How should I make sure my turbocharged engine cools properly when I switch it off?
You often advise about cooling down turbos before switching off the engine. I have a TC petrol engine and during normal driving the oil temp rises to 94/95C. What temp should it drop to before switching off to stop the oil carbonising?
Petrol turbos are invariably watercooled and proper installations have a separate pump to continue pumping coolant through the turbo after the engine is switched off. So a turbo overheating is only likely to be a problem in extreme circumstances, such as after circuit driving, after a long ascent or after towing when it's still wise to leave the engine idling for a couple of minutes before switching off. It’s also sensible not to switch off straight away when stopping for fuel on the motorway. The oil temperature gauge alone does not tell you the temperature of the oil in the turbo.
Answered by Honest John on