My 99 4.0 I-6 just started overheating when I was driving one day. 2 months before i installed a new water pump and the thermostat is working. when i got home the coolant resevoir was empty. The engine has 190,000 miles. I was wondering if the problem could be the head gasket, and also if i was driving and the temp guage redlined three times( i pulled over immediatly and let it cool down) if there could be any other damage to the other engine components, like the pistons. Thanks

You will have to drive for extended time to "cook" the engine. You have to find leak first and fix it.

Have you put pressure on the radiator to check it? Seems simple but that was my problem.

Thanks for the reply, I was just wondering what ended up being your problem after you put pressure on it? Headgasket?

I actually had a small hole in my radiator so fluid wouldn't leak unless I was driving so I never saw anything underneath the car. I replaced the radiator and no problems since.