Is this the right part number coolant cap?

[Boxtaboy]

It could very well just be the cap. For a period of time, I had a small bit of condensation showing up under the trunklid of my car, right above the coolant cap area. This eventually led to the coolant level to drop 1/4 in the reservoir.

I thought it was a problem with the bleeder valve, but after looking at it and seeing no coolant residue down there, I simply opened my coolant cap, and reseated it very tightly again. No more coolant condensation on my trunklid, and no more drop in coolant levels.