Don't bother with penetrant, PB blaster, Etc. those are designed to loosen fasteners that are frozen from things such as rust etc. What you have is known as galling. It's very common when 2 dissimilar metals ie aluminum and steel seize to each other. It can happen at anytime if installed dry. Sometimes I will be sliding a compressor onto a shaft and if Im not careful if will gall to the shaft with little to no warning and I have to press it off taking a bit of the aluminum with it. The only thing that will help is heat and patience working it back and forth and even then expect to have damaged threads in your head. Use heat work it back and forth and be patient. Worst case is you snap it. Then you are in a real mess. Try to work it slowly and then you will have to clean up the threads once you get it out. Anti-seize compound will eliminate this problem in the future.
Vargas Turbocharger Technologies
N55 World Record: 477WHP / 509WTQ, 11.4 ET / 123MPH
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