Chevy diesel questions and concerns

[jamesu]

Not sure if this is the correct blog category but I'll start here.

I bought my used 2011 Chevy Duramax/Allison tranny a year ago. Love it. It was the first diesel I had ever driven, and because of that I believe that I am still learning stuff. I heard/learned some stuff the other day that I am considering which I will relate here.

My neighbor has basically the same truck as me: a 2012 GMC Denali Duramax/Allison tranny. He is towing a large 5th wheel and has had several diesels before this. You can see my TT below in my signature.

When I tow I always push in the "tow" button at the end of gear station. My neighbor only pushes his button when going up hills and mt. passes.

When I tow I have rarely used my jake brake, thinking that the gearing in my "tow button" position is sufficient when descending hills/mt. passes, having heard that my Allison transmission is "bullet proof". When towing my neighbor immediately pushes his jake brake button when he starts the engine and keeps it on all day.

My questions: Who is towing correctly? By keeping his jake break button activated all the time is his engine at any risk? Or are my brakes/transmission at a risk because of the way I rarely use my jake brake?

I have searched my truck's owner's manual and also the internet for answers to these questions and neither was much help to me.

My dashboard readout states that my average overall MPG is 15.2 mph while my neighbor's overall readout is 18.1 mph. Neighbor says it's because I am using the "tow button" feature when I am towing, and he is only using it when the tranny starts "searching" going up hill.

Feedback to my questions and concerns are appreciated. I have a great tow vehicle, and I want to get the most out of it when towing and I want to be able to be towing with it for a long, long time.

Aside: I am, and have always been, a stickler for keeping up with planned maintenance on all of my vehicles.

[jamesu]

Thanks for the info. I learned a lot from you guys.

[N-Trouble]

1) Its not a "jake" brake...

2). Why wouldnt you want to tow with tow/haul ON and exhaust brake ON??? Much more enjoyable tow.

3) Turn it all off when empty. Brakes on these trucks are plenty capable.

[JIMNLIN]

op wrote:
When towing my neighbor immediately pushes his jake brake button when he starts the engine and keeps it on all day.

My questions: Who is towing correctly? By keeping his jake break button activated all the time is his engine at any risk? Or are my brakes/transmission at a risk because of the way I rarely use my jake brake?

Your neighbor is a wise man.
Its a great feature for slowing down the truck when empty in city traffic or towing a heavy trailer. He won't hurt the diesel by leaving it on full time as the later model Dmax/A with the turbo brake keeps the torque converter clutch locked in all gears except 1st gear. Your turbo brake acts like a exhaust brake.
Your Dmax doesn't have a jake brake.

I have the Jacobs exhaust brake on my Cummins with the NV5600 manual tranny. I keep the brake on just about all the time especially in stop and go traffic when empty. With over 280k miles no problems from doing so.

Turn it on and enjoy its benefit......all the time (except wet/icy roads).

[Greene728]

Keep doing what you're doing cause you are right. I would recommend though that you use the exhaust brake more often. No, it doesn't hurt a thing to use it as that's what it was built for. Matter of fact, your better off using it more often rather than less.

[6_6_Oilburner]

Michelle.S wrote:
There is another feature in TowHaul mode with the Allison. It locks up the torque converter earlier. It will lock up in second gear thus cutting down on the slippage with results in lower operating temps.
I pull heavy so use both TowHaul and Exhaust Brake. When solo I just use the Exhaust Brake, turn it on before shifting to Drive.
Combo City/Country driveing is about 14 to 16, open expressway at 65 to 70 is close to 18 to 20, towing heavy average 10 to 10.5
92K miles and most of that towing and still on the OEM brake pads.

Spot on, locked converter means less heat.

[Grit_dog]

Run em both. Heck I do that driving empty (not in my 07 for those getting ready to jump on assuming the only truck I drive is the one in my sig).
All these new features have idiot proofed heavy towing for many. Read your owners manual and act accordingly.

[Michelle_S]

There is another feature in TowHaul mode with the Allison. It locks up the torque converter earlier. It will lock up in second gear thus cutting down on the slippage with results in lower operating temps.
I pull heavy so use both TowHaul and Exhaust Brake. When solo I just use the Exhaust Brake, turn it on before shifting to Drive.
Combo City/Country driveing is about 14 to 16, open expressway at 65 to 70 is close to 18 to 20, towing heavy average 10 to 10.5
92K miles and most of that towing and still on the OEM brake pads.

[larry_barnhart]

We have had the Allison on a 3500 dually 8.1 gas and now the 05 dually. I never saw any rpm difference at highway speeds using tow mode as I do on every tow. Once I forgot and noticed a difference climbing Blewitt pass and the trannie temp was almost 200 degrees. Hit the tow mode and slowly the trannie temp came down. Tow mode for me and the only good reason for not doing as I do is your truck is your truck.

chevman

[dave17352]

I have the same truck always use both. As others have said you still have the same gears TH just changes when it shifts.

[nevadanick]

I had a 2011 GMC and only used towhaul when in the mtns. I used the exhaust brake often but not always. Sometimes in towhaul and using the exhaust brake especially when i had my Dodge it would downshift to aggressively when all i wanted was to hold a speed so no tow haul unless i really wanted to slow down. Use it how you want to, get used to how it acts and if like me you will find that you will use all combinations to get the job done. You will not hurt the truck.

[Lynnmor]

Read the manual and use the buttons, and don't listen to nonsense.

Now about the fuel mileage, learn how to reset the readout at the beginning of a tow. Both of you are getting far less MPG than you think.

[gmcsmoke]

Cummins12V98 wrote:
Your neighbor does not have a clue!

When towing ALWAYS use TH and EB. I run them ALL the time, I hardly touch my brakes running solo.

this, read the manual

[DustyR]

Cummins12V98 wrote:
Your neighbor does not have a clue!

When towing ALWAYS use TH and EB. I run them ALL the time, I hardly touch my brakes running solo.

I have to agree with the above. The TH has two advantages, it extends the shifting points in the transmission and enables grade braking. TH enables the transmission to operate at lower temps.
While towing if you consider the EB as the primary brake for the vehicle it will make a lot more sense to use. On a commercial tractor and trailer (80,000) the EB is the primary brake, so why not utilize it on your RV/FW when towing?

[Cummins12V98]

Your neighbor does not have a clue!

When towing ALWAYS use TH and EB. I run them ALL the time, I hardly touch my brakes running solo.