I removed one of my AL water blocks a while back and replaced it with my REV. 2.0 copper block. I took that AL block to work to day to clean it out and sand blast it. Once cleaned out I noticed BAD corrosion on the top and the base. Almost all the way through on the base.
Will post a pics when I can. This is a case of the battery effect plain and simple. That's what I get for useing brass barbs with a AL block. I only used it for less than 2 months 24/7!
I am sure this can be prevented by not using brass barbs, and better anti-corrosion stuff. And better yet anodizing (which isn't an option). I just used windshield washer fluid.
Anyway, I am moving on to Copper. Going to beef up my mill and use my drill press to make Copper blocks from now on. Just as well anyway. All the heater cores I use are brass and the barbs I use are brass. Just aswell make it all get along. If I waited another month I may have had a serious leakage problem through the base of that block!
After my cable internet gets hooked up today I am going to remove my aluminum Lemon Block and replace it with either a Copper block or just an air cooler for now. I have a decent Copper block made up, but I just need to make a new top for it.
Would be advised to check your AL blocks now and then if you a running one!