I have a 2005 chevy trailblazer that overheats. I can run it for 20 minutes with no worries and then sometimes it overheats quicker. I don't see any leaks in the radiator and the water pump is new.

I was thinking head gasket but the oil in fine and there is no white smoke exhaust. There is a smell of gas in the coolant tank.

Would a broken camshaft sensor cause this? I know that sounds like a NO but i have to ask because mine is broke off the engine.

Someone told me with the cam sensor broken then your timing could be Off considerably. Also that could mess with fuel trims and the PCM could be dumping fuel in the motor.

I had the radiator cap opened and i ran the truck with the cap off for about 6 minutes, i can see bubbles in the water. It's like someone inside the engine blowing bubbles back at me.

Any ideas how to know for sure?

Thanks
Bryan