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Is this really true?


GBMUD
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http://www.carkeys.co.uk/features/product/2006/12004.asp

The bit about having to allow the engine to idle for 30 seconds before you turn it off? I know one should allow a Tdi to cool down for a minute or so after leaving the motorway/sustained heavy use but this suggests the new TDV8 should be allowed to cool after a quick spin to the shops. And 120degree under bonnet temperatures? Surely people will burn themselves on the bonnet!? Still, that's progress. :)

Chris

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well ALL turbo charged engines (apart from those with pre and post lube kits) either need or benefit from idling for thirty seconds. The bearings a turbo can get incredigbly hot- if you come to a halt after a good run and then just stop the engine then the bearings are still in congtact with very hot oil whilst beiung extremely hot themselves. What happens is that the oil starts to burn, and the bearings have all sorts of increased wear problems. This is exacerbated by the uneven cooling thbat occurs from very high temperatures.

If you wait 30 seconds with the engine at idle then the engine pumps cooler oil around the turbo and cools the turbo slowly- you end up with much much longer life turbo. Obviously the more high performance the engine then the more boost and heat the turbo is handling which means the necessity for cooling increases- with a diesel and variable valve geometary i would guess that the fact that the turbo is on-boost almost all the time would mean that turbo cars is even more important. I'm quite surprised that they haven't put in a post pump that supplies oil to the turbo when the engine is switched off.

I had a nissan 300zx (a twin turbo V6) once which was a really nice car- until after a pretty intense run i stopped the car very suddenly and went into the pub. Only to rush out a minute later after lots of shouting to find smoke boiling out of the engine bay- the turbo had seized and started to set alight to the oilil!! i managed to get one of the turbos turning again by starting the car but one of them was ****ed- cost me an arm and a leg to repair!

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As they are obviously fully aware of the problem, it seems to me that a £50K+ car should come with an automatic turbo timer to avoid cooking the engine. I'm sure it'd take a bit of getting used to a 30sec over run when you switch off the engine, but rather that than destroying an engine through 'normal use'.

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i thought turbo timers were technically illegal as the ignition switch had to cut the engine off for safety in accidents. the other suggestion above of an electric oil pump that runs for a set time on switch off would solve it though.

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