Bear in mind our car is a 6 not a 4, but hot weather problems seem to be a shared issue. Our car has the van shroud extremely close to the firewall, in fact we actually cut a portion of the fire wall out to accomodate the fan (then made a cover for it).
We were having heating issues in the hot weather. Contrary to popular belief, all of Oregon is NOT cool... We've been over 100 degrees almost every day the last couple of weeks. The car seemed to maintain acceptable temperatures 180-200 around town unless you really start pounding on it. Then it would climb to about 220 and we'd find a place to shut her down. Oddly enough, once you held the speed up above about 50mph, it would get hot REALLY FAST. We decided the problem was air flow to the fan.
I think Steve fixed this. He bent a piece of sheet metal to form a diverter under the belly pan up to the front of our engine. It only extends down about 1 inch, but it is very wide. This pulls air up to the front of our engine where the fan can get to it. I believe it solved the problem. I drove the panties off it yesterday and couldn't get it over 200 (and the air temp was 100).
angela