Vino

I have a question I hope someone can answer.

Most Turbo owners I know say the key to keeping Turbo Charger longevity is to cool the turbo before shutting the the car/truck off after the car is warmend and driven on average use.

Question is, when we purchased our CT we were told there was no need to let the truck idle after longer trips to cool the turbos? Is this true or was I fed a line?

I have not heard of any turbo failures thus far and no talk about it.

Has turbo technology been improved?

Let me know what you guys have been doing as I know for a fact on older turbo cars, if they're not cooled for at least 1 min. then the turbo fails quicklier as the oil can cake on to the bearings.

Thanks!

mudman2

If you listen closely you may hear the coolant circulating after you turn the engine off by design. So the statement was not a line, you are not involved in the process of cooling the turbo's

Periokid

I agree with mudman and also the use of synthetic oil helps too (ie it does not coke up in the turbos when it sits).

Vino

You guys make owning these cars enjoyable and I appreciate the quick response.

It's nice to know we don't have to sit in the Garage for 1 minute after driving it from today on.

Just want to make sure as I couldn't find anything about it in the owners manual.

Thanks again!

Andre

Moogle

many people idle their turbocharged cars for a minute or two before shutting it off.

worth it for peace of mind, in my opinion

cobalt

What you are worring about is a problem associated with the older 911 turbos. When you shut the 911 engine down the oil dumps back into the dry sump tank with no circulation left to cool off the hot turbo. This would cause premature failure of the turbo. I agree with mudman and see no reason to be concerned.

docjackson1

this same discussion is going on now on the 996tt board. much the same answers. in your auto handbook, pcna says nothing about idling the car.

mudman2

its actually mentioned in the Cayenne Technical Information manual

docjackson1

what do they say mike?

mudman2

Just what I wrote before. After the engine is stopped the electric cooling pump continues to run to cool the blowers.

FSAEracer03

I personally take the owners manuals with a grain of salt. These are the same manuals that have perscribed oil changes with no filter replacement and 15k mile real oil changes! Call up Mobil and ask them if they did any studies to show this was ok... or what they recommend.

It was not only a problem with the 930s, because it's not just the lack of cooling fluid flowing through the turbo(s), its the fact that you get turbos red hot on spirited runs, and they need a little time to cool down. If you let it idle for a while, it gradually cools down safely. If you shut the engine off, the temperature drop is far too fast and the turbos will prematurely fail if you do this regularly. Heat doesn't cause warpage or parts to fail, heat exchange does. This is why the turbo timer was invented... so people could drive turbocharged cars "spiritedly" and leave their car, while a timer idled their car for X seconds, then automatically shut down.

If I get a little sparky on a run, and really wind up the engine, and work the turbo a good bit, I drive in low rpms home (or where ever I'm headed) and let her idle for a minute or two. Even after all of that the cooling fans and turbo cooler are still working after I shut down.

If you don't use the turbos much driving normally, don't bother with all of this. Just remember that when you do drive it hard, let it calm down before you shut down.

Brent 89-GT

What you were told is correct for some cars. Turbo technology cured the problem for the most part with the introduction of a water jacket around the turbo center bearing. This used to be an oil only enviroment, and that is the case with the air/oil cooled Porsches. Upon shutdown the flow of oil stops, in most cases the turbo is still spinning to some degree. That plus all the heat, remember they are exhaust driven, used to cuase the oil to "coke" in the bearing. The result was pretty much like adding sand to the mix and toasted turbo bearings quickly. Running the engine at idle was done to allow the turbo to cool, just as you were told. Porsche, starting in '86 with the 951 (not sure about 931's) used a water jacketed turbo bearing and aux circulation pump that ran after shutdown. These two changes allow the turbo to easily make 100k on those cars. The Cayenne TT uses a similar system and what it means to you is that, unless you have just come off of the racetrack, you need not worry. The 951 system was on a timer, I wonder of the 996TT and C TT are any more advanced? Does anyone know if they monitor temps to determine shutdown of the aux pumps?

There is the longwinded explaination

bancu

"The electric coolant circulation pump is switched on as needed in run-on operation together with the electric cooling fans by the DME control module."

Could be reading it wrong but it sounds like it is more than a timer.

Moogle

so whats the concensus? do the newer cars have some sort of device that automatically leaves circulates oil in the turbos even after you shut them off?

do the old ideas of cooling for a minute or two still apply? (shoulda made a poll ).

personally, no matter what is agreed here, ive heard enough from various sources to just let it idle a minute or two. i'm never in THAT much of a hurry.

bancu

It doesn't seem like there's any oil circulation on the Cayenne. Wouldn't just circulating the water be enough since the turbos are water cooled?