this exact way as well. Its quite the potent little powertrain as well, and I've averaged 25.5mpg on my Trip B which has never been reset since day one.

mjcmichigan · May 12, 2018

Having reached 17,000 miles on mine, I guess I can add some to this.

GM tuned the 6L50 with the 2.8 Duramax to operate just like the HD trucks. While the 1/2 tons want to get to the highest gear as quick as possible, the 2.8/6L50 package will hold the gear its in and almost runs a bit of speed "limiting" before it goes to the next gear. What I mean by that is, if you are doing 50mph, it won't touch 6th gear at all, where a 1/2 ton would drop to 6th at 40mph. It wont shift to 6th until 55mph. The HD trucks drive this exact way as well. Its quite the potent little powertrain as well, and I've averaged 25.5mpg on my Trip B which has never been reset since day one.

I have the little Duramax in a Canyon. Have almost 15k on it. It’s very drivable. The tranny does behave pretty good. On a trip to Canada on the 90km/hr highways, it was taking 8% grades to make it drop to 5th. Held the speed perfectly, and no heavy lugging.

I think you are right. Comes down to who is doing the tuning.