Okay, here are the symptoms up to yesterday. The TJ has been like this since I bought it in mid-June. I have zero idea as to how long it ran this way prior to my purchase. (It is a 2003 Sport 4.0L @ 147,000 miles.)
The needle would stay forever at just above the 210 dot, about a needle's thickness of black gauge face showing between the needle and the dot. This was when it was "cool" but after the thermostat had opened up.
From there it rose based on outside temps and how hard I ran the thing.
Generally, on the road I stay five over the limit. I usually am too gun shy to go more than that as my history of tickets is long and painfully expensive. I am now 48 and am usually not in much of a hurry. I leave early and usually am early to where I am headed. On really hot days I drive the posted limit. In the rain I drive below the posted limit, always.
At 60 mph on a hot day (about 100º with 90% humidity) the gauge generally stayed pegged with about a 16th of an inch of black showing between the dot and the needle. Not a lot, but a lot more than I want to see.
On the Interstate at 75 on a similar day it would go up to about 3/32" of black visible.
Yesterday it got worse. Not a lot, but it was noticeable. I did not drive for long and raised the hood and rand the heater for five minutes after I got home.
I tried to do a decent job with the Prestone Flush-N-Fill kit with a 22 oz bottle of Prestone AS-105 Flush & Cleaner. I followed the instructions, but on the water-only cycle, rather than do it three times I ran water through it while running for ten minutes.
Then I changed the thermostat. Perfect job, absolutely no leaks, the bleeder valve was centered at the top. (I had been hoping that the stat was the issue. It was from a cheap parts store and did not have the little air bleeder valve at all. I know that needs to be there and oriented properly, and the FSM clearly shows it in the illustrations.)
Then I slapped on a new serpentine belt. I filled the radiator with 5.5 quarts of Zerex G-05. Then I used the flush kit tee to hook up a hose (no back-flow prevention valve, just a hose) draped into a recovery bucket and started pouring in distilled water. I *think* I got in five quarts. Not sure. I was distracted at the time and now cannot remember. It was either that or one quart. DOH!
Anyway, I had problems getting the water into the radiator using the displacement method (gravity only, engine off). So after struggling with the water I turned on the motor and when the stat opened up I was able to get in a gallon plus. (Oh, heck, I can remember now. Yes, about 5 quarts of distilled with 5.5 quarts of HOAT.)
The water coming out of the heater hose tee was clear until about that last quart, when it became orange tinted, but just barely. I was using an orange Home Depot "Homer" bucket and the only way I could see the very pale orangeness was to lift the hose up above the top of the bucket to see the water with the cement as the backdrop.
This was a PITA as I was pouring water in as I was looking at the hose.
When the color started showing in the water I had my wife cut the engine. I capped off everything and then restarted and ran for like 10 minutes.
After it cooled off I added the bulk of the distilled that I had not been able to get in the radiator into the empty overflow bottle. I poured in just a bit of Zerex with that. (Distilled, maybe a quart, Zerex, maybe a half a cup.)
The gauge was pegged to dead center of the 210 dot. We let it cool again and then took a drive that covered downtown traffic, US highway and Interstate speeds. Up to 60 mph it stayed on the top half of the 210 dot, just about to goo into the black. At Interstate speed (70) It started running hot again, but not as bad as it had been doing.
When I got below 55 and turned on the heater it returned to 210 dead center in about one minute.
We went home and it sat for two hours.
Then I drove it to town on an errand, which was a two hour round trip.
On the way out, at 5:00 PM when it was still pretty hot, it ran with about two needle's thickness of black showing between the dot and the needle. I drove it at 60 on the dot for about a half hour until I reached the Interstate, where I spent about a half hour at 75. It rose maybe one more needle's thickness and stayed there.
At my destination I let is idle with the hood up and the heater on. The temp ROSE after I turned on the heater. Then it came back down after like three or four minutes, back to 210 dead center.
I stayed for supper and drove home in the dark. It was nice and cool, in the 70s, and I stayed on back roads and US highways all the way home, avoiding the Interstate. It never left the 210 dot. It moved around within that small space a bit but never once crossed into the black.
Okay, that is 100% of what happened.
Now, we have a flush of dubious quality, maybe adequate, maybe not. But the water ran very clear, so whatever.
We have what is probably a good mix of HOAT and distilled water.
We have a new thermostat. It was installed properly and there are zero system leaks. The heater hoses both are very hot to the bare hand, as is the top hose. The bottom radiator hose is just barely warm.
The heater blows VERY hot.
The symptoms seem like it is cooling very well but cannot handle the Interstate on a hot day.
I will be changing the water pump and fan clutch tomorrow with dealership parts. (Yes, my butt hurts where they bit it with the prices, but the AutoZone parts both looked pretty poorly cast and assembled. I returned them and spent the bucks for the real deal because I cannot afford to trash another engine due to excessive heat like I did my poor, dead 2.4L SE.
If this does not fix the problem then it has to be the radiator.
Keep in mind that the radiator took TEN MINUTES to get 5.5 quarts of straight Zerex into the empty radiator with the motor off. And I could not get any water in until I started it up. Is this normal, or is it a gunky radiator? Should I fill it with some witch's brew and cap it off while I do the fan clutch and water pump, letting it "soak" in the stuff for a while?
Or do these symptoms sound like a fan clutch that is starting to give out, or a water pump that is underperforming?
I know it will get sorted if I throw enough money at it. But I do not want to do that since I do not have any more left for a radiator.
I am getting depressed. HAHAHA!!! Maybe more Jeep therapy tomorrow will straighten me out?
What do you guys think about my symptoms? Anyone? Anyone? Bueller?