Strange Sound When Starting

[Believer]

Once in while when starting, I get a very loud sound that I can only guess is coming from the turbo. Lasts about 3 seconds. It's not a starter noise, more like something spinning very fast. Happens infreqently. Any ideas?

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94 2500, 250/605, BD Exhaust Brake & 60# Springs (not installed), 19. 5 Michelin XZT's, 2" Skyjacker, DT Control Arms & Trackbar, ARB locker front, Reunel & MileMarker Winch, B&W Turnover Ball, Firestone Bags, PrimeLoc.

 

[JohndeereG]

Is this sound during cold weather startup. There is a power steering fluid by-pass which allows the fluid to warm up first. My rig will occasionally get a humming sound.