My KK is giving me fits at the moment. I have 2 seemingly unrelated problems at the moment, but maybe they could be related. Hopefully somebody knows.

I've been having warm start issues. Sounds like the trucks flooded. I turn the key and it cranks but won't fire up (i've made other posts about this). After a few tries and pressing the accelerator to the floor the engine will come to life. I'm assuming at this point that is a leaky fuel injector. This problem needs to be dealt with but as of Thursday the jeep started to overheat in traffic (climbed to 3/4). Now I had this issue a few months ago and I replaced the radiator and the water pump and that seemed to fix the issue. Fast forward to now and it's happening again. I got it up to temperature and I looked under the hood and noticed that the radiator fan wasn't working. I cranked the AC and still nothing. So, I thought I should replace the fan, so I did that yesterday. Went to drive it today and the temp gauge wasn't moving and I got the little electric bolt with 2 lines CEL light, so I thought I hadn't plugged something back up, so I pulled over and cut the car off. I cranked it again and that light went away and my temp gauge was back to life sitting at 1/2. I drove for a minute longer and found a parking lot and the darn temperature started climbing again! I'm at my wit's end with this thing. The only thing I can think of would be the coolant temperature sensor. I think it's been known to spark the lightning bolt CEL and would explain my temperature issues, right?

Does anybody have any other ideas? Bonus if you can tell me if this might be causing my hard starts.

A little update:

After doing a bit of research, I decided to go ahead and switch out the coolant temperature sensor. The new sensor was really snug fitting in and didn't go in quite as far as the original. I searched high and low to see if I should grease the threads to go in more smoothly, but couldn't find anything. If anybody has any insights on that, I'd love to know.

Anyway, I cranked it up. Still struggled a little bit so that was kind of a bummer. I drove to a local grocery store to warm it up and sat in the parking lot to see if the temp climbed. And climb it did. I sat there for about 6 minutes and the temp climbed from 1/2 to 3/4, but it never pinged the temperature dash light which it normally does. So, I don't know if I fixed it or not. I don't think I did. Lots of weekend work and money spent and not a whole lot of success. Where did I go wrong? What else would you guys try? I'm all out of ideas. I guess my next step will be forking out big bucks to a mechanic.

Did you ever replace the engine thermostat?

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U.S. Army Retired

Not yet.

Did you check that the fan is working? and that there are no leaks in any of the hoses? Any leak in the system will also cause cooling problems. A bubble in the cooling system will also prevent good system cooling. This could also be a leaky/cracked head.

Be careful when working in and around a hot engine, my mechanic got burned really bad when a hose burst while he was working under the hood of a British sports car.

Good rubber hoses should feel like the tread on a new tire if you stick your thumbnail into it. Stiff and the rubber rebounds quickly. Bad hoses feel crunchy and your finger nail won't rebound with a good force.

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2002 Liberty Limited
2.5" Rusty's Coil Lift + OME 927 springs + 1/4" spacers
265x70 Revos
Warn 4x Floods
ARB bumper
TeraFlex extended front bumpstops
Rock Lizard Skink Super Sliders
Bosch Size 86 battery
Jeepin by Al's 4.5 UC Arms
Kryptonite Differential Cover
JBA Bolt on KJ Tri-Angulated 4 Link

I would check the oil to make sure there is no coolant getting into it. That sort of thing would be a sign of blown head gasket or damaged head. Otherwise definitely try the thermostat!

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04 KJ Sport:
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K&N FPIK, Fastman Throttle Body, 4.10 Gears, B&G PCM Tune, Hyperutetic Pistons, 50 HP Wet Shot, Lots O Fun!
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