Got a 00 XJ 4.0, I've replaced the water pump 3 times since May. I have been using carquest pumps (I know now they're junk) but everytime it has leaked out of the weep hole after ~1 month of being installed. Clutch fan is fine has no wobble/play in it, and belt tension is as my Haynes manual recommends. I replaced the thermostat in May as well, and cannot seem to figure out why I keep going through pumps. I bought a FlowKooler and plan on installing that tomorrow, and suggestions of what I should change this time around? I'm stumped.

Were they reman units or new? I learned to do water pumps on a 79 dodge pickup I drove in high school....after the third faulty reman, my dad suggested I spend the extra $15 on a new one. It worked for the rest of that truck's life and now I always buy new. Never had a problem again. Sounds like you had a run of bad luck with crappy water pumps. The flowkooler should fix you up.

They were reman'ed. that could have been the problem, I had the same brand the first 2 times but this most recent was a different (still crappy) aftermarket brand. Really hoping the FlowKooler does the trick.

R u running straight water? Water has no lubricant which will cause seal failure (even in a FlowKooler) in short order.

Belt to tight ?

Also make sure the pump is the right part and rotates in the correct direction.

I was running prestone 50/50, I thought maybe the belt was too tight but it deflected 1/4"-1/2" when I measured it. I did it a little bit looser today when I installed the flowKooler, hopefully I won't have to do it again for a few years. Thanks for the help all.

Definitely blame the reman pump there, usually not within specs from some of the original parts being worn and causes seal wear or imperfect sealing surface.