TJefferson2020

surprised at corrosion!

Mikado463

not the kind I like to 'nibble' on !

TJefferson2020

I'm hoping it's just the zinc finish on the nipple and not indicative of internal corrosion. Coolant looks brand new (since it sprayed everywhere when I pulled the hose...)

Anything to be concerned about or normal?

skeew

Perhaps Galvanic Corrosion...google it.

Aluminum intake - steel nipple

Brian VH McHale

Just a blue box, has something changed?

PaulUptime

One of my first real challenges was exactly like that, but it was a steel hose nipple on a cast intake, so don't think it was a galvanic issue in my case. I too was shocked at the corrosion and was nasty to remove as it just crumbled around its rust locked threads. No amount of heat, penetrating oils, patience or effort could get it to budge. But it had to come out as it could also no longer support the hose I wanted to attach.

I didn't want to pull the intake so stuffed paper towel into the hole, then broke it away until I could pry it away from the threads, shop vac'ing away all the shrapnel I could. Today, I'd just pull the intake and do the whole thing off the engine.

Frankie the Fink

To go a bit farther on Paul's idea...

You could try a paper towel slathered in wheel bearing grease partially stuffed down in the nasty orifice...clean things up as much as you can around the circumference and the grease-laden towel should catch all the crumbs and you can carefully pull it out and see if that is good enough to satisfy you..

Easy Rhino

Your cooling system has lots of dissimilar metals (iron, brass {copper/tin} aluminum, tin, etc.) in it, with different oxidation potentials, all in contact with a reactive solvent - water. That's the recipe for setting up a galvanic cell - aka galvanic corrosion.

Be sure that you keep fresh anti-freeze in it, that is, without the corrosion inhibitor not depleted. Your anti-freeze hygrometer does not test for this.

If you want more help, you can buy sacrificial cathodic zincs to install in the cooling system.