Cool down

[Ranger354]

Just put my second tank of diesel in and was wondering if you guys allow your engine to idle a few minutes after a long run. I know that some diesel require 5 minutes of idle time after they have been run hard. Any comments?

[JEBar]

GM must not worry about letting her cool down because they don't provide a gauge to monitor EGT's nor do they mention it in (my) owner's manual....the only way you will know for sure how long to let her idle is to install a gauge...from what I read most folks shut down at 300 to 400 degrees (some pre and some post turbo) :cool:

[IndigoDually]

It really depends upon what you are doing. If I am pulling a trailer then I definitely allow some time (up to 5 min) depending upon how I was driving. I temps are up above normal and the trans is a little warmer that usuaul then I allow idle time. Just driving around empty the time of light throttle application along with the fact that I alwaws back my trucks in when I park is sufficient time. Cruising around a parking lot looking for a space is sufficient cooldown time. If I came off a highwat with a heavy load and stopped right away at a gas station, I would allow some time.

The turbo on these trucks is also liquid cooled which helps to prevent some of the oil "coking" Which is the major reason to idle turbo charged motors after use. 6.5's and many others are not so when a relatively hot turbo motor is shut down the turbo housing is holding a lot of heat and bakes the oil in it (turns to sludge) this in turn restricts the oil passage and leads to a failed turbo due to a lack of lubrication. Remember the turbo spins at high rpm's 20,000+ (I think) so oil is very important in it's life cycle.

There is always the other side of the coin regarding too much idling, this is where a fast idle would come in handy.

John

[Russ Denman]

I carry both sets of keys when running hard, lock the doors and leave the truck idling while taking care of business before refueling. This gives it a good 5 to 15 minutes to cooldown.

The other day a coverted bus left his engine running while refueling. I don't know if this is advisable or legal.

[Amianthus]

It's better to do it and not need it, than to need it and not do it. Just a little bit helps. Too much can be bad.

As far as refueling goes, adviseable? Whatever floats your boat. If you're filling around diesel only. Diesel fuel's flashpoint is substantially higher than gas so it won't ignite off of hot components. However gasoline can. Theoreticly, if the vapors being displaced while someone is filling their gas tank collect around your catalytic converter, they can ignite. That's bad. Another reason to kill off gassers.

As far as legality goes, it depends on the jurisdiction. But it probably would be illegal. Of course, a fart in the wind is illegal in some places (Kommiefornia).

[tmg115]

here in texas it IS illegal to leave your truck running! WTF??? who comes up with these stupid laws?

[IndigoDually]

There are signs posted at the pumps saying it is illegal in NJ. It is also hazardous to refill gasoline cans in the bed of your truck due to the possibility of static electricity making a spark and igniting the vapors. This is more of a chance when filling a plastic can in the bed of a truck with a plastic bed liner.

The attendant usuaully has a few words for me when I am filling diesel cans on the back of my truck. My answer to him is to get a dictionary and look up the words"Flammable" and "Combustable", figure out the difference and get back to me. :D

The red lights and the "Fire Chief" plates should tell him that I have a clue with what I am doing.

John

[DURA-MAX3]

After running any turbo charged engine for long periods of time or while working the engine hard you should let it cool down to keep from cooking the oil that is left in the turbo bearing oiler. over long periods of time of
oil being cooked, it can restrict the flow of oil throuh the turbo oil line...