Turbo cool down time

It’s a question I get asked all the time. “Do I need to let my turbo cool down after driving?” To answer this we need to understand the difference in cooling an engine and cooling the turbo on it.

Modern Diesels are all water-cooled. They have a fan that varies in speed dragging air through the radiator. Regardless of road speed the hotter things get the more the fan helps to keep the cooling system working. Stop the engine and the cooling system effectively stops being cooled. If you measured the water temperature with an external gauge at this time, you might see it continue to go up a little before dropping as the engine naturally cooled. Remember the engine is cooled by the cooling system.

The Turbo on the other hand is not cooled as such. It might be a water-cooled type but this isn’t cooling the hot exhaust housing. The turbo is designed to be part of the hot exhaust system and so is very durable to heat. In particular, the exhaust part of the turbo is designed to get hot. Since exhaust gases keep it hot, it’s only logical that once you shut the engine off the turbo temperature can only cool down, unlike the cooling system on the engine.

So in summary ALL engines with a cooling system need a cool down after long sustained full load. This means everyone towing or running fully loaded.  Once you shut the engine off, the engine cooling system will continue to get hotter before it cools down. By nature of backing the foot off a few kilometres before you stop is the best cool down you can give it as you are still moving with lots of air going through the engine bay.

‘So…do I need to cool down my turbo?’ Not really….but you should consider next time to cool down your engine before stopping after heavy towing.

Safe Driving!

Andrew Leimroth 
Berrima Diesel