What are the ups and downs of a vehicle running at idle for a shorter period of time 20- 30 mins? People say its better to leave them run, but what about cylinder wash?

 

I figure if its going to be more than 15mins just shut it off. dont have any facts to back it up sorry.

 

not a wise ideal to leave the truck idling that long i would agree with monster anything longer than 10-15 mins shut it off.

 

I thought they could idle all day it the temps were at the normal 180*? Isn't that why they and semi's idle up their truck?

 

But the temps do not stay up when idleing unless you have a means to put a load on the engine (exhaust brake) or have a high idle.

The myth that diesels can idle all day long is just that - a myth.

If its any longer than 10 or 15 minutes - shut it down. This is especially impiortant in the cold an if you have an automatic with a stock torque converter (they dont circulate the tranny fluid in park).

 

ive heard about the cylinder wash, but i also have heard from other people who have high idle who leave their trucks on for extended periods of time, from what i heard the with the higher idle the engine is able to burn a higher % of the fuel and cylinder wash is not a problem

 

Yes, the problem is that the Cummins will not make enough heat when it is idleing and as I said before you need an exhaust brake to put a load on the engine or a high idle switch. Both of these devices keep the combustion temperatures up and will virtually eliminate problems due to extended idling...

 

Here is a toy I'm working on... A high idle kicker for colder morning and get the coolant temp above 175*F rapidily...

Between 3 Cylinder high idle and a exhaust brake I can hit 800-850*F in EGT...

http://mopar.mopar1973man.com/2002%2.../high-idle.htm
(Towards the bottom of the page)...