Idle before shut down on turbo Z4

A

abientostyle

Member
Apologies if this has already been answered. Done search but nothing came up.
Every turbo car I have driven I have allowed it to idle for a bit before shutting down especially after a long hard drive so the turbo doesn't suddenly stop getting oil and coolant and cook.
The BMW guy said that this isn`t needed on the latest 2.0 turbo. I`m not sure especially with the stop start function where you could have the turbo spinning then suddenly come to a stop and the engine temporarily shuts down . I disable this SSF and idle for approx 30 seconds before shutting down. Anyone got any advice/comments on best practice?
Thks.
 
Ive windered this also, although with my diesel 1 series with SS.

As you say they must have found a solution, as its possible like i did to drive 100 miles up yhe M1 then pull off the slip road and get stopped at traffic lights only for the engne to cut out.

As mine is a company car i am not so worried, but for peace of mind it isnt going to harm if you idle for a while before switchng off.
 
Me too

But on my focus, if you open the bonnet once it has had a thrash the turbo is glowing comeing to a stop and the engine stops cant do it any good

But im not really fussed like srhutch its a company car

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I'm on my second turbo deisel co car and I've never bothered letting the turbo slow. Hasn't done either car any harm whatsover. Can also say all my colleagues do the same thing and again no problems. Cars include Audi, VW, Ford, Honda, Citroen and Vauxhall so a goodly spread!
 
BRC said:
I'm on my second turbo deisel co car and I've never bothered letting the turbo slow. Hasn't done either car any harm whatsover. Can also say all my colleagues do the same thing and again no problems. Cars include Audi, VW, Ford, Honda, Citroen and Vauxhall so a goodly spread!
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It's always been good practice to do so though. I remember when I bout my first BMW diesel 11 years ago and the dealer advised to do so back then. A habit I was already used to have previously owning diesels.
 
never done it.

dont particularly care as it is under warranty and by the time it expires, the car will be returned to the dealer
 
The stop start is a bit different to just turning the engine off, AFAIK the cooling system still operates during the 'stop' period.

On any turbo cars I've had previously I did the same as you, and also took it slowly for the last mile or so, keeping the revs low. Can't do any harm, even if it may not now be 100% necessary.
 
Problem as I understand was the oil stopped pumping around the turbo so cooked it. Perhaps as you say the have integrated the flow of the collant through the turbo to do this.
 
Probably one of those things we should do but the overall gain might be marginal and less so as turbo's continue their evolution. I'll be getting my third in 4 months and this might be a car I'll keep/pass on, so I may well think twice before I switch off. Have to say if this is the case then normally aspirated has more merit than I first thought. :D
 
If its anything like the JCW mini we had.The coolant is circulated after the car is turned off for a while to cool the turbo down if it is very hot.

Can you hear a pump sound after you park up ?
 
Tubos use the very hot exhaust gasses to operate and spin at very, very high speed thereby putting an enormous strain on the bearings and their lubrication. If the turbo is not allowed to cool then, in days of old, the mineral based oils used to get cooked around the bearings and, eventually, the turbo would fail. Modern fully synthetic oil has significantly reduced this risk as they are a dose more 'robust' than mineral based oils. Having said that, it is still good practice to let the turbo 'spool down' before switching off.
 
Slightly off topic but --- Its also not a good idea to set the handbrake after heavy brake usage. Let them cool first.
 
As mentioned above if on stop start the oil pump runs, I would expect bmw to have covered this and it will run on power off, like the rad fan. Unless you are on a race track I would doubt even having fun down our country roads then a mile at 30mph would cause any damage compared to unrestricted German roads.

Do what you think, its not detailed in the manual. Only time my engine is ticking over on my drive is to raise the roof.

I also do not rev the engine when I switch off

When I start Im off, unless Im defrosting it. I do a mile at 30mph then hit country roads so drop into 3rd and up to 60 but I dont red line it when cold. I tend to be up at the highest gear I can.
 
jaz4 said:
As mentioned above if on stop start the oil pump runs, I would expect bmw to have covered this and it will run on power off, like the rad fan.---------
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You're not suggesting that the oil pump runs with the engine off are you????
 
Not suggesting anything or surprised if it did or something else happens but BMW and technology now would not allow the engine to be in any harm by simply turning off the engine after a bit of spirited running. Stop start can be inhibited at certain times, mine works like clockwork.

If we are track racing then consideration must be applied, or stage 2 and 3 mods but for normal use nahh. Reverse in the drive and switch off.
 
I have run a turbo Z4 (3.5i) for a year now and always switch it off immediately I pull up on the drive. I don't believe BMW say anything about leaving it to idle in the handbook. My car is in any case covered by a BMW Used Car Warranty, so if the turbo did go wrong I guess it's not my problem. The car has a double clutch transmission so has no Stop Start Function (thankfully!).
 
I always do a cool down lap and them let it idle for a couple of minutes when I'm on the track but day to day use I don't bother as it doesn't get as hot. I also just put it in park and don't use the handbrake.
 
So according to the N20 pdf the cooling pump runs independently and runs to cool the turbo down. As I would expect.
 
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