After a few years of running a trouble free petrol RR I’ve taken the plunge and bought an L405 but it’s a diesel. I’m sure i’ve read somewhere that you need to allow the turbos to “cool down” before switching off after a journey (it might not be cooling down but you get the picture). On my arrival home I drive though our estate for about half a mile at 20mph - would this do it or do I really have to sit on my drive with the engine running for 5 minutes with the dog try to jump through the window .? Geoff

Turbos need to cool after they have been worked hard and you need to ensure there is plenty of oil through the spindle bearing before shutting down whilst cooling. The typical example would be coming off motorway in to services and turning engine off straight away. If car was being driven hard turbos are hot, oil evapourates in bearing once flow stops on shutdown. So let it idle for a while after parking.

Same after working car hard on main road and then pulling In to a layby and stopping engine straight away.

Reality is at normal road speeds on a big diesel , esp rr 4.4 where revs are low turbos are seldom worked that hard with normal driving.

Any slow speed driving, such as you suggest would help turbos cool and reduce need for an idle period.

As a rule I turn mine off after taking off seat belt so it idles 20~30s after 2mins or so of 10mph driving. Cheers

James

I honestly think you would struggle to work the Range Rover turbos hard under normal road conditions so I wouldnt worry too much about the cool down. Diesels run cooler than petrol turbo's anyway. My regime if for example Im towing my caravan and intend calling at a motorway service area I slow down to 50 mph a mile before the services, then the drive to the parking space will allow enough time for any cooling needed.

Dont worry about it you will be fine. BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

Equally as important is to ignore the stupid modern fashion for extended service intervals for oil/filter changes and do it every 10,000 miles with good quality oil of the correct spec. Drives:
2010 FFRR TdV8 Vogue - Stornoway Grey
2010 FFRR TdV8 Vogue SE - Zermatt Silver
1998 BMW E36 M3 GTII

Unless the turbo has just been worked hard, I just take the time to close the windows and sunroof, turn off the radio, grab my phone and then turn the engine off. The 20 seconds or so that lot takes should be enough to dissipate any residual heat in the turbocharger bearings

I suspect most users wouldn’t bother, but a bit of mechanical simpathy never did any harm

Motorway petrol stations are the only time I leave mine running.

Other than that, I’ve done enough at slow speed not to worry about it.

My understanding is that the turbo keeps spinning once you’re off the throttle - if you immediately kill the engine, then it’s spinning with no oil being pumped. So you leave the engine running long enough for the turbo to come to rest whilst still being bathed in oil.

I’ve no idea how long that takes in. FFRR, but a few slow minutes seem enough to me.....

I went googling and found this:

https://www.team-bhp.com/tech-stuff/idling...arged-cars

The real problems are highly stressed petrol eg Cosworth Sierra this was a favourite. Give it some wellie and the turbo would glow bright red, switch off the ignition the residual oil is burned, the turbo still spinning and the oild fried rendering a mess of carbon. The inner parts of the turbo near white hot.

Have a look at this AMG Merc:

https://www.youtube.com/watch?v=0gLBC_tgwFw



[/url] BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

Interesting

Imagine the fun LR must have had developing their first turbocharged engines, knowing that the red hot turbo might get immersed in water at any point

Imagine also, how long that turbo is going to take to cool after a sound thrashing like this! Two or three minutes of idling will make little difference.

The difference here is a) were diesel and b) were not to work it that hard so nothing to worry about. I helped my son develop his 1300cc Toyota engine, now produces over 400 bhp, the turbo on that was a nightmare. It now has a turbo timer, you switch off the ignition and can lock the car and walk away, the engine idles for 3 minutes. During this time it can only idle opening the throttle etc does nothing.



Its even been know to catch the odd Ferrari out hehe



AJG BMW i3 Electric Car
2012 Full Fat RR 4.4 TDV8 (now gone)
2006 VW Touareg 3.0 TDi V6

takes me back a few years - I had a Subaru Impreza with one or two modifications - that’s where I learnt to respect a turbo after a good thrashing.

As you correctly point out, the diesel turbos run much cooler and slower than the petrol ones, but the theory is still the same.

I often wonder whether cooling off time was part of the 3.6 tdv8 unexplained turbo failure story.....

Normal driving is fine - it’s when you have been driving with your balls hanging out or towing a massive load when the engine and oil is really hot that it needs to cool down before shutdown - if you don’t in these circumstances the oil cooks on the turbo bearings and it’s curtains in a very short space of time. RR are usually fine - it’s high output diesels in Trucks and Tractors that must be idled after hard work.

These days due to manufacturing tolerances a Turbo will outlive the engine - it’s more common for an engine to fail due to a knackered water pump and overheating before a Turbo fails. Honestly Turbo failure these days is the least of anyone’s issues and I am speaking from experience with a fairly large fleet of various diesel vehicles and plant in all shapes and sizes 2021 L405 Vogue SE 4.4 V8 DIESEL ~ #17

supershuttle wrote:

After a few years of running a trouble free petrol RR I’ve taken the plunge and bought an L405 but it’s a diesel. I’m sure i’ve read somewhere that you need to allow the turbos to “cool down” before switching off after a journey (it might not be cooling down but you get the picture). On my arrival home I drive though our estate for about half a mile at 20mph - would this do it or do I really have to sit on my drive with the engine running for 5 minutes with the dog try to jump through the window .?

Geoff, if you feel the urge to take your new car on a track day then YES, you need to allow the turbo's to cool before shutting her off...If you drive her like any half decent citizen then don't worry about the turbo's cooling! At anything under half throttle and 50mph your turbo's are only just ticking over sir...