Bought a 97 Cherokee from my boss took a while to get it running when I did it did wonders but recently my radiator crack put some jb weld just to get me by. After that I have a major leak of coolant from behind the harmonic balancer but i have no idea where to start fixing it or what should I do first

 

Look above.....

 

x2 on what Cruiser said.

If you weren't aware, a failing water pump will start to leak coolant out the weep hole and that coolant will run south. You can get a pressure testing loaner tool from Autozone and pressurize the system - it will make any external leaks very obvious as to where they're coming from. It could be a simple as tightening up the hose clamp seen in Cruiser's photo.

On a side note, I wouldn't put off replacing the radiator properly. A lot of folks on here have had good luck with the Autozone special cheapos.

 

Teyomf upload the picture but won't let me it leaking from the front. Like if your look at the front plate it got some kind of rubber seal I guessing

 

If it's behind the harmonic balancer it is most likely the water pump weep hole like PAtHenry suggested. I bought one of the spectra premium radiators from advance for my YJ. It has been great. If anything, it cools off too quickly when I park in the winter. I would not mess with JB weld on a radiator on a cherokee (or any car). When coolant goes, bad things happen quickly.
I bought a '98 cherokee with a blown motor. When I pulled it apart to see what happened, the thermostat had rusted shut. the PO had used well water. It overheated and blew a hole in 2 pistons and destroyed the cylinder walls.
A radiator replacement on a cherokee is really simple. Burping the cooling system is a pain. Replacing the water pump at the same time is not much more effort. Change the thermostat while there too.

 

X2. Do it right. Radiator, water pump, hoses, and thermostat. On the t-stat, spend the extra money and get a Mopar.

 

x3 - Shouldn't cost much more than a couple hundred bucks and a few hours of your time.

 

On the t/stat, I've used Stant Superstats my entire life and never had one fail. Good value from the price. They open gradually so you don't get that rush of cold coolant into a hot motor.