FAQ: Turbo cooling period before shutdown....

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Deleted User 759

Post by Deleted User 759 »

A number of members have commented that dealers have advised them to leave their engine running for up to a minute before shutting it down. The idea behind this is to allow the turbo core to cool sufficiently to avoid oil in the bearings from boiling and coking up. This could lead to premature failure of the turbo which is often an expensive repair. Modern turbo's have water cooled cores, this keeps the turbo's core temperature under control during operation as well as in shutdown. Even with the engine switched off, water will still circulate around the engine which will remove excess heat build from the core up through heat soak from the engine head, exhaust manifold and turbine housing. Having water cooled cores should mean that there is less need for a shutdown period, or if needed, lessening the length of time of a shutdown period. So should I leave my engine ticking over before it is turned off? The answer to that is dependant on how you drive. The Qashqai handbook states (although it discusses diesel engines, the same can be applied to petrol turbo engines): [quote"]]To ensure prolonged life and performance of the turbo charger, it is essential to comply with the following maintenance procedure: * Change the engine oil of the turbo charged diesel engine as prescribed....* Use only the recommended engine oil....* If the engine has been operating at high rpm for an extended period of time, let it idle for a few minutes prior to shutdown* Do not accelerate the engine to high rpm immediately after starting it"[/quote"]] So using the above information, we can summarise and make a quick "what do I do" guide... Driving 'normally' with light loadThere is no need to allow your engine to idle before shutdown. However, if you wish, a 30-60 second idle period before shutting off the engine will do it no harm. Driving "with a heavy right foot to the drive way"Yes, you should allow the engine to idle for a short while. Handbook suggests "a few minutes", but that depends how hard you have been driving. A better way to deal with this is to drive sensibly for the last mile of your journey. This allows air to pass around the engine, and give the cooling system a time to remove excess heat more efficiently. Driving with large load (such as towing a caravan, just driven up a steep hill in a low gear, or a car full of people and a boot full of luggage).If you have had to drive your engine hard, then your turbo will have also taken quite a pounding to ensure power is available. It would be a good idea to allow your engine to idle for a short period before shutting down regardless if taking it easy. This of course is an my personal interpretation of the handbooks suggestion of "idle for a few minutes if operating at high rpm for an extended period", and my own knowledge of turbo's. It is your own call to make up your own mind as to how you would like to handle shutdown of your engine. If you prefer to err on the side of caution, then a shutdown period of 30-60 seconds will do no harm regardless of driving style.

SplanK2014-09-20 11:07:59

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