If the thermostat is bad then it would overheat the car. I replaced mine when I did the oil cooler swap couple years ago.
Okay. Replaced the aux water pump. Works just fine and doesn't get hot. $130 later...this car is not for the feeble minded...or the big handed or broke college students.
It is. I got mine from dealership for 5k cash with 126k in excellent external and internal condition and put in to it so far 6k in 4 years. I have now 158k. And I did all work by my self. I learned so mush from my car, it gave me experience that u can't find. I love it. I will keep it until my engin die or tranny and if it's happend, I will swap it.... I still have OEM floor mats :)
Oh, and does anyone know of an all aluminum replacement radiator for the Catera?
There is thread here, How to replace radiator. Search !!! . They way cheeper if u get it of online, like eBay or rockauto. I got mine from junk yard for $40, work just fine. It's not that easy to replace but not to hard and no special tools needed so that's good.