i've got a 1991 cherokee 4.0, ever since i,ve owned it it always runs hot in the summer (anything over 80).

Did you replace the radiator hoses when radiator work was done? See if you can pinch the bottom radiator hose shut. If you can, it's bad. I would change over to electric fans. They don't require any HP. to run. Also have you changed the water pump? Impellers could be worn!

I have a '93 Grd Cher 4.0 and it used to run hot frequently. I put a Flow Cooler water pump on it and a Flexilite Black Magic electric fan. I have never had a overheating since. (FYI some 4.0 Grd Cher came out of the factory with the wrong fan blade on them. I was at my mechanics shop and he was telling me about this other customers Grd overheating. He had tried everything. I had a look and noticed it had a smaller fan blade. Thinking my trailer towing package had a better fan, suggested trying a fan like mine had before I changed it. The Jeep dealer said the Grds all used the same fan. We found out the factory had installed a fan for a Cherokee which also used an auxiliary electric to supplement cooling. I heard the correct fan made a big difference.)

how long will take for the water-pump blades to rust away? I have seen 3 or 4 people find this to be was wrong with 4.0 motor I just got one was sitting 3 years do think in this time? this be is wrong my jeep it has a 3-row radiator, and 3 x 10" Fans! had a plugged up upper hose I fixed it but the temp gauge going up to 220+ for a short time goes down to 195d. before was losing water but not now why? Had I XJ's years never had heating problems after going to a better water pump? I think this answer see I was told a new water-pump was put before it sat for 3 years? can the impler rust away in just 3 years?