I read in the diesel supplement to the 6.4L that I shouldn't let the truck idle excessively. The very next page says the PCM has a cold weather idle function that will bump up RPMs after 130 seconds to avoid/minimize potential wetstacking. But the next paragraph says I need the high idle mod if I want to let the truck warm up in the AM.

My question is: How long can I safely let a bone stock 2008 6.4L idle in the morning without damage? The RPMs come up to 1000 RPM after it has been running for a minute or two. I hate getting in a cold truck almost as much as I hate scrapping ice off the windshield but this truck needs to last me!

 

You are right, it's a loaded question.

I don't think there is anything wrong with 10-20 minutes of idle. Elevated idle for cold weather conditions is automatic, you will see for yourself. The high idle modification is easy and you should go to the 6.4 tech folder here and do it. I will idle high when I fill up with fuel, grab lunch to go, etc...

As you use your truck you will find that "making oil" is an issue. My truck does not make oil, at least very little. This is dilution of the engine oil with diesel fuel. Your truck may or may not but you won't know until you get 10-20,000 miles on it. Idling can cause making oil though it is unlikely.

Idling for long periods of time mainly is a concern for the exhaust gas recirculation system and the exhaust gas recirculation valve and also the exhaust gas recirc. coolers. Usually referred to as EGR, EGR valve, and EGR coolers. Lots of idle could cause contaminant build up on/in these components. As long as your engine is hot and gets used hard it should be ok.

The other concern is the turbo system. If you are running your engine under severe load and the temps are very hot you should idle before shut down to let things cool off.

It's a conundrum. Don't idle for 6 hours/day but idle is good for cool down and initial warm up. After the engine is hot, elevated idle is better than low idle.

I know I am long winded but I am trying to be thorough as you stated that you are new to the diesel world, and specifically the 6.4, which is a new game in itself.

 

Winded?

That's an excellent answer - thank you!!

 

nothing to add here! I don't make oil either, less idleing is the best policy unless you do the high idle mod.