Idling time....how long!

[Jim Fulmer]

Are the 03's any different than the others or is it still the 20-30 Min rule.



Jim

 

[BHolm]

I think you can get away with 20 minutes. I personally try not to allow extended idling at all. When I bought a new Mack truck in '01 the dealer told me to always idle it up while sitting. The low rpm causes unburnt fuel to get through and produces a varnish in the exhaust that will kill the turbo. The tolerances on the new engines are so tight that this becomes a problem. He told me that Mack had denied warranty claims based on this build up and not following factory reccomendations. I think my D-max says 20 minutes in the owners manual, I haven't looked for it in the Dodge manual yet.

 

[Vaughn MacKenzie]

It makes a big difference what the weather is and if your engine is at operating temp to begin with or not.



If you have a cold engine, no matter the weather I wouldn't go more than 5-10 minutes max. A hot engine on a warm day you could probably do an hour easy. But why let it run and waste fuel? Just shut it off because it's not going to hurt it to stop it and restart it, a lot less than just letting it run for hours.



I have a 5-10 minute rule. . . if my stop will take longer than that I shut 'er off.



Vaughn

 

[dPierce]

Don't forget to let your rigs idle before shutdown, there is a chart in the owner's manual that shows how long to let it idle based on various load and speed conditions.



I run mine empty down the Interstate a lot, so I usually let her run for about 3 to 5 minutes to let the turbo slow down.



Cold starts: When the temp is say between 0 and 30 degrees F, how long should I let the '03 "warm-up"/idle before moving. I've heard that just a few minutes is better that 10 to 15, basically the engine will take forever to warm-up at idle, it's better to idle for a few and then get her down the road with light to moderate throttle until she's in the normal operating temp range... ... any thoughts???????????

 

[BHolm]

The turbo slows down right away. The turbo does need a little time to cool though, saves on the bearings. Running empty on the highway shouldn't require much, if any, cool down. Check the chart in the manual. Normally you have a short low speed drive when you come off of the highway, that is probably plenty. Of course the best thing to do is add a pyrometer to measure EGTs. It is a good indicator of how long you should cool down.



If you are not pulling or hauling from dead cold I think a very short idle is reccomended. It will not warm up until you burn some fuel, your not burning any at idle. Probably a good idea to idle for a couple minutes before setting off with a big load though.

 

[Jim Fulmer]

I need to clearify, the person in question was wanting to be able to pull over and idle the truck while he slept in it for extended periods to save hotels costs or be hot(now) or cold in the winter, I had already told him no.



Thanks, Jim

 

[CATCRACKER]

sure he can! just idle it up to about 1200 rpms with the ac on lay out the fold out floor lay down his bed and go to sleep. if the big trucks do it he can do it. it is not the best for the motor but even doing this the motor will last longer than he wants to keep it. the ac on an the motor idled up this is enough of a load to keep these engines burning all of the fuel metered out. now in severe cold conditons just get a hotel room. common sense of course applies here if it is -15 degrees get out of the cold!!! the electronic motors dont dump excess fuel.



these fold out floors make a great bed with the right foam on top. trust me. and bye the time you wake up in the morning you will have frost on your nose.

 

[Parshal]

Originally posted by CATCRACKER

the ac on an the motor idled up this is enough of a load to keep these engines burning all of the fuel metered out.

I had a computer plugged in my ECU the other day and watched the RPM's change when i turned on the AC. It was 750 without AC and 756 or 759 with the AC on. Not much.

 

[Jim Fulmer]

These fold out floors make a great bed with the right foam on top.



Would you enlighten me on them so I can pass it on, and does anyone make a high Idler kit fro the 03' yet.



Jim

 

[dPierce]

A little AC compressor taxing the big diesel????? This isn't 4 banger gasser, the Cummins does even blink when the AC comes on. My welder on the other hand, kicks the RPMs up a hundred or so...

 

[CATCRACKER]

my tac shows a larger drop than that. when you have it reved up to 1200rpms watch how much it drops alot more than 10rpms

 

[thejeepdude]

The RPM drop when the AC is turned on is not a good indicator of extra load put on the engine. At idle, the ECM controls the idle speed. If it didn't, you would stall when you put the transmission in drive. The ECM adds more fuel as the load is increased, this is why the RPMs might have only dropped 10 revs or so at idle, but drop more while off-idle, where the fuel stays the same as long as you didn't move the throttle, and you can more accurately see the effect of the A/C. That said, it's still pretty worthless to measure it this way. If you really wanted an accurate measure of how much more fuel it takes to keep the A/C going, you would need a fuel GPM reading. This increase in fuel could theoretically be computed into a thermal value and you could get an idea of how much more heat is generated at idle with the A/C on... or you could just look at your temperature gauge. I leave my truck idling for extended periods all the time. In these 100+ degree summers, I like the A/C running while I'm in the store shopping. I've left my truck running for 3 days straight before, with no adverse effects. When the temps outside are warm enough that an idling CTD will be hot enough to cycle the thermostat (190), there's not going to be any problems associated with idling for long periods. When it's colder, a high-idler should be used to keep the temps up, and even then it's a wise idea not to let it run for too long. But then again, I don't need the A/C running while I'm in the store in the winter, either.