Pitting in coolant passages

[slipnfall]

Hi - I noticed in a couple coolant passages there's a good deal of 'pitting' in the aluminum. Some are a good 3mm deep. The majority is around the water pump flange(towards the inside of the mating lip). It doesn't look like enough to cause a leak, but I wanted to ask anyways. I'm guessing this is normal, but am curious as to it's cause. Did debree stick here and create hot-spots of sorts? It looks like a chemical deteriation(discolored metal).

-Slip

[s13sr20chris]

that is typically due to improper mix in the cooling sys. may have been a lack of coolant changes or bad coolant. rtv is good for filling holes.

[slipnfall]

Ok, gotcha. Well if anything that's a testiment to keep good care of it. My stock rad. was corroded badly at the bottom, which may explain a thing or two.(add that to the list of things to buy...)

Factory is single core, right? I see a Koyo or two on ebay for dirt cheap.($170 shipped?).

Thanks for the info!-Slip