Attention: TDR Forum Junkies 
For over a year since I bought my '08 C&C I've wondered if it was okay to shutdown when egt was high because the engine was in the regeneration mode immediately prior to placing the shifter in Park. The owner's manual provides the standard boiler plate information that has probably been in every owner's manual since the old 12 valves were installed in the Gen I trucks but there is no mention whatsoever of shutting down when the engine was in regen mode. When I shift to Park regen is terminated, probably happens when the clutch pedal on a G-56 truck is depressed as well, but EGT will be up around 600* - 800* when regen is terminated. I've allowed the truck to idle as long as possibly ten minutes in hot summer weather before egt decayed below 400* and I felt safe in shutting it down.
Another thread today got me thinking about the question again so I finally took the initiative to call Cummins, Inc. and ask. It took a while but I finally worked my way through the system and spoke with someone familiar with the ISB6. 7 who could provide good answers to my question.
Here's the answer from Cummins:
Hot shutdowns at egt up to 600* are acceptable and not likely to cause harm.
The turbocharger used on the ISB6. 7 has a higher heat tolerance than previous generation turbos because of the more restrictive emissions requirements on the 6. 7 and the need for regeneration of the emissions components.
Also, because the ISB6. 7 engine turbo is watercooled, it can tolerate hot shutdowns better. Our old TDR guidelines of allowing egt to decay to a maximum temp of 350* is no longer applicable.
The Cummins rep I spoke with today told me that a short cool down delay is desirable following full load, full power operation such as heavy towing at highway speeds but he said it is not harmful to shut down with egt as high as 600*. EGT can be this high if the engine was in the regen mode immediately before shifting to Park position.
I think Robert Patton wrote a similar opinion in a previous issue of TDR magazine where, IIRC, he stated that he routinely drives his Ram pickup w/ISB6. 7 engine like a gas engine. I think Robert said he uses no idle delay for cool down at all.
Cummins, Inc. is the only major American corporation I've ever tried to contact about their products and found that their employees would actually take my phone calls and answer technical questions. It is refreshing! I am grateful to Cummins, Inc. and their professional staff who are willing to talk to their customers about their products. I wonder if Navistar employees will take calls from Ford owners or if Isuzu takes calls from GM owners? Nahhh, I don't think so. Viva Cummins. Long live Cummins, Inc.
Another thread today got me thinking about the question again so I finally took the initiative to call Cummins, Inc. and ask. It took a while but I finally worked my way through the system and spoke with someone familiar with the ISB6. 7 who could provide good answers to my question.
Here's the answer from Cummins:
Hot shutdowns at egt up to 600* are acceptable and not likely to cause harm.
The turbocharger used on the ISB6. 7 has a higher heat tolerance than previous generation turbos because of the more restrictive emissions requirements on the 6. 7 and the need for regeneration of the emissions components.
Also, because the ISB6. 7 engine turbo is watercooled, it can tolerate hot shutdowns better. Our old TDR guidelines of allowing egt to decay to a maximum temp of 350* is no longer applicable.
The Cummins rep I spoke with today told me that a short cool down delay is desirable following full load, full power operation such as heavy towing at highway speeds but he said it is not harmful to shut down with egt as high as 600*. EGT can be this high if the engine was in the regen mode immediately before shifting to Park position.
I think Robert Patton wrote a similar opinion in a previous issue of TDR magazine where, IIRC, he stated that he routinely drives his Ram pickup w/ISB6. 7 engine like a gas engine. I think Robert said he uses no idle delay for cool down at all.
Cummins, Inc. is the only major American corporation I've ever tried to contact about their products and found that their employees would actually take my phone calls and answer technical questions. It is refreshing! I am grateful to Cummins, Inc. and their professional staff who are willing to talk to their customers about their products. I wonder if Navistar employees will take calls from Ford owners or if Isuzu takes calls from GM owners? Nahhh, I don't think so. Viva Cummins. Long live Cummins, Inc.
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