I guess the first step would be to check if there's coolant sitting in the valley to begin with - maybe stick a hand pump vacuum hose down there & see if sucks anything up? That whole thing is so buried! I know when I was putting my top end back together, I tried my best to make sure that that heater pipe o-ring was seated & sealed right 'cause going back at it would mean pulling the plenum.... <img src="/forums/images/graemlins/frown.gif" alt="" />