I just cleaned much of my engine compartment with Abro Heavy Duty Degreaser, and I noticed that on certain metal parts like the valve cover, thermostat housing and transmission housing a white powder has formed:
I left the degreaser on for maybe 30 seconds to a minute, and in some cases agitated it with a brush, then pretty thouroghly rinsed it with a water hose.
This powder won't blow off, but it rubs off pretty easily with my finger as can be seen in the picture. This did not occur with other metal parts such as the engine block, and various metal pipes and connectors, nor did it happen on hoses or painted parts. I think the parts it did happen on may all be made of aluminum.
- Why did this happen?
- How can I easily clean this?
- How can I prevent this from happening in the future when I clean?