Is this going to be Equal to pounding my sack flat with a rubber mallet on a concrete block or somewhat worse?

 

Pound it flat using a meat tenderizer. That covers it.

 

If you don't have a meat tenderizer a fork will do. Good luck I've been "especially" avoiding doing mine.

 

I was about to post a pic of mine sitting in it's box....

 

It's easier to teach your **** to play the guitar than it is to change your heater core.

Not really, just thought I'd chime in. It's not that hard really, it is just very tedious and takes quite a long time, especially if you've never done one before.

Get a good procedure, some beer, and plan to change the air conditioner evaporator at the same time while you have things torn apart. Take your time and pack your patience.

I have had trouble with the cheap $75 Chinese heater cores. (very poor longevity). At one time, I knew of a vendor that sold a high end aftermarket heater core for about half what Jeep charged, but I can't locate that vendor any longer. Jeep cores are damn expensive, ($300+) but this is not a job you want to do twice. You'll agree with me after you do it once. I'd spend the extra money for a Jeep core if you plan on keeping your XJ.

 

There are worse ones out there, old 80s' K cars. Iacoca put those cores up and behind everything on the drivers side.