Hi. I’m still pretty new to diesel ownership. Is it bad to let a diesel idle long? I see my 2019 6.7 tracks idle time. There must be a reason for that. I remember when big diesel rigs used to idle all night long. I have heard some say idling modern diesel engines is not good yet others say you should let a diesel warm up a while before putting it under any load. Can someone help me understand the pros & cons of extended idle time on a 6.7? Thanks.

 

Depends - general guide as it applies to your model year truck.

Idling other than for a minute or two on a cold start, and a minute or two for cool down, does nothing else than consume fuel. So if you need to idle to stay warm, stay cold, keep an inverter going, etc, then you idle. But if you are idling because you don't want to start and stop the truck, you are not helping the truck and should opt to shut it off.

Personally, I think a couple of minutes warmup and some sort of cool down period is more beneficial than not. If you are cruising light loads, shutting off 30 seconds or so after stopping would be fine. But if you are trailering and under load, and see that rest stop and are like I need to stop now, idling for a couple of minutes to let temps stabilize, and the extra under hood heat to be rejected, I think lends itself to longer turbo/engine life/component life.

Now to be specific, earlier model 2011 + engines were prone to plugging EGR coolers so excessive idling, low speed -low load around town, plowing, all contributed to earlier EGR cooler replacement due to plugging. Revisions in controls, calibration, the EGR and secondary cooler loops, have made EGR cooler plugging almost non-existent on later model trucks, yours for certain.

 

I am also new to diesels and what is mentioned above is what I have come to understand. Now that it's gotten colder I will generally crank my truck with the FOB as I am walking out the door to the truck. I'll unplug the engine block heater (if plugged in), then get in, insert the key and turn it "ON", put my seat belt on, get my badge for work and organize anything I may have carried into the truck, then put her in reverse and get going. I don't drive it hard until it's up to operating temps, however, that doesn't usually happen on my short drives to work. If it's summer time I just wait until I get in the truck to crank it with the key and then follow the same routine. This usually gives the truck a little time to start circulating fluids and makes getting started pretty easy. When I finish a drive I do watch my EGT temps (via Banks iDash) and wait until EGT 1 is back down to 400 F or a little under before shutting the truck off. (And if you don't have a way to monitor EGT temps, or Regens, I would suggest picking up a monitoring device so you can).

I do not let the truck sit and idle beyond this. I avoid drive throughs and will just go inside and sit and eat or order it to go. I don't let the truck idle when fueling up, etc... As mentioned above, when towing I will let the truck idle for as long as it takes to get the EGT temps back to "normal" temperatures before shutting it off. This usually doesn't take very long though.

I remember hearing that it was good to just let diesels run and idle, but it seems that was with pre-emisions diesels. With all the emissions that are on these trucks now it seems they are better to either run hot or not at all, and idling them won't keep them "hot enough." I did wire in a 20k OHM resistor and connected it to an up fitter switch so now if I ever find myself in a situation where I have to idle (ie: keeping the truck on because it's so hot and we have to sit in the truck) I will switch the high idle on and it will idle at 1200 RPM's instead of 600. This helps, but I would still choose not to needlessly idle it if I can.

Also, I am using additives that are supposed to help with a more complete fuel combustion and cut down on the amount of soot created, however, just search around... additives are a big talking point here. You just have to do what makes you more comfortable here! LOL

 

Ford just keeps adding stuff that requires you idle.
They were kind enough to put in the Wifi. Great connect with my laptop and have a Zoom conference calls with the Architect when I have questions about blueprints. Problem is Wifi needs the the truck power on. And I get tired of it going into power save move and shutting down in the middle of a Zoom call.

And with the 2000 watt inverters coming in the 23 models. Yep. going to see people letting the truck run for hours to generate power.

So either Ford doesn't see a big problem with idling, or they are staffing up their dealer mechanics again.

Now when I ran oil up in North Dakota, We never shut the diesel engines down. It was too hard to get them started again if you shut them off in -25° temps. Pull into the railyard or pipeline and have a 6 hour wait until your turn to unload. Leave the truck idle and take a nap.

BTW. When you idle. The excess fuel passes thru your fuel system and gets heated up. The warm fuel is returned to your fuel tank and warm all the fuel in your tank. Thus preventing gelling. Hence if you are worried about cold temps gelling your fuel. Just let the truck idle

 

Normally started around 0500, driven to lz idling all day long, drive to closest airport to fill the tanks with jet a, driven back to hotel and shut off. Normal day less than 30 miles in 14+ hours for several weeks then driven to next job. Sometimes hundreds of miles sometimes thousands.
never had an emissions problem.
we had 6, from 2012's through 2017's when I worked there

 

I believe you don't want to idle a cold engine for long periods (with long periods not defined), but I've never had a problem with idling when the engine is hot. Ford also made a change with the regen process and that it originally regened using the driver's side pistons (4 pistons), but later changed it to all 8 pistons which I believe increased the regen temperature of the EGR cooler and valve which probably helped burn off some carbon. My truck has over 250k miles and I've yet had a problem with the EGR valve/cooler plugging up. I idle it just like I did my 05 6.0PSD in which the EGR valve would plug up every 80k miles.

 

Thanks for that info, about the change to all 8 cylinders instead of just the 4... Was it with the start of the Alumina Dutys, 17 plus or the 20 plus that went to all 8?

 

It was a change to fix the jackhammer problem that affected some 11-14 trucks and mostly 15-16 model year trucks that this jackhammer noise/vibration occurred during the early stage of the regen process. Ford had a TSB to address this problem by replacing the valves on the drivers side engine bank and reflash the pcm to change the regen strategy to all cylinders. I believe this TSB was implemented in 2016.

Regen issues, jackhammering. - Page 3 - Ford Truck Enthusiasts Forums (ford-trucks.com)

 

You can install the high idle mode and just throw a switch to reside your idle speed to a number that has the engine running better (less soot and less fuel cylinder washing)

 

My truck probably idles for about an hour a day waiting to pick my kids up from school and I’ve had no issues…(knock on wood). I was worried about the soot collecting but I’ve been using Schaeffer’s Carbon Treat fuel additive and it makes me feel better. Honestly, not sure how well it works but Schaeffer’s is usually a solid brand. I’ve wondered about the tracking of idle hours too and I’m still not sure why it would matter enough to monitor it if it wasn’t a potential issue.

 

Appreciate the link...

I bought my truck new and never had a problem with the jack hammer during regen... thanks for posting up.

 

While an idling diesel doesn't consume all that much fuel, diesel is still expensive!
I don't idle my truck to warm it up. I start it and within 30 seconds pull out of the garage and go. But I'm easy on the accelerator for the first few miles.
I do idle my truck to cool it down, using engine oil temperature as a guide.

I was hoping for no more than 10% of engine hours as idling, but that's not going to happen. More like 15%. Connecting/disconnecting a trailer takes time. The truck is fairly aggressive at assigning idle time. Sit at a light with your foot on the brake for a minute and that's one minute of idle time.

 

Two things with idling a modern diesel. DPF plugging, and fuel in oil. High idle time motors have more frequent regens, which puts more fuel in the oil. Aside from that, no difference other than a little more wear than one with high miles and low idle.

Case in point, my new Kubota L4060 has DPF and if I idle it, or use it without setting the RPM up to 1500 when tractoring around, the DPF soots up faster than if I run it at PTO speeds. I found it is also clogging up the EGR and setting codes. Diesels like being worked hard, a load on them is much better than just freewheeling. Other than a minute to cool down the turbo, I don't let mine idle much.

Different story with non emissions diesels, let them idle forever, nothing to clog up with soot, damned emissions schiznit.

 

I don't worry about idle time. Do the high idle mod (many threads here). Don't idle if you don't need to, but if you need to it's fine. Better if it idles around 1200 rpm, keeps the fuel burning and not washing the cylinders. If you do idle, follow severe duty maintenance schedule. As stated, it may regen more frequently.

 

Thanks to all that have responded. This is all very useful info. I’ve also learned there might be a concern I didn’t consider. I tow a 15,000 lb 5th wheel with my F-350, 6.7. I didn’t know I should idle a while to cool things down when stopping at a rest stop or after unhitching. Is there a rule of thumb to follow as to how long to idle when the engine is hot from towing?