Overheating w/ Cold Radiator
I'm running out of ideas for my '99 Cherokee. It overheated on me during a highway trip a couple days ago. It had been idling a bit rough the past couple weeks (especially in reverse), but no indication it had been running hot. I pulled out the idle controller, cleaned, lubed, and replaced. Then replaced the thermostat. It sounded better when I cranked her up, so I took her for a test drive, only to overheat 20 minutes later. As it was overheating, there was a loud flapping, like a metal baseball card in a bicycle spoke, as I touched the gas. I noticed that even though steam was coming from the engine, the radiator cap was totally cold. A friend towed it home, I pulled out the water pump, which looked fine, scraped and replaced the gasket, and reattached. I then flushed the radiator, which consisted of me hosing water down where the radiator cap goes and where the top hose is connected (not sure if I'm doing that right.) Had plenty of water flowing out of the bottom hose, so I'm thinking there's no blockage. I'm just having a hard time understanding how the engine could get so hot, and the radiator be so cold. A friend suggested I get my head gasket tested, but is that my last hope?