Quote:
Originally Posted by redpoint5
I don't understand how turbos are hurt by shutting off the engine. Sure, the oil or water that cools it stops flowing, but so does the heat generation. Does a turbo continue to increase in temperature after the engine is shut down, and if so, how?
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The turbo's hottest part, the turbine starts to cool when the engine is shut down. But the problem lies in the turbine transferring heat to the center cartridge. When the engine is shut off, the center cartridge will no longer have nice cool oil and coolant to cool it.
When the engine is running the center cartridge will run around 220*F due to oil and coolant flow. The turbine housing always is transferring heat to the center cartridge. But with the engine off and no circulation of coolant and oil to pull away heat from the center cartridge you could see the oil film degrade at the turbo's shaft and bearing's, if the turbine reaches extreme temperatures from very high engine load, or not enough ignition advance.
This is one of my turbo's that had some heat issues. Plus you can also see some coking at the turbine's seal.