H

I have a 2.7T (nicest car I've ever owned BTW). I've seen several posts saying that one key to turbo longevity is driving slowly or idling for 30 sec or so before shutting the engine off in order to allow the turbos to spin down while coolant is still flowing.

I can almost always hear a whirring for several seconds after I shut off the engine. I believe is the turbos spinning down. This happens even when I idle the engine before turning it off. Any comments? Should I be concerned?

ErikR

The turbos are quite difficult to make out, and I certainly doubt you can hear them spin down. Just do as Audi advises, let it sit for a 30-60 seconds after a hard run, or not at all if you are just loafing around.

Wavshrdr

It is a good idea though to let it idle for a minute or so if you are running it hard. Turbos can actually get hotter after you shut the car off. A few minutes of idling can GREATLY extend the life of those precious little power boosters.

Jack Orr

Goodness, guys-this has all been posted before- and should be common knowledge. Anyhow, there is a little pump that circulates coolant to the turbo bearings. After shutdown. SOP. I'm not sure, but Audi may circulate a little oil too, but I don't thinks so. Therefore, idle down is not quite so important as it used to be, but I'de do whatever the manual calls for. THEN, at 5000 miles or so, go to Mobil 1. Realize that all the heat a turbo generates is because it revolves at many thousands of RPM- some go as high as 30,000.

JP4

Driving slowly or idling for 30 sec or so before shut down IS important to increase longevity and efficiency of the hot side of the turbine. The "cool down" period before shut down allows temps to stabilize so the temp change is not so abrupt and dramatic. Abrupt and dramatic temp change is what shortens the life span and efficiency of turbines prematurely. The turbine blades are constantly expanding and contracting with rises and drops in temps. This is normal. Over time the turbine begins to loose efficiency because the outer edge of the blades are not as close to the sides of the case as when new and gas that could be used to spin the impeller is bypassing the process. Gradual cool downs tend to minimize this effect. But keep in mind that it can not be eliminated. This is just the nature of the beast.

Hope this helps.

April

Actually, there is a pump that pushes coolant through the system after shut-down

April

Still cool down turbos by low demand driving for a minute or so

ErikR

I did some fact-finding and discovered that they did go ahead and put the afterun pump in. I would still not do a hot shutdown, even with synthetic, as the *bearing* is a hydrostatic one formed by the oil. (Considering how many people STILL don't use synthetic, I'm leery of a broad statement that can be misinterpreted.)

Bollinger

I thought that was the turbos also and was concerned. Next time I brought my car in to park it, I turned off the A/C 30 seconds before I stopped. All else was the same.

Result: no "spin down" sound after key off. The sound is just the A/C fans spinning down, not the turbos.

As ErikR said, the turbos are quieter than that anyway and a little more whiny.