How long to idle to drop EGT< 300 degrees?

tomseeley · April 1, 2005

I just bought my first new used truck! A 2002 GMC Sierra 2500HD duramax/allison. Now if I could only find the "perfect" travel trailer to tow with it!

But first, I gotta learn how to drive it right. I know it's important to let the engine idle a little after long driving at high speeds on the highway. I know I'm supposed to let EGT get down below about 300 degrees. When I asked the mechanic who inspected the truck for me before I bought it he agreed that letting it idle "a few minutes" was a good idea. The owners manual didn't say anythying about it, though.

So what's the general rule of thumb? After I've been on the interstate at...ahem..."about 65 mph" for a few hours, how long should I let it idle once I pull into a parking lot, for example, before shutting it off entirely? I'm not looking to put a stopwatch on myself, but I do need some guidance. Is a minute enough? 2? 3? What? If I take 2-3 minutes at say 30-45 mph from the exit ramp to wherever I park, does that by itself do it?

Finally, one last question: is it a good idea for a newbie like me who wants to protect my $30K investment to install an EGT gauge?

Thx

Roofer · April 1, 2005

EGT guage if you want. It is good to have if you are towing or drag racing with a chip or programmer. It would also take the guessing out of the cool down period. As far as that goes, if it is warm out, I turn off the air conditioning or defroster and let it idle about 30 seconds to a minute. If you have to shut it down warm or just forget, don't worry, it's not gonna hurt anything. Once you learn it's noises, you'll know if you shut it down too early or not. Every truck is a tad different, but you will get to know yours in time.

Bart2500HD · April 1, 2005

Speaking of noises, a buddy of mine has a Dodge Cummins and when he shuts off the engine, it makes a chirping sound. Come to find out, when you shut off the Cummins, the engine stops turning before the accessories do and the chirping sound is from the belt squealing around the crankshaft pulley.

496 CUBIC INCHES · April 1, 2005

Unless your towing heavy,the EGTs should be down to safe levels in about 2-3 minutes. My mom has a Powerstroke and pulls a 13K lb fiver. When she gets off the freeway to get fuel or a food stop,the EGTs start dropping as soon as she exits the freeway. For the most part the EGTs will be in the safe zone after about 5 minutes.

IMO a good set of gauges is a must for a diesel truck that will be used for towing or hauling. Burning up a turbo isn't a cheap fix.

odoh · April 2, 2005

IMO gauges is one of the essential add-ons. Cool-down isn't a problem now as it once was w/older turbos. Yes, one can expect belt chirps on shutdown particularly if equipt w/any aux access load like a 2nd alternator. All in all, having an 02 myself, cant think of any real issues ~ drive it and watch EGTs when towing.