What are your thoughts on Turbo cool down, how long do you let it cool before shut down, or do you say screw it and leave it?
I don't usually let it sit for long when I come home. I figure since my engine is stock the egt's probably stay in a safe, constant range. I do however let it cool down if I was pushing it a little hard, and at lower RPM's, right before getting home. I always let the tractors and other diesel powered farm equipment around the ranch cool down first because they run at full power and load 95% of the time.
GM says there is no need to cool down the DMax turbo. And I usually don't since it generally has time to idle a while when I pull of the interstate or places that it would be getting high EGTs. However, if for some reason I go directly off load/boost to a stop (like to deal with a blown tire or something), then I let it idle for a couple of minutes just for my own piece of mind.
With my pyro located post turbo I make sure my EGTs are below 300* F. before shutting down the engine.
I usually let it cool down only after hard uphill pulls, then I let the EGT's settle down to 300. It's hard to get the EGT's up there when pulling on the flats. It usually takes about 2 minutes max to cooldown the turbo. Other than the hills I never worry about it. Rob
I have no way to tell if I 'need' to let it cool down. I did read about it though. So after my commute I kinda sit there int he drivway and let it idel fer a bit then shut it down. This rig I have is great for keeping a nice calm pace in my day to day driving. I find myself just taking my time and it's great. I wait to start it, I let it warm up, I drive it, I wait to shut it down, I drink a beer and the day is wonderfulwaytogo I already have 9K on itimp: I don't care what anyone says I Love My Dmax/Alli,CC,LBed AWSOME!!
You could steal a product from the ricers. Not sure if they market them for pickups but the turbo equipped ricers can install turbo timers... If you haven't heard of them, they are a small box that hooks into your wiring and let the engine idle for a preset time after you turn the key off. They have a safety feature that is hooked into the e-brake so if someone breaks inot the truck while it is idling and releases the e-brake, the truck will shut off. They are pretty cheap at around $100ea. and they dont look to be too hard to wire in...
The reason to cool down your turbo is so the oil doesn't cook in the bearings. If I've been pulling hard I'll let it cool off. By the time I've run in easy to the yard and parked the truck and trailer my temps are down. If I pull over someplace and am leaving in 5-6 minutes I lock the doors with my spare key and let her run.
On the electronic motors in Class 8 trucks they have a shutdown timer built into the ECM. Most company's have them set for 20 minutes with no input such as blipping the throtle. For them its a fuel savings measure.
Yeah, I know why it's done and it makes sense on the big boys. But on the little trucks, even the manufacturer with warranty and bad-press issues to worry about, they say not to worry about it. All that said, I do wait for mine to cool down if I stop right off a hard pull. Usually watch the EGTs at least till they stabilize in the 3-400 range for a little while, no more than about 2 minutes total generally. But like you, I usually wind up with more than enough cool down time by the time I idle around the gas pumps (where I leave it running while filling anyway), or to the back 40 for trailer parking, or getting everyone organized at the trail head, or whatever... Edit: Oh, and that is 3-400 pre-turbo, and that's why I wait a bit after it drops to that point so the casting can have time to cool too. Pre-turbo it will hit those numbers within a minute or less (never timed), so I give the casting another minute. But like I said, only if it does not get the time otherwise by idling around.
