Hi everyone when I bought my jeep the previous owner told me that the jeep had 3 issues. 1. The 4x4 makes noise. 2. The serpentine belt likes to come off and 3. the jeep sometimes overheats.

On my test drive I found out the noise was coming from the aussing D30 locker so no big issue. On our drive home it did overheat so I pulled over and let it cool down. Kept driving it home but now had the A/C turned on and no more overheating issues but the A/C would cut off at higher RPMS.

A week after I got it home I changed the following items. spark plugs, wires, thermostat (fail safe), water pump, radiator, serpentine belt. Jeep would run right at the middle of the temp gauge but would go up at highway speeds but not to the point where it would overheat. So we took it to San Diego for some fun and it ended up almost at red before I shut it down. Jeep lost all oil pressure and would knock when ever I gave it gas. Once it cooled down everything was fine.

Got it home changed the thermostat freaking fail safe sucked made the mistake and put another fail safe in there and jeep ran the same. auxiliary fan will not turn on its own unless I turn on the A/C is this normal? A/C cuts off at higher RPMS. I also added hood vents to see if that would help.

Took it to Big Bear and the jeep wouldn't want to go up the hill felt like it had no power, temp would go up to red. No oil pressure. Finally made it up the hill and it off-road fine until the serpentine belt decided to come off. Put it back on and drove down the hill.

Changed the thermostat again freaking fail safes stay stuck open when you overheat lol this time I used a regular thermostat and I changed my radiator cap I had a 13LB switched it to a 16LB. Did a compression test and all cylinders are between 160-170 changed the plugs while I was at it and I switched the oil pressure switch. After all this the jeep ran perfectly no more overheating on the freeway temp would stay right below the half mark.

Went to Big Bear again going up the hill same thing started to overheat, low oil pressure, no power and knocking sound as soon as I gave it gas. got it up the hill it ran fine off-road got it back to camp check it out and found the belt almost coming off. Also my clutch wont let me go into gear unless I double clutch something it wont let me at all.
What else can it be causing it to overheat? Ill be doing a super flush on the radiator and replacing my fan clutch with the zj one but cant figure out what else can it be. Can I have a bad oil pump causing the no oil pressure? too thin of oil? Whats causing my belt to slip off? Why is my A/C cutting off? I need help.

 

Replace every cooling system part. Radiator, water pump, hoses fan clutch. Everything. As far as your oil pressure issue. I am not sure on that issue. Could be numerous things

 

I've replaced everything except for the fan clutch