High Idle w/ Engine Fan on for 10 hours..????

I have seen many rigs have an engine melt down due to fan belt coming off idling, which didn't affect the gear driven water pump. They all need a little air from time to time. My fan will cycle with the A/C long before the engine needs it still yet serves the purpose.

 

High idle has nothing to do with emissions, you need heat in the engine, especially in cold weather. If you look at a truck in cold weather and there's vapor coming out of the exhaust, it's because it's not running hot enough and is actually having condensation inside the engine.

 

I don't know about easily, it has to be a very hot day (100 plus) and you have to have the engine under some load to produce heat. The mass that is being driven (crank, pistons and trans) isn't enough to produce the heat that is needed to be carried off from idling or high idle. This is what is puzzling me, the cooling efficiencies of the radiator and water pump have to be more than enough to keep things cool under load let alone at idle with no load unless there is an issue. When the engine is under load, that is where heat is produced, like going up a hill with a full load.

 

I sleep with earplugs in fairly regularly. It helps a lot but I get what you are saying,

 

How do you find these sections of the truck stop where no one is idling? When you pull in the lot and your truck is running how can you tell which trucks are running or not? Do you shut your truck off and listen for the quiet spot then go park there? Highly unlikely. There is no quiet spot at any truckstop. Except maybe your own shower room at 3:00am

 

It's Zen. You are supposed to know this. Until cupcake only parking signs are installed you are SOL.

 

I keep my fan on and idle at least at 1000 rpm as cat recommends. The only time I idle is if I'm on a pull off because the truck stops were full. Keeps the carbon from building up and keeps the cylinder pressures higher which keeps from washing out the cylinders and removing the cross hatch marks on the liners that help hold oil along the sleeves. You should never idle an engine for long periods of time at low rpm. That's one reason you'll see trucks with less than a couple hundred thousand miles with tons of blow by and low power. Do things right and your equipment will last a long time. This c15's going on 1.3 million miles and runs strong with no excessive blow by and no power loss. No damage to the factory turbo, valves, or any internal components from carbon build up from excessive idling. Another good thing to make sure is to never lug the engine. But to answer your question yes it is fine to leave the fan on overnight just keep the rpm's to what the manufacturer recommends and make sure your coolant temp is back up around 180 before you start pulling hard.

 

Yep, the key word is - "believe".

 

Old thread but:

An engine running cooler than specified, (typically less than 190 degrees F) will affect EGR and fuel injection rates which will affect NOx levels that the SCR system has to convert.

Under low idle the engine doesn't reach full operating temperature and the EGT is low so soot will accumulate in the particulate filter and more soot reaches the filter. While low EGTs and idle time are also hard on the turbo, especially when the ideal is 350F or higher EGT's , the reason companies want you to use high idle is so that they don't need to replace the one boxes, or deal with def injector failures as often. Also parked regens will be more common and those burn a lot of fuel.

As many manufactures parked regen won't happen unless the HVAC is off so parked regens won't happen with typical sleeping with HVAC on and that's were you end up with derates etc....

Over cooling with the fan switch, or not enough load (low idle for hours), are the primary reasons for emissions systems problems like regens, plugged def doser etc... with the exception of cases where the engines have a lot of blow by or other mechanical problems and upstream leaks that cause ash buildup.

In passenger cars they have similar issues which they solved by making the temperature gauge sit in the "normal" range from ~190-235F. But us truck drivers still get the fan switch and real temps. We just need to remember that things have changed in the past 50 years.

In EGR and newer emissions trucks need to run hot, which low idle simply doesn't provide.