2 weeks ago, my front crossover pipe collapsed internally, and had to be replaced. From the cat-back was replaced 2 years ago (cat is gutted). Now that they've replaced the crossover pipe (about 2 1/2 feet worth) with single walled pipe, the car is now overheating! I'm stumped. NOTHING else was changed. That car always ran fairly cool, only sitting in traffic would cause it to go to 220, and then the fan would come on and cool it back down again. NOW, its running 15-20 degrees hotter than before, it was running 200+ going down the highway at 65 on a 65 degree day! The engine was replaced several years ago, along with the water pump, radiator, hoses, etc. Air dam is in place and functional. ALL we did to the car was replace that crossover exhaust piece. Why on earth should she start over heating now?

 

ttt - wow - no ideas???

 

have you verified that the fans are still turning on?

 

yes. Fans are turning, coolant full. no leaks, nothing obvious.