I recently purchased an AAR Cuda. At time of purchase the hoses that attach to all aluminum parts were "ballooned out" at the hose clamps (see heater hose in photo of engine). When I disassembled the engine down to the short block and removed the hoses, there was extreme corrosion under all of the hoses connected to aluminum parts. The corrosion was white and crumbled easily when dried, almost like table salt. I completely flushed the block, hot tanked the intake, replaced the water pump and thermostat housing, etc. and didn't think much more about it. I just thought the prior owner never changed the coolant. After the engine was reassembled I ran it on an engine stand with clean tap water for coolant. When finished I drained the block and set the engine aside while I completed the restoration on the rest of the car. As it turns I had to remove the thermostat housing today and when I did, it appears the corrosion is back (see thermostat housing pic). What the heck is this stuff, corrosion? What could be causing it. The engine was run for 30 minutes on a stand, drained and what you see here accumulated in 60 days. Has anyone seen this before? What can I do about it? I need help on this one guys. Thank you.