temp sending adapter

[Llay R. Rac]

5 months ago i put a new stewart warner mechanical temp gauge in my truck. I haven't driven the truck since, i have idled it about 2 hours total.

today when putting in a new water pump, i pulled the thermostat to block housing and i noticed a large amount of white crumbly stuff growing from the area where the adapter for the probe meets the block. It had almost encircled the lower half of the probe. i didnt think to take a picture.

I am sure this is corrosion, the adapter, from the s/w kit, is plated steel, the housing is the original steel housing, so how do i get so much corrosion so quick and how can i avoid it.