2001 Nissan Xterra • 150,000 miles

This car overheats while climbing a hill on freeway, while driving around town no problem.I did the head gaskets last nov. While this problem just started. Its a v6 with ac, autotrans. The rad is approx 2yrs old. Since the heating problem i've put a new stat, a new fan clutch, new rad cap.I did a block check plus took it to a rad shop and they did a blockcheck and found nothing in fact they are scratching there heads?I work in the auto industry (for chevy)and have asked everyone.I hope you can give me some ideas as this is my daughters vehicle and a want my wheels back. This seems to be a stumper! Thanks for your time.
June 27, 2012.

Trans fluid would not be sufficient to heat the coolant till it overheats as the cooling system should be able to take care of that.

What you have is inefficient cooling due to excessive strain on the engine and the only way you are going to resolve this is to get a bigger capacity radiator.

Jul 25, 2012.