I'm starting to think my Sportage might be running hotter than usual due to some problem with the engine.

What I mean is, maybe the problem is not the cooling system, maybe the engine is generating more heat than it should.

What could cause this?

Things I have already checked:

- Timing is correct
- Fuel filter and fuel pressure good (and not running lean)
- No blown head gasket
- No trouble codes and O2 sensors work fine

What else could make the engine run hotter than it should?

I'm getting really stumped here... Unless the Sportage just can not handle climbing hills at high RPM with the AC on in hot weather without heating up? Maybe that is just the limit of what this vehicle can handle?

The way I have been testing is I fire up my logging software that logs the temperature, and I turn the AC on and jump on the freeway. Then I drive at about 5k RPM in 3rd gear for about 3 miles, and in that time the engine has been heating up to 230 degrees and would keep rising if I let it. Then I turn around and head back home driving about 4k RPM in 4th gear home, and on this trip it will run around 220 degrees. Once I get off the freeway and the RPM lowers, it gradually cools back down.

I replaced the radiator and I also tried doing this test with:

RSG bumper
stock bumper
no bumper

The RSG bumper runs the hottest, followed by the stock bumper which runs a little cooler, and the best of all is no bumper, which runs a lot cooler.

I don't want to drive around with no bumper though <img src="/forums/images/graemlins/frown.gif" alt="" />