Blown Head Gasket or Cracked Head??

It just started recently that my temp will climb rapidly and go all the way into the red. When it gets close to the red I start hearing clinking noises that sound like detonation. Also, smoke will start to come out from around the valve cover and out the oil cap hole if I take the cap off. Is my head gasket blown or is the head cracked??

My Jeep is a 97 4.0 and I recently put in a new 3 row radiator and the temp has been constant at just a little above middle. Before the new radiator, however, it would always run a little hot and occasionally overheat.

Please let me know what you think it may be. It is my DD and I am still driving it about 7 minutes to and from work.

Any help would be greatly appreciated.

If you are running it in or near the red it is over heating. All of what you said is common of running an over heating vehicle. Just don't do it and you won't have those problems.

X2 - you are just making things worse. You won't be able to tell if your head gasket is leaking or head cracked until you pull it. Are you using a lot of coolant? You can do a compression test or put a pressure tester on the radiator and look for the pulses from the cylinder compressions.

Well it abnormally speeds up from the middle to all the way red.

Another thing I forgot to mention is that my radiator cap does not stay on as tight as it should. Could this be another reason? Is my water pump broken maybe?

Since you replaced the radiator it could be your water pump or t-stat. If your radiator cap isn't holding pressure that is a problem too.

#1 thing to do is to be sure that your radiator cap seats "tightly" on the radiator. Can't go further with diagnosing this until that is sealed properly. Basics first.

You have problems, and it ain't going to be cheap.

Hard to diagnose, but crack is unlikely(unless someone put a 0331 on there)