[Grumbleweed]

Just wondered if anyone has technical knowledge concerning the Turbo in the Q3's.I have had several diesel cars in the past and the advice has always been to allow the engine to idle for up to two minutes depending on how fast you've drivenafter a long trip which lets the oilcirculate into the turbo preventing dryness.Like the rest of us my Q3 has start stop technology. Are Audi just going along with "the green party"and hoping the turbo will stand up to this treatmentor has it been designed to withstand such use?By the way I have had it now for just seven days and love it.

 

[rontheman]

The requirement for a 2 minute cool down is a valid one, but is really only relevant after a high performance run, ie a motorway trip at high speed. Usually, there will already have been a 30-60 second "cool down" if, for example, you turn into a service area.However, one should allow the turbocharger to cool down for 2 minutes after use, but in reality, I don't believe anyone does.

 

[Grumbleweed]

Many thanks rontheman. I will switch the start/stop off during motorway trips. Just to be on the safe side.(often it is necessary to stop for traffic congestion)

 

[Daddy k]

Mines not arrived yet so I cannot check. However on the 225bhp mk1 TT, there's a water pump that continues to flow water around various engine parts to aid cooling after turning the engine off.
You can hear the pump running.

 

[Phill-uk]

It's a modern car, it does everything automatically for you. Just drive and enjoy.

 

[Jules]

Why do people worry so much about turning off the stop/start? My biggest problem with it, is making it work - lol there are so many reasons why it doesn't cut in (air temp, engine temp, battery load, air con etc etc etc), it's almost a pleasant surprise when it does!
I do remember talk of letting Turbo's cool for a bit after a long run - but I agree with Rontheman - it's a rare journey that goes from 70mph to dead stop - even with my driving

 

[SeaBox]

The idea behind allowing a any turbo charged engine to idle for a minute or two after a high load is to allow the engine oil to continue to be pumped onto the turbo charger bearings while it is still spinning at high speed. Turbo chargers can spin at over 100,000 rpm so if you have been on a high load and then immediately switch the engine off the oil pump in the engine will stop circulating oil whilst the turbo is still spinning. This can cause the remaining oil on the bearings to overheat and carbonise. The carbonised oil then goes solid and lumpy and restricts oil flow to the turbo next time you start the engine, this is the beginning of the end of your turbo bearings!
It might not say it in most handbooks these days but it is good practice to allow the engine to run for a minute after high load, it is mechanical sympathy much like not thrashing a cold engine.
Audi like all other manufacturers have to fit start stop to meet emissions regulations and to keep with environmental 'fashion' however start stop is potentially not good for your turbo for the reasons given above.

 

[rontheman]

An additional reason for allowing a turbo to idle for a short while is to reduce the temperature shock loading, ie to avoid shock cooling by going from high temperature to off suddenly. The same principle is applied with a turbocharged aircraft engine after landing, ie let it idle so as to minimise heat shock

 

[Grumbleweed]

Thanks to you all for your help in this matter.