A question I get asked a lot is should you let a turbo car warm up and cool down before driving it? And if so, how do you do it? Well, the answer is simple.
If the ambient temperature is below freezing you should let your engine idle for 60 seconds, if the temperature is above freezing you should let the engine idle for no more than 30 seconds and then drive at a moderate pace until the engine reaches normal operating temperature.
Allowing your engine to idle for 30 seconds will give the oil time to circulate through the engine and lubricate the turbo, this will avoid any damage to the seals or bearings of the turbo which need lubrication to allow rotation of the turbo to happen freely.
Car manufacturers do not recommend leaving engines idling to warm up for prolonged periods because it can damage the catalytic converter and diesel particular filter (DPF) in diesel engines. Thirty seconds is about the time it takes to put on your seatbelt and settle into the car.
The only times it is necessary to cool down a turbo is after a high mileage trip or after hard driving at high RPM and the turbo gets very hot. To cool down a turbo you simply leave the engine idle for thirty seconds before switching it off, this is especially important if you have a ball-bearing turbo.
Why Do Turbos Need to Warm Up
It’s not so much the turbo that needs to warm up, instead, it’s the oil that lubricates the turbo that needs to warm up. This is because when you first crank the engine the oil is cold and thick sitting in the sump, once the engine starts the oil pump needs to suck up that thick oil and push it around every port and oil gallery in your entire engine and turbo.
Because the oil is thick it is harder to push around the engine and may not reach everywhere instantly, meaning it is not lubricating the engine and turbo as effectively as it should. This is a common cause of turbo failure due to bearings being spun dry and seals being worn because of the friction generated from the components spinning at a high rpm and overheating.
Allowing the oil to reach normal operating temperature in a journal-bearing turbo is crucial to prolong the life of the turbocharger.
Journal-bearing turbos need to warm up because instead of using conventional bearings it instead uses a layer of high-pressure oil which allows the turbine shaft to float and rotate freely inside the turbo housing without generating friction or heat.
If the oil does not reach the working temperature it will not create the correct oil pressure in the turbo and the thin layer of oil which the shaft floats on will not be adequately balanced or lubricated meaning premature turbo failure may occur, that’s why it’s important to follow the correct warm up and cool down procedures.
Why Turbos Cars Need to Cool Down
The reason you need to allow a turbo car down is to allow the oil and water to continue to circulate around the engine and turbo which allows the heat to disperse gradually and evenly.
By leaving the engine to idle before shutting it off you allow the oil to continue to circulate through the turbo, by doing this the oil can actually pull the heat out of the turbo and replace it with cooler oil.
If you shut off your engine straight away all the hot oil inside the turbocharger will stop circulating and sit in the bottom of your hot turbo, this oil will then turn on to the inside of the turbo like butter on a hot pan resulting in the turbo becoming coked and rough.
This is a major problem and a common reason for turbo failure in a ball-bearing turbo because once the inside of the turbo becomes coked the bearings can no longer spin freely and causing the bearings to skid rather than spin.
Once this happens the life of your turbocharger is significantly reduced and will need to be rebuilt or replaced pretty soon after. To find out absolutely everything you need to know about how a turbo works you need to check out this article.
Since the invention of the first turbocharger in 1905, the automotive world has never been the same again, due to the immense amount of power a simple turbo can add to a combustion engine. But since...