Do you let your Turbo spin down before switching off the Engine

MarkyX6 · Post by **MarkyX6** » Fri Oct 26, 2012 9:31 pm

I would be interested to know how may people do let the turbo spin down before they switch off the engine.

The salesman told me not to bother when I bought the car, but I have ignored that, and religiously let it run for at least 30 secs before I switch off.

Any views?

Mark

X5Sport · Post by **X5Sport** » Fri Oct 26, 2012 9:42 pm

No I can't say I do that myself. What I do do though is allow the engine to cool off a bit after a motorway run if stopping at the services. I'll start lifting off by the 1-mile marker so that the turbos aren't really being 'driven' as hard and the engine is doing little more than idling.

At home we have 20/30mph zones so the car gets a mile or so of 'cool down' coming off the dual-carriageway. I know with the X5 I could only hear its turbo when accelerating, but as soon as I lifted the throttle the turbo wound down again. I've never heard the X6 ones at all.

I believe the problem of 'cooked oil' in turbos really only becomes an issue if you have been driving 'enthusiastically' and then just pull up and switch off without a gentle bit of driving to allow things to cool first. That leaves a red hot turbo with no cooling oil flow.....nasty!

Richard

mogsyman · Post by **mogsyman** » Fri Oct 26, 2012 9:50 pm

I'm not sure these days you need to in 'normal' driving.

If you are giving it full chat and pull into your drive then I'm sure that's not good, but other than that drive and switch off.

Sent from my iPad using Tapatalk HD

535dboy · Post by **535dboy** » Sat Oct 27, 2012 10:42 am

[quote="mogsyman"]
I'm not sure these days you need to in 'normal' driving.

If you are giving it full chat and pull into your drive then I'm sure that's not good, but other than that drive and switch off.

Sent from my iPad using Tapatalk HD
[/quote]

+1

Gaff · Post by **Gaff** » Sat Oct 27, 2012 1:36 pm

Guys,
DO let your turbo cool down before switching off. I owned a Toyota Previa 2.0 D4D before my X. Used to run that bus hard, and WOULD let it cool down, but apparently not enough. The Turbo cracked cracked under the heat and sudden cool I was told. Cost me about £1200 to fix! I have been looking into TurboTimers. They would, once set, allow the to engine run for 1-5 minutes after you lock and leave the car with the key. This would allow the engine ample time to cool the turbo down. Any thoughts?

X5Sport · Post by **X5Sport** » Sat Oct 27, 2012 2:26 pm

Thoughts? Yes, goodnight DPF and they're a waste of fuel!

Turbo technology is rather more advanced than that in a Previa (Toyota withdrew them from the UK after 2006). Bearings are better, oil recipes specifically for the modern turbocharged engines developed, turbos are also more advanced and use new machining techniques.

jaynana · Post by **jaynana** » Sat Oct 27, 2012 6:20 pm

i allow a bit of of idle time before switching off the engine if i'm stopping at a service, after motorway driving. this is because there's often not enough cool-off time at slower speeds after easing off from like 90 to a total stop within a couple of miles.

other than that i don't bother, because even if its after motorway driving, the slow driving to the port of call would be usually enough to cool down.

this was actually recommended procedure in the 90s model land cruiser i had..

of course technology is much more advanced now but i still feel its good practice.

MJim · Post by **MJim** » Sat Oct 27, 2012 7:40 pm

I would have thought these engines are so torquey that barring hard acceleration, cruising down the motorway at 90 wouldn't be asking much of the turbo(s)?

IanP · Post by **IanP** » Sat Oct 27, 2012 8:30 pm

Never bother on the 4.6. No, wait, it hasnt got a dump truck engine in it

:pokey:

Turks · Post by **Turks** » Sun Oct 28, 2012 3:44 am

The amount of airflow through your intercooler on a motorway run would mean that there is no need to let your engine idle to cool down the turbo when stopping at a services. Additionally, the turbo is hardly working on the motorway at say 80 or 90mph unless you are in the wrong gear...

Remember that Turbo RPM is related to engine RPM and not the MPH you are travelling at. It will be generating the most heat when it has spooled up to full boost in 1st, 2nd, 3rd gear... unless you are driving like a nutter on a track or on the country roads, there would be no need to let you turbo cool down...

Turks.

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