[MattFL]

When towing in tow mode (exhaust brake mode "on") and the truck is happy to be in either of 2 gears, do you choose the taller or shorter gear? For exmple, say you're curising 60mph and a brief poke at the pedal causes a downshift, and then the truck is happy to remain in the lower gear as you continue to cruise at 60mph. Then speeding up 1 or 2 mph, then easing off the gas to slow back to 60mph causes an upshift, and now the truck is happy to stay in the taller gear. So there is the choice of 2 gears. Which is the better choice in regards to engine life?

With the gas motors my understanding is that the lower gear is better, it generates less heat. But I'm new to diesel.

 

[Duken4evr]

I don't like to lug it at 1,400 RPM under too significant a load, but 1,800 to 2,000 is prime economical towing RPMs. I would go with the gear that puts you there, speed and terrain permitting. 5th puts you there in that range around 60 mph, which is convenient :smile:

Unlike a gas engine, you do not want or need to buzz the diesel above 3,000 rpm for extended periods of time.

 

[Suns_PSD]

EGT 's are going to be lower in the lower gear. Coolant flow is better as well.
I'd probably just driver faster to remain in the higher gear though.

 

[CaryBosse]

EGT 's are going to be lower in the lower gear. Coolant flow is better as well.
I'd probably just driver faster to remain in the higher gear though.

Faster is better,>

 

[dmaxjr]

With the diesel I let it up shift and let the torque pull along ,towing or not. In stock form your egt's won't be an issue. Anything higher than 2500 rpm and you're wasting fuel on the diesel. 1700 to 2300 rpm is where my truck performs the best for towing my travel trailer. On the Steep grades (8%) that have switchbacks i will wind it up to 2600 to get up to speed after corners and let off a smidge to get into higher gear and keep rpm at 2200 rpm. On the foster sections(rare around here) 1700 rpm is all needed to keep load plodding along. Also getet great mileage this way.

 

[NWStever-1]

I'm new to the world of diesels. I've put on just over the 500 mile recommended break-in period so far. The 2.8L I4 diesel now has a bit better throttle response than when brand new but still nothing to be happy about. As for lugging the engine in a higher gear, I had a recent experience driving my truck over a pass where during ascent it held the higher gear it was in on the prior flat. The diesel alarmingly sounded like ball peen hammers banging away. I gave it a bit of throttle, the transmission down-shifted a gear and the noise stopped. I hope there was no latent damage done to the pistons during the hammering! My memory FWIW is that the rpm during the hammering was under 1500.

 

[DieselDrax]

That’s just a diesel being a diesel, no damage. This isn’t like a gas engine that’s pinging. Welcome to diesels!


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[Xwd]

EGT 's are going to be lower in the lower gear. Coolant flow is better as well.
I'd probably just driver faster to remain in the higher gear though.

This is what I see on our big (old -- Mack E350 engine) trucks at work as well. EGT's start to reach 900-1000, it's time to back out of it and grab a lower gear even if it's not lugging. EGT's are lower and the engine cools better if it's running at 1600 with some throttle to go versus one gear higher at 1200-1300 and wide-open throttle. Same concept applies here. Circulate the coolant faster, take some pressure out of the turbo, and everything works better while towing a heavy load.

 

[colt200]

This is what I see on our big (old -- Mack E350 engine) trucks at work as well. EGT's start to reach 900-1000, it's time to back out of it and grab a lower gear even if it's not lugging. EGT's are lower and the engine cools better if it's running at 1600 with some throttle to go versus one gear higher at 1200-1300 and wide-open throttle. Same concept applies here. Circulate the coolant faster, take some pressure out of the turbo, and everything works better while towing a heavy load.

I noticed this same thing with my old 3/4 ton duramax. With the little 2.8 i just go fast enough to stay in the top gear. In the flat lands I live in it is about 110-112 kph.

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