I am new to the world of diesels. The owner’s manual for my 2002 Cummins ISB warns to idle the engine 3 to 5 minutes before shutting it down after a full load operation to allow a proper cool down period for engine components, especially the turbocharger. How do you diesel veterans handle the idle/cool down period when stopping for fuel after running at freeway speed for hours?

In the seminars that I've attended by Cummins, they tell us that an idle period isn't necessary. The engine will cool enough during the freeway exit/entrance to the fuel station, etc. I don't know many fuel stops that don't take a couple of minutes to get to from the time I knock off the cruise control until I shutdown at the pump.

Robb & Sue Steinheider
Duncan the Dalmation
03 Ultimate Advantage
02 Saturn L100 Toad
Cummins ISC 350hp

Rnbj, welcome to iRV2.

Robb is correct, the short drive at slower speeds is adequate.

If I was pulling directly into a rest stop, I would let my engine idle for a minute or two.

I allow this extra time but calculate it on all factors such as time at stop light, pulling up to the pump, etc. I give it at least 3 minutes.

Thank you all for your input.
rnbj

quote:

The owner’s manual for my 2002 Cummins ISB warns to idle the engine 3 to 5 minutes before shutting it down after a full load operation

The above colored part of the sentence is the qualifier here. Just driving down the highway/freeway is not a full load application. If coming off the road after a long hill or pulling off the side for a brake check after a hill where you are stressing the engine and turbo is where the cool down is required..

my 2 cents...

Let’s assume that while the engine is running oil is being circulated throughout your engine and also the Turbo which is driven by exhaust gases, (the highest temperature in this whole equation.) Once the engine is turned off no longer is the oil circulated through the engine as well as the turbo shaft/bearings which allows the stagnant oil to bake on the still shaft. If the engine was at it’s normal operating temperature and you don’t try and help it cool down especially for the turbo one can be asking for problems such as early bearing or seal failures. The point is you won’t see a failure immediately but chances are you will see them sooner than one that follows what is recommended. Most of use don’t climb mountains everyday nor do we pull 10,000 pounds on a regular basis and even when that does occur the engine temp goes up a modest amount. Fact is most turbo failures are caused by excessive heat preventing proper lubrication and this is enhanced by not letting the turbo cool down as much as possible, especially if you plan on shutting down.

I usually idle the engine for a few minutes before fueling. I figure that a few minutes of idling is not that expensive in comparison to a new turbocharger. I do the same thing with my wife's Mini Cooper. I let the engine idle for a minute or two to keep the supercharger oiled while it cools down. Fuel is cheaper than replacing a charger.

About the only time I allow for a few minutes of cool down time is at a Rest Stop. Often, they are right on the freeway and you have to slow/stop fast to enter. I usually let it cool down for a few minutes in this situation.

Every post here has unknowingly reinforced the importance of a EGT gauge. The upper safe operating temperature is 1,300*F pre-turbo measurement. Most diesel engine repair centers recommend waiting until the turbo temperature is under 350*F before shut-down for longest turbo life.
Don't take my word however; stop in and ask the guys who rebuild and repair diesel engines every day.

Ray,IN

OK, I Googled “EGT” and I see Exhaust Temperature Gauges listed from $99 to $499++. Do you have any recommendations for make and model numbers? Would you say that installation should be left up to a professional? After reading some “simple” installation instructions, and reading there is a possibility of getting metal shavings in the turbine housing, I have my doubts/fears about doing the job myself.

Thanks for your post.
rnbj

quote:

Originally posted by rnbj:
Ray,IN

OK, I Googled “EGT” and I see Exhaust Temperature Gauges listed from $99 to $499++. Do you have any recommendations for make and model numbers? Would you say that installation should be left up to a professional? After reading some “simple” installation instructions, and reading there is a possibility of getting metal shavings in the turbine housing, I have my doubts/fears about doing the job myself.

Thanks for your post.
rnbj

As you discovered, you can spend a lot of money for gauges that basicly perform the same function. I chose to have a Cummins Authorized Repair Center install the gauges and pyrometer in my 1996 Dodge CTD for the reasons you mention.
Recommendations? It's been 10 years since buying my gauges, what I know is practically useless today. I can't remember the brand I bought, but it was two digital gauges in one 2" round housing, EGT and transmission temperature (owner selectable). I deleted my bookmarks pertaining to my old Dodge CTD when I sold it in 2005, so I can't help my memory that way. I do remember Scheid Diesel did the work and sold the gauges-HEY, Isspro gauges is the brand, the name just popped out of the cobwebs . You may wish to browse dodgeram.org to expand your investigation of gauges and engine protection, as well as Scheid Diesel's website.