If the crankshaft pulley is moving around, the harmonic balancer is probably coming apart. The pulley part comes loose from the center section. If so, you will have to replace it.

 

The pulley part comes loose from the center section.

And when that happens, the pulley can wear right through the timing cover.

 

It sounds like you need to replace the harmonic balancer. Those do fail due to the seal in the HB and will cause noises and vibes. You can rent the tools for free to replace the HB at most auto parts stores such as AZ, O'reillys, etc..

 

Alright. I'll check that out!

 

Mmmm. I took a look agaaain, and realized it is the Waterpump pulley thats vibrating! Not the HB. Sorry, big mistake of mine.

So now Im wondering if should I take the pulley out, along with the fan and stuff, and maybe just put it back tightly. Im not having temperature problems, so I guess the waterpump is Ok so far. ?

I recorded a video of it, you can check it out here.
http://www.youtube.com/watch?v=f38AOevz-Vo

 

Your water pump bearings are shot.

 

Yeah. So I will take those parts out to exam that. You think will be enough by replacing the pulley? Or the bearing comes with the waterpump, so it will have to be the entire pump. (I love my TJ, and trying to learn he he)

Tomorrow I'll start working on it

 

You need a new water pump. The pulley is just a single piece of steel, so nothing to wear out on it.

Now is the time to flush your cooling system and replace the coolant as well.