Is it necessary to allow the turbo to cool down if you are: 1. Not towing, 2. Not hauling butt down the interstate 3. Not climbing Mt. Everest, but are just driving around town? The engine and tranny are up to temp, and I'm not going over 40. When I get home I let her run for 5 or so and then shut her down. Do I need to do that?

"03" F350 Lariat SD Dually

 

Do you have gauges? Most importantly the Pyrometer? If you do the 300 degree mark is where you can safely shut it off. If you do not have gauges then the way you are describing how you drive usually, I pull in the drive way undo my seat belt put the sun shade up and it is cool enough. So 5 min is way overboard on empty normal driving in order to cool it down. Towing is whole different story. If You are towing you better get some gauges anyway.

 

If you had a pyrometer, what temperature would you be interested in?

One thought is that the output temperature (post turbo) would be a better indication of the turbo shaft & impeller temperature. A pre-turbo sensor would only tell you how much heat remains in the manifold. The issue for turbo seems primarily cooking the oil after the oil flow ceases (engine shutdown).

As some of us face deciding where to mount our pyrometer sensor, the cool down temperature may offer a bias to post-turbo sensing.

Pre-turbo Mounting:
+ Better indication of gas temperature for impeller when operating
- Installation pre-turbo may subject bearings to metal shavings from installation.
- If pyrometer fails, damage to turbo is likely
- More likely Ford warranty issues if turbo fails (from un-related issues)

Post-turbo Mounting:
+ Lower to non-existant concern of installation damage from metal shavings
- Turbo input gas temperature must be estimated (e.g. 300-400 deg F higher)
+ Possible better indication of when turbine is in a cool state for shutdown
+ Access to installation better (assuming bung is welded in down pipe during aftermarket exhaust installation)


Any thoughts?

 

300 degrees in pre turbo mount. The post turbo mount is basically worthless, as it does not tell real time temps and lags therefore under heavy load or acceleration by the time you estimate the temps it is too late and the damage to the cylinders and heads is done. How ever his question was related to time to cool down not placement of the probe.

 

Rooster,

Thanks for the feedback that the pre-turbo mount is correct and 300 deg F is your shut down point. As I don't yet have the BD X-monitor or CES installed, I can't comment on time, so didn't. I am leaning strongly to pre-mount for the pyrometer.

In absense of guages, I have been waiting about 20-30 seconds in a non-tow scenario. Have not towed yet with new truck.

Thanks,
Pete

 

With my pre-turbo Pyrometer, I sometimes see temperatures above 300 just idling in the summer, mostly with the A/C turned on. I wonder if my gauge is reading a little high? If so, I suppose that's better than reading low!
My theory is that there is as much or more thermal mass in the exhaust manifolds as there is in the turbo and pedestal etc., and that the turbo would be cool enough if the pre-turbo reading is below 400.

The turbo minders I am aware of use 300 degrees (post-turbo) as the shut off point and in my mind anything under 400 degrees pre-turbo should be good.

OK now you guys can help me figure out where I am thinking incorrectly...

 

You should be fine anything less then 400. You want to see 300 but the biggy is really just not running it hot and then shutting it off blah blah. Yes the A/C does cause the EGT's to be up a little as as the tranny being in gear. So once you put the truck in neutral and shut off the air you will see temps down closer to 300. Also a larger intake and exhaust help tremendously.

 

F350 Dually, for what you are doing you do not need to let it cool down. even if you are running along the freeway not towing it cools down faster than most people think.

 

When we went to turbos on our fire trucks the factory rep(cat) told us to let it idle for 30 seconds. If it had ben run hard 60 seconds. Not as good as a gauge but it is a good guide line.

 

I agree. I have been driving turbos for 20 years like that and I have never lost a turbo yet.

Dean