Idle RPM vs temperature

[HDN]

This is an engine question in general, although any information regarding the Cat 3116 specifically is welcome.

The TM for my truck says that the engine should be at an operating temperature of 160 degrees before applying a heavy load. On a 40 degree day, this takes a half-hour at 1200 RPM to achieve. So I'm wondering:

1) Is this a typical warmup time for an engine? On the older gasser army trucks I've driven in the past, i let the engine idle just for about 5 minutes to let the oil circulate and the pistons expand a little bit before going down the road.

2) 1200 RPM is allowed for my truck's warmup even though idle is about 800 RPM. Is there any harm idling at 1500 or 1800 RPM at idle before reaching operating temperature since no load is being applied? This is important to me because I currently need to manually inflate the tires, which takes me about 30 minutes to do at 1100 RPM.

 

[Jgreg49]

Diesel engines create very little heat when not under load. I'll usually start mine up and let it idle for a couple minutes before I idle it up. I'll usually set it around 1500-1800 when I do idle it up.

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[162tcat]

OTR truckers start the truck, finish their pre trip (5 min) and hit the road fully loaded before the temp gauge even moves. Those trucks go a half million miles or more without issue. Start your truck, build air and go. It will be fine. Don’t overthink it.


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[HDN]

I've been doing some more reading about the warmup and it seems like a good idea to idle the truck for about five minutes before increasing engine speed, mainly because the turbocharger needs to have proper oil circulation to prevent damage at higher speeds. I saw a dashboard plate on an M35A2 recommending a 5-minute idle for this reason.

 

[162tcat]

It doesn’t take 5 min for the turbo to get oil. 10 seconds maybe. You’ll do more damage by letting a diesel low idle cold than letting it high idle. Seriously, start and bump the idle up if cold. You think the young military guys treated her gently? Nope, it’s uncles truck! Start her up and drive it hard!


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[montaillou]

You think the young military guys treated her gently?

Most of them didn't have to fix it if it broke, and it wasn't their money in the truck.

 

[162tcat]

Most of them didn't have to fix it if it broke, and it wasn't their money in the truck.

You’ll cause more issues letting it idle cold. Computer controlled diesels high idle automatically when cold. Research wet stacking. If your concerned about longevity (of a rig that you’ll likely put less that 10k miles on in your life) then idle it up when cold and/or plug it in so it warms up quicker. Diesel standby generators go from cold with no lubrication to full load almost instantly and you don’t hear about those blowing up very often.

Seriously, don’t reinvent the wheel. Just enjoy the truck.


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[montaillou]

Seriously, don’t reinvent the wheel. Just enjoy the truck.

I'm not reinventing anything, my truck has a plate on the dash panel that says to idle it 5 min before going anywhere and 5 min after I stop.
Reading about wet stacking, perhaps I should pay attention to the exhaust, but I really only notice black smoke when I first start it up - that goes away very quickly. However, I've really noticed >my< truck doesn't achieve full speed on the hwy until about 10-20 min of travel. Sure, leaving the engine to idle for 20 min could be a bad thing, but I idle for 5 then I head out. Also, my truck takes a couple min to fill the air tanks anyways, I'm sure as hell not going anywhere while that air buzzer is sounding!