White build up in a brand new aluminum water neck

[crm318]

I just installed a brand new aluminum thermostat housing on my 350 and after replacing the crappy gasket it came with, I noticed a white mushy film coating the inside. It's only in the housing and not in the radiator hose. It washed off easily and there is no real signs of pitting. It has to be a chemical reaction with the aluminum. Does this mean the coolant ratio is off?

[mongocanfly]

most likely oxidation...did you use distilled water in your system?...
http://www.aa1car.com/library/coolin..._corrosion.htm

[crm318]

That is probably my issue.

[68gmsee]

Aluminum reacts with certain chemicals in the coolant. I've had bad luck with aluminum t-stat housings corroding before and usually wind up replacing them every couple of years or so.

[Ironangel]

Make sure you have good clean grounds from the block to the cab, block to battery, as well as cab and bed to frame. Sometimes the pot metal thermostat housings act as an anode and will deteriorate quickly. Using hard water in your coolant system promotes the electrolysis effect.

[68gmsee]

Originally Posted by Ironangel

...Sometimes the pot metal thermostat housings act as an anode and will deteriorate quickly. Using hard water in your coolant system promotes the electrolysis effect.

^ This year I learned another thing about dissimilar metals and water. About 4, 5 years ago I had a leak in my galvanized pipe water supply line to the house. I spliced it and used a brass coupling on the line. Earlier part of this year I had another leak and found the brass coupling had corroded enough to create a leak. Apparently brass and galvanized metal don't get along where there's water involved.