Morning engine warmup??

[Rawze]

A long time ago, several years in fact, I spoke with a technical representative from Holset. This is what I learned about turbochargers in general ...

The guy said that the number one cause of failures back then was carbonized bearings in the turbo. Of course, the VGT's were relatively new then, but it is still important information ...

As far as shutdown goes,.. a pyro on the exhaust manifold to measure the manifold and turbo temps is best. Anything below 400 degrees on the manifold temp is safe to shut down the engine. Otherwise, you will cook the oil in the turbocharger once the oil and coolant stop flowing. This is called "carbonizing the turbo bearing" and is not a good thing.

Now just think about that guy who climbs that hill at full engine load then gets to the top only to shut off his truck at the truck stop. -- What a shame.

I also found out that the VGT's (and non-VG's I think) can withstand 1360 degrees for 3 minute periods without worrying about heat xfer into the face and mechanisms at lower flow rates. At higher flow rates, it can withstand it for longer periods. It comes down to the amount of absorbed heat overall and equated to roughly about 900 - 950 degrees on the outer casing before having to worry about turbocharger temperatures. Small turbo with lots of restriction = more absorbed heat. Bigger turbo with better flow where the heat can move past it more easily = less absorbed heat. Also, exterior cooling helps too, like forced air from an engine fan.


Some call me a crack-pot, but it was the very next week, I installed a pyro gauge and placed the probe onto the outside of the manifold instead of putting it inside it. I have lived by the rule of shutting off the truck when the turbo is below 400 degrees F. and not letting it get above 950. -- First turbo lasted 580k miles and dies because of stupidity on my part. I shut truck off when turbo was at 900+ degrees (280k miles on the turbo), not thinking, and it started acting up after that. It was never the same after i did that to it and it slowly got worse. It lived all the way to 580k and got real bad, so I replaced it.

Second turbo is still on the truck and has now 610k miles and still going strong. -- Just to add to this,.. the circuit board that sits a top of the thing inside the turbo actuator is electronic. Solder holding the components to the board melts sometimes at as low a temp as 450 degrees, and certainly at 500+ degrees. Coolant flow and outside airflow is the only thing keeping it from getting too hot -- Just an observation.