So diesels dont like to sit....

When I was OTR and idled I figured my Detroit Diesel used 0.7 gph. That's what my truck worked out to. We would bump the idle up to 1,000 rpm to keep the oil pressure at 45#. CATs and Cummins were about the same. Company always claimed a 1 gph at idle but that was high. The company had a reduced idle policy and you had drivers that would just start an engine and take off. After 2 or 300,000 they would burn blue. Low idle is good but warm oil in an engine is better than cold oil in the pan.

Oil fired bunk warmers used a pint per hour but the heater discharge was very hot and about floor level in the bunk. If your blanket fell off the bed it would get very hot and I was concerned it might set the blanket on fire.

APU's are nice but the added weight, cost and maintenance made them not practical for my fleets. Easier to tell the driver not to idle and freeze or roast. Heaven knows how easy it is to get your rest while sweating in bed.

I'd be more worried about seals drying out that the engine itself from non use.

We plug the coach in and allow the engine block heater to hold the Cummins at temp. then when we want to go, we go.

I have 148K on my 01. Idling washed down the cylinder walls with fuel. If you bump up the idle speed you will be fine but unless you are driving an OTR without an APU you will not really idle any longer after stopping.

koda55 wrote:
When I was an otr driver I would idle my engine over night to keep warm in the winter and cool in the summer. I would bump the idle up to 1000 rpm. I never had any problems with my engines. Many drivers never shut their engines off from the time they leave home until they come off the road for their time off. Of course there may be differences in big rig engines and RV diesel engines.

Just out of curiosity, how much fuel did you burn idling for 8 hours to run the heat or air? I always wondered if there wouldn't be a way to mount a 4000 watt diesel generator on big rigs to provide A/C and heat to the cab. Seems like it would burn a whole lot less fuel than the main engine.

When I was an otr driver I would idle my engine over night to keep warm in the winter and cool in the summer. I would bump the idle up to 1000 rpm. I never had any problems with my engines. Many drivers never shut their engines off from the time they leave home until they come off the road for their time off. Of course there may be differences in big rig engines and RV diesel engines.

Advice from both Caterpillar and Cummins:

Cold start: Idle long enough to build air pressure/do your walk around. Then, you are good to go IF light throttle. So driving out of CG, city driving is good.

If you are parked at an freeway entrance ramp, after 2 minutes or so, go to high idle (usually with cruise control) until coolant temperature gauge is to 150 degrees F IF you need to really get into it to enter the freeway.

Cool down: Most do WAY too much idling for this. Sure, if you have just crested a mountain and pull into a rest area, let it idle for 3-4 minutes to cool down.

But, if you have driven slowly into the CG and then to your site, you are good to shut it off IMMEDIATELY. Basically you want several minutes with turbo NOT working. And in slow driving and in CG driving, you are not in the turbo.

How long is excessive idling?

What I usually do is just when it's time to empty the holding tanks, I'll start the engine so that air system will build up pressure. The slides are already in, TV off, cable coiled up, antenna down if used, door mat put away.

While I'm emptying the tanks and turning off the water and reeling up the hose, I'll here the first 'sneeze' of the system. At that time, I'll run inside the coach and hit the 'travel' button so the coach will either retract the level legs or come up to ride height if I've leveled on the airbags.

I'll go back out and finish wrapping up the wet bay. I'll come back inside the coach, throw away my plastic gloves, wash my hands, grab a bottle water to keep with me at the driver area and then I'm almost ready to pull out. I step back outside and check the toad lighting while my co-pilot flips the turning signal lever and applies the brakes, then we are ready to roll.

So, I'm thinking maybe not more than 12-15 minutes idling. Is that too much?

MM.

OK, I misunderstood the earlier posts. It's not good to JUST idle an engine. I never do that. I usually idle the recommended time and then drive it, always getting up to operating temperature. If I've been pulling hard, I also idle it a little to let the turbo cool down. Thanks for all the info.

Diesels will not get really warm at an idle, you have to take them on the road. Therefore, either take it out and run it so everything gets to normal operating temps, or don't start it. BTW, the ISC is an 8.3L engine.

Here is a video that will show what can happen with excessive idle time on a 6.7 Cummins.
6.7 Cummins long idle time