So I bought a 2003 TJ Sport 4.0 5spd from a college girl. 110k miles and stock, minor rust. she had only driven it very short trips for the last 4yrs and had it maintained regularly. The shop was fairly aggressive with her checkbook, so I have a new clutch, brakes, tires, etc.
I noticed that the water temperature (scangage) creeps up on longer rides of over 20min, peaking in the 230s. The coolant looked good, so I swapped the radiator cap & thermostat hoping to get off lucky. No real change. I bit the bullet and ordered Mopar radiator and Water Pump. While awaiting shipment, I pulled the thermostat and put in distilled water for a flush. It seemed to be slightly better, but would still gradually increase on longer rides. I decided to try Thermocure flush. I drained the old Distilled water to make sure it was clean (it drained clear), then filled it back with Distilled water and Thermocure. I ran several trips over a couple of days with the same temps. Then started the drain&flush sequence because the radiator & water pump arrived. The first flush was black and it took at least 5 sequences of flushing to get it back clear. An interesting note, after the first flush, the water temp would shoot to 250+ within 5min on the road and I would have to turn on the heat and blower on high to limp home or park it to cool down. I suspect a combination of radiator blockage and improved heat transfer from the block to the water was the culprit.
Once I got the new radiator, hoses, water pump, thermostat, and 50/50 G-05 installed, I did a 1hr loop through the hills with about a 1000’ elevation change. The water temp stayed 190-195 (with a 195 thermostat). Even with the AC on full blast it stayed at 195. I am happy.
All things considered, I probably could have skipped the water pump, but now I know it is right.
I noticed that the water temperature (scangage) creeps up on longer rides of over 20min, peaking in the 230s. The coolant looked good, so I swapped the radiator cap & thermostat hoping to get off lucky. No real change. I bit the bullet and ordered Mopar radiator and Water Pump. While awaiting shipment, I pulled the thermostat and put in distilled water for a flush. It seemed to be slightly better, but would still gradually increase on longer rides. I decided to try Thermocure flush. I drained the old Distilled water to make sure it was clean (it drained clear), then filled it back with Distilled water and Thermocure. I ran several trips over a couple of days with the same temps. Then started the drain&flush sequence because the radiator & water pump arrived. The first flush was black and it took at least 5 sequences of flushing to get it back clear. An interesting note, after the first flush, the water temp would shoot to 250+ within 5min on the road and I would have to turn on the heat and blower on high to limp home or park it to cool down. I suspect a combination of radiator blockage and improved heat transfer from the block to the water was the culprit.
Once I got the new radiator, hoses, water pump, thermostat, and 50/50 G-05 installed, I did a 1hr loop through the hills with about a 1000’ elevation change. The water temp stayed 190-195 (with a 195 thermostat). Even with the AC on full blast it stayed at 195. I am happy.
All things considered, I probably could have skipped the water pump, but now I know it is right.
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