I know that the owners manual for my 98.5 and my 03 cummins both say not to let the engine idle for long periods of time, so how long is to long? I know there have been times that I have been on the road, have got tired and pulled over to take a nap in a rest area and have left the engine run to keep me warm/cool. I have always wondered how long I could let it run. If I slep for 3,4 or 5 hours is it going to hurt anything to stay running (other than MPG's)??? The 98.5 manual said that long periods of idle time could cause a carbon build up to form on the injector tips. Any thoughts or advice on this???? Thanks for the help!

 

It bugs me to hear an engine idle for longer than ten minutes, but that's because I'm neurotic. Anything over an hour can't be good, though.

Look for something that can give you a high idle. 1800 RPM makes injector coking and cylinder wash much less likely.

 

OK thanks for the info! I have the Bully Dog Triple Dog Power Pup that is supposed to have an option of an adjustable high idle through using the crusie control. I enable it with the Power Pup but I can't get it to work when I try to activate it.

Would the engine get hot in the summer running the A/C at 1800 RPM's for a long time?

 

I was told that anything over 10 minutes is bad. As the engine idles, the combustion temps inside the combustion chamber of the piston and cylinder head drop to a point where incomplete combustion starts to take place. This leaves behind raw, unburnt fuel that will make it's way past the piston rings and into the crank-case, resulting in fuel-diluted oil.

I'd have to go to the garage and look, but I'm thinking the OM for my '03 also put a 10-min time limit on idling.

 

Actually at an idle i would not run it past two minutes. but if I was going to sleep with the heat or a/c on i would set the brake and put a stick between my seat and acellarator pumping it up a cou[le hundred rpms. so my idle in my 7.3 ps is 750rpms , i would put it to 950rpms. then take a nap.
I drive a big truck and this is what our idle switch allows us to do. I run hard at work aprox 600 miles a day in oregon and washington state and on accasion have to nap for 15 to 60 minutes. truckerman

 

I know it's bad to idle but for years when it was cold I would leave the truck run for an hour or two while I did my barn chores so I would have someplace to warm up once in a while. Would I recommend doing this, no way but it hasn't seemed to hurt mine any other maybe I did have an injector foul up last year and this may have helped it along. I still leave my truck idle in the winter but now i have a high idle switch so i can set it up to 1100rpm's. But I did without it for 8 years.

The trick here is to not judge by time, so much as EGT's and water temp. It will take far longer for your engine temps to drop in warmer weather then it does in the bitter cold. If you watch your temp gauge in the winter when you idle you will see it fall below operating temp and that's when it's a problem. So however long that takes on that given day is how long it's ok to idle.

 

So as long as the engine temps stay in the optimum engine temp rang it can idle as long as i want????? Also how would I make or do they sell some type of an idle up kit? Like i said previously I can't seem to get that function to work using my Bully Dog. Also thanks to all that have answered back!

 

I thought on the newer trucks they would work using the Cruise control even without a controller. I may be wrong on this but I'm sure I've seen that in post someplace.

I found a guy in Idaho that builds a solenoid kit for high idle but the only site I ever knew him to hang out on is now off the net and gone so I don't know how to get a hold of him anymore.

 

load a smarty tune into it and then set it back to stock and you should have the high idle deal plus the 3 cylinder high idle feature...the only trick is finding someone with a smarty around you that will let you borrow it for like 10 minutes

 

The 3 cylinder shuffle is a factory flash that the dealer can do for you if you want that.