How long to idle in the cold?

[CJEliassen]

OPJohnny,



I think that the oil live leaving the turbo might be a good reading to have a turbo cool down device on. When it drops to a constant temperature, the engine shuts down.

 

[cojhl2]

Reason for cooldown idle

I always thought the reason for cooldown idle was to give the pistons a chance to normalize down to a reasonable temp before stopping them. Long before turbos were a standard item on class 8's we always idled for cooldown.

In my opinion,, turbos are just another item to watch,, not the only one. Also, I believe it takes much longer for the pistons to give up their hotspot than that of the turbo. (I go for long cooldown idle after hard pulls!)



Also Im pretty sure my Cat has post turbo temps as it usually runs about 300deg. I dont think they would have put a EGT in the wrong place would they?



((This has been an interesting and informative thread))

 

[opjohnny]

CJEliassen, thats what I was thinking, in the oil line return. Your blowing ~300deg F ex gas and pushing ~190deg oil past the bearing. We have a bunch of things going on. I would like to look at engineering drawing of the turbo. That is some temp gradient going across that turbo.

 

[rbattelle]

A good discussion

Now that was a good discussion between me and CJEliassen... it didn't get personal. Whether we disagree on some of the finer points is of no consequence, what matters is that anyone reading hopefully learned some piece of useful information and formed their own opinion.



I very much agree that a bearing temperature gauge would be an excellent investment in turbo life. One way would be to measure oil returning from the turbo (my opinion) or another way would be to mount a thermocouple on the outer case of the bearing (my opinion). Not sure which would yield "better" results.



Opjohnny, I'm pretty sure on Holset's site you can download a PDF manual for the turbo which includes some decent drawings.



-Ryan

 

[Kennywould]

I know one thing for sure, there is a lot of intelligent people here with varied opinions and knowledge. I for one have driven and operated all types of equipment with turbo diesel engines without pyro gauges and common sense is to idle down to cool down, whether its for seconds or minutes, it depends on how hard its been run. If you pull 10,000 up the road for a while you wouldn't shut it down in 15 seconds, same goes for running an empty truck, you don't need to idle it for 10 minutes. Same if your pullin with a 48re, you have to idle it in neutral for some time if you been pullin heavy, regardless of what the pyro says, you know that the oil has to pump thru the cooler to cool that transmission. You can't rely on one gauge to make your decision to shut down! Your brain is the most important gauge, it and common sense should keep you out of trouble, IMHO