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Discussion Starter #1
Ok. This has been now nearly a two-week process. I was out driving my commander when I noticed the temperature gauge all of a sudden while at idle made some huge swings, real hot, then real cold, then slowly all over, while my engine lost some power and several warning lights came on. My first though and my first fix, thermostat. Bought a failsafe from Autozone. Mistake. Will get to that. So I pull the old thermostat out, it's missing several pieces of rubber on top. Seems like a problem. I put the failsafe in. I replace some coolant. Vehicle gets to operating temp, I attempt to bleed the system of air. It start overheating and I have to shut it off. Meanwhile, the upper radiator hose is making some crazy racket and I hear coolant snapping in the radiator. Probably more air. I spend the next WEEK slowly bleeding air out of the system. Just when I think I have it all (heater is blowing hot, everything seems fine) it overheats on me on the way to work, ETC light comes on, oil pressure light comes on, I'm thinking I blew a head gasket. After letting it cool and getting it home (took two stops to let it cool down again), letting it cool again, I pull the thermostat out to replace it with the Mopar OEM on I bought from the dealership. The failsafe was supposed to stick open when it got too hot. It wasn't open. It also fit just a bit too tightly when I originally put it in (shame on me). Mopar OEM thermostat fit like a glove. Get that installed, replaced coolant, burped the system, got hot air, doesn't overheat on the way to the repair shop, and all of the warning lights go away. He looks at it this morning and says he let it idle for 20-30 minutes with no overheating. I drive it off thinking, great, I fixed it. It begins to overheat as I pull into the parking lot at work. I call him back, he says air pockets. I'm thinking.... what were you doing with my jeep the last 6 hours if you weren't flushing the system? Resevoir is about to overflow, overfill on the radiator is full. So.... that is where I currently am, wondering how I will get home from work.

Anyone have any ideas? I'm completely stumped.
 

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I suppose it could be possible that it's beginning to fail, possible that if the bearings are lose and the impeller shifts slightly to one side or the other that it becomes extremely inefficient. Just a guess, because short of a defective thermostat, I have no idea.
 

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Discussion Starter #5
I suppose it could be possible that it's beginning to fail, possible that if the bearings are lose and the impeller shifts slightly to one side or the other that it becomes extremely inefficient. Just a guess, because short of a defective thermostat, I have no idea.
Yeah man. I'm stumped too. I find it highly unlikely that I have put in two defective thermostats. I heard the thermostat open/close when I was out with it earlier.

I have had zero signs of a blown head gasket. No white smoke, no water out the tail pipe, no milky oil, no oil in the coolant. The repair man I called later said it's possible it could be the head gasket and none of those things are happening because a cylinder is putting pressure into the coolant system. So I'll wait until morning when it's completely cold, pull the radiator cap off, put it back on, start and run it for like ten seconds and see if any pressure built up under the cap. If so, one of the cylinders is likely compressing air into the system.
 

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Discussion Starter #6
So. I found out that my radiator fan is hydraulic, and runs off the power steering fluid, which is actually a combo hydraulic/power steering fluid. That fluid is at below the "add" line. Is it possible that the hydraulic fan isn't kicking on early enough?
 

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I'm not sure. I have the 4.7 which only has the thermal and electric fans. Power steering fluid is cheap enough tho and topping it off certainly won't hurt anything.
 

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So. I found out that my radiator fan is hydraulic, and runs off the power steering fluid, which is actually a combo hydraulic/power steering fluid. That fluid is at below the "add" line. Is it possible that the hydraulic fan isn't kicking on early enough?
I'm kind of doubting it, but, top off your power steering fluid & see where you stand.
 

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Pop that bleed plug and let it run for a bit (20 mins) revving the engine a few times. It takes a little while. At least mine does.
 

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Thats pretty extravagant... ive replaced both the water pump and thermostat without those bleed issues. ? 5.7L
 

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Discussion Starter #13
Pop that bleed plug and let it run for a bit (20 mins) revving the engine a few times. It takes a little while. At least mine does.
Yeah, I can’t get the bleed plug open. Tried for days. WD40. Getting a longer handle for better leverage. Nothing.
 

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Discussion Starter #15
So I did have a drip leak at one of the heater hose tees that turned into a bigger leak. Replaced that today. No longer losing coolant. However, just bled/burped the system and it is still overheating. Got really hot air. And it is taking a while to overheat, but once it gets past the halfway marker on the temp gauge, it goes quick.
 

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So I did have a drip leak at one of the heater hose tees that turned into a bigger leak. Replaced that today. No longer losing coolant. However, just bled/burped the system and it is still overheating. Got really hot air. And it is taking a while to overheat, but once it gets past the halfway marker on the temp gauge, it goes quick.
FYI.....
 

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Thats pretty extravagant... ive replaced both the water pump and thermostat without those bleed issues. ? 5.7L
Same. Replaced upper radiator hose, thermostat, and water pump. Never had an issue until the heater core hose started leaking.
So I did have a drip leak at one of the heater hose tees that turned into a bigger leak. Replaced that today. No longer losing coolant. However, just bled/burped the system and it is still overheating. Got really hot air. And it is taking a while to overheat, but once it gets past the halfway marker on the temp gauge, it goes quick.
I'm going through this same issue right now, but I'm replacing the entire hose because I also need to get the passenger side valve cover off to replace the gaskets and the hose gets in the way. Seems to be a very common problem as there are several threads on here dedicated to that issue.
 

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Discussion Starter #19
Found out I put the incorrect, “universal” coolant in. A lot of places I have read said the commander might overheat because of this, though I'm not sure how much I believe that. But hey, science.

I am fairly certain I fixed the leak. I replaced the plastic heater hose tee connector right before the heater core that was giving me issues.

Haven't been able to afford to pick up the HOAT coolant or the special power steering/hydraulic fluid, but I am hoping these solve my problem.

My first test will be bblickle's suggestion about the block tester, because if it's a head gasket I'm going to have a lot more to worry about than the wrong coolant.
 
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