Small leak can cause air ingestion.

bringin it back alive:

so there was some serious missing coolant and I temporarily filled it up with water until I get a chance to flush the thing.

and I noticed a little dribble of water from the bottom of the radiator drain plug. I dont know if that's where it's coming from because it's the lowest point, but it's pretty minor I think.

next question: anyone know a good place to get an aluminum koyo radiator fixed up to patch leaks in northern virginia?

Anyone who can TIG should be able to patch it up.

I FOUND IT.

it isn't the radiator--technically. The drain plug failed. Not sure how, but it's plastic and I guess heat cycled or something. Or I overtightened it (hard on a philips head drain plug like that).

When I tried to pull it out to drain the rad, it just broke into pieces. I had to drill it out.

So I replaced it with a bolt and some silicone hose to make a compression gasket. Hopefully it wont leak now.

lame!

my drain plug leaks slowly, i really need to fix that shit.

#10 flange head bolt and some 10mm silicone hose about a half inch long.