6.7L Cummins Forum - View Single Post

Garlic · #5 (**permalink**) 01-29-2010, 08:31 AM

I believe cool down is still one of those 'old' school or habits that people get used to. I am not advocating that letting it rest (cool down, stabilize) for a period of time is bad, I think they should. I have replaced very few turbos suspected of failing because of not letting them cool down before shutting the engine down, I figure probably 1 in 100 may have been caused hot a hot shut down, but not likely, mechanical problems have killed more (over speeding, oil quality, poor air filters). I however do watch mine closely and attempt not to shut the engine down when the temps are over 800*. The wife however really does not care much, drive it, park it, kill it (just like the family sedan). For instance say you are toting the barge, EGT temps are over 1200* and you coast off the freeway, come to a stop sign, wait for traffic to clear, proceed to cross the road and about 3 or 4 blocks later you find the McD's and pull in. Slowly you come around the corner and find a place to put the rig, gather your thoughts and what-nots (some have more of these than others) then you shut the engine off. This all transpires to cool down, I have noticed that the EGT's are about as low as they are going to get with out making your bladder burst. 6.7l's have an advantage though, a water cooled turbo, they will remove a bunch of heat evenly from the unit real fast. If I do not have to bail fast, I will allow things to stabilize more, Esp the coolant temps. I have seen 225*+ and 600* EGT at shut down, restart the engine after a hot soak like this the rpm will rise to a high idle and the fan comes on. I feel uneasy about allowing the truck to run (even with the doors locked) unattended for any period of time. Bottom line (IMHO) Hot shut downs are not good for any engine component (Even Gassers should stabilize first), allow the system to come to the average operating temp then shut it down. Restart should be treated the same way, start, stabilize and go easy until the temp (coolant) starts to rise. Sorry for the rambling, just my $0.02 worth. A timer is a good "set it and forget it" feature, if you have that function, use it, my target would be 450* to 500* (pre-turbo). I have a hard pull I will make this weekend and will watch the temps to see exactly where they go, esp for getting off the freeway and going into a rest stop.