Last time I was on the motorway, having cruised for 200 miles or so on the M6 and the M74, I pulled into a service area and parked up. The auto stop immediately stopped the engine. How does this fit in with the received wisdom of letting the turbo cool down before shutting off?

Not too worried if it is designed to be like that.

I've never worried about this, because I'll be off throttle at or before the slip road starts, and then I have to get into the car park, find a space and park before I switch off. That usually takes long enough to cool the turbo down.

It is absolutely fine. The oil pump continues pumping/circulating oil after the engine has stopped so there is no heat buildup within the hottest areas. Stop/starting is actually beneficial as it will lower the oil temperature throughout the engine and turbo during rest moments.

 

edit: The oil pump also runs for several minutes after turning the ignition off, so there is absolutely no need for a cool-down period after a hot-lap. It is very hard to cook a modern turbo.

Edited 15 March, 20179 yr by Orville

& if the Radiator needs the fans on for the coolant to cool the oil then on they come, and even if not the coolant is being pumped around the system when you stop.

They think of everything these days, and for a few years back.

@gregoir - similarly thought this as this is the first 'boosted' car I've owned, and had researched around the potential carbon build-up; but have peace of mind from the consistency of the Briskodian answers above. 

 

ALL - I'm assuming the oil pump / additional elements add to the slight whine(s) you can hear from electrical components after engine shut-off when outside of the car (i.e. not the Infotainment system whine)?

Edited 15 March, 20179 yr by Ads230

9 minutes ago, Ads230 said:

ALL - I'm assuming the oil pump / additional elements add to the slight whine(s) you can hear from electrical components after engine shut-off when outside of the car (i.e. not the Infotainment system whine)?

That's correct. The whine tends to be the oil pump circulating. The fan is much noisier, but on my car (VRS) it tends to shut off immediately when ignition is turned off.

Edited 15 March, 20179 yr by Orville

Was this every actually a real problem on Turbo engines except the Subaru or just an urban myth ?

Yes there was once a real issue that meant you were recommended to let the turbo cool down.

Nothing to do with any vehicles from when Stop / Start became manufacturers way of making emissions and fuel figures look like they were building environmentally kind engines.

It is the coolantpump you can hear after engine is shut down. Not the oilpump. 

Thanks guys. My car remains silent after the engine stops even at motorway speeds. Are you really saying that there is an electrically driven oil or water pump - does yours make a noticeable noise? I always thought they were normally mechanically driven.

Saying there is a coolant pump operating if needs must, i take it you are at about 70 mph on a motorway and you have not yet been doing that in the summer or hotter weather so when you are using the car harder and the indicated oil temp is high have a listen after you stop.

Thanks again. But is there just one, electrically driven, water pump?  From the description of the TSI engine I know that there is a fairly complex cooling system with several circuits to achieve a faster warm up.

4 hours ago, KjetilRos said:

It is the coolant pump you can hear after engine is shut down. Not the oil pump. 

 

 

This is what I always thought too.... It would make sense if both operated.

 

Are the turbos on these engines water-cooled as well?  Would make sense if that coolant-pump is circulating coolant to the turbo, moreso than the engine..... and I've been concerned about the immediate switch-off after a hot run as well.

But I figure the car is under warranty, and it would not have been engineered in a manner to cause damage..... but I just can't bring myself to let the stop/start do it's thing after giving it a thrashing or a long motorway drive.

I always switch the stop/start off so that the coolant can still circulate for a few minutes.

14 hours ago, Orville said:

It is absolutely fine. The oil pump continues pumping/circulating oil after the engine has stopped so there is no heat buildup within the hottest areas. Stop/starting is actually beneficial as it will lower the oil temperature throughout the engine and turbo during rest moments.

 

edit: The oil pump also runs for several minutes after turning the ignition off, so there is absolutely no need for a cool-down period after a hot-lap. It is very hard to cook a modern turbo.

 

There is no electrical oil pump on the engine, only mechanical one and it stops if the engine stops. Circled on the picture.

Water pumps however are electrical and continue to work even if engine stops if needed.

 

The risk of damaging turbo during start-stop is very small with normal highway speeds but after some brisk driving it is advisable to cool down the engine for a minute or two before shutting it down.

Edited 16 March, 20179 yr by Petunet
Pic

Can you point out please where the Biggest Car Manufacturer in the world ensured that Skoda, VW, Audi or SEAT have put the recommendation in the Owners manuals for the TSI engines that you let the engine run on for a few minutes after you stop or that you should switch off the Start / Stop if you are driving at around half the vehicles max speed?

(or even at autobahn type speeds!)

Edited 16 March, 20179 yr by Awayoffski

2 hours ago, Petunet said:

 

There is no electrical oil pump on the engine, only mechanical one and it stops if the engine stops. Circled on the picture.

Water pumps however are electrical and continue to work even if engine stops if needed.

 

The risk of damaging turbo during start-stop is very small with normal highway speeds but after some brisk driving it is advisable to cool down the engine for a minute or two before shutting it down.

You appear correct. I had assumed the oil-pump was electrical, but it seems I was wrong. My understanding is that the turbo has both water and oil inlets, so as long as one is pumping then cooling can continue after the engine has stopped.

Just relax! The engineers at VW/Skoda aint stupid

The turbocharger is watercooled, and there are an build in turbo timer that let the electric waterpump keep on running several minutes after the engine has stopped.

 

More generally, a mate of mine once had a SAAB 99 Turbo, which unexpectedly cut out after a period of, ah, spirited driving on a dark road. We were out to investigate PDQ, and as we opened the bonnet, we saw the turbo still glowing red, but that was a petrol engine, and maybe 10s after the engine stopped at ~4_500 rpm/

in a car that was designed 30 years ago....

Great cars though.

When my mate put his into the ditch showing me just how quick they were and his Scandinavian flick technik we were at least able to warm yourselves until a farmer arrived with a chain.

5 hours ago, Petunet said:

 

There is no electrical oil pump on the engine, only mechanical one and it stops if the engine stops. Circled on the picture.

Water pumps however are electrical and continue to work even if engine stops if needed.

 

The risk of damaging turbo during start-stop is very small with normal highway speeds but after some brisk driving it is advisable to cool down the engine for a minute or two before shutting it down.

 

Thanks for the information about the oil pump.

Have you got a similar diagram showing where the electrical water pumps are? Just out of interest, as my knowledge of electrical pumps is zilch.

42 minutes ago, gregoir said:

Thanks for the information about the oil pump.

Have you got a similar diagram showing where the electrical water pumps are? Just out of interest, as my knowledge of electrical pumps is zilch.

Not much to know, an impellor driven by an electric motor

10 hours ago, Awayoffski said:

Can you point out please where the Biggest Car Manufacturer in the world ensured that Skoda, VW, Audi or SEAT have put the recommendation in the Owners manuals for the TSI engines that you let the engine run on for a few minutes after you stop or that you should switch off the Start / Stop if you are driving at around half the vehicles max speed?

(or even at autobahn type speeds!)

 

Here you go

 

Edited 16 March, 20179 yr by PekoSI

5 hours ago, gregoir said:

Thanks for the information about the oil pump.

Have you got a similar diagram showing where the electrical water pumps are? Just out of interest, as my knowledge of electrical pumps is zilch.

 

I have 2.0 TDI diagrams but you might be interested 1.4 TSI related info.