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Discussion Starter #1
2007, Limited, 5.7 hemi, 199000 miles.

I was driving last night in 30° weather when I looked down to see my temperature gauge sky high. At the same time I noticed that I did not have any hot air blowing from my vents. After I babyed her to a parts store, I checked the fluid in the reservoir. It is slap full, and there are no obvious leaks.

So I just assumed thermostat... After replacing the thermostat had the same problem before I left the parking lot. then all of the sudden I heard a loud clicking/knocking/waterflowing noise coming from the heater core area. Then suddenly I had hot air and the engine temperature dropped dramatically to a normal temperature.

I drive it for 30 miles and it acted normal, then all of the sudden it started overheating again and I can't get the problem to go away now.

After letting it get to a normal temperature there were cold hoses to the heater core, to the back unit, upper and lower radiator hoses were all cold. That leaves me to believe that the water pump is not pushing water anywhere in the system. After I cut it off and it got quiet I noticed a "hot sizzling" sound coming from the water pump area. Keep in mind there are no leaks.

Sorry if there was already a thread, I've sifted through quite a few this morning!
 

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2008 Jeep Commander Sport 4.7L V8
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Is it an oem water pump or aftermarket water pump ? At 199k miles I would swap it if you feel that's it. Also the only accurate reservoire measurement is done once it's not at operating temp and cooled down. There's got to be a leak somewhere, it sounds like there's not enough fluid to circulate.

If you replace it as troubleshooting make sure to stick to oem or a good Napa one. I've replaced 4 on my 4.7l, all because the carquest brand sucks. I bought a metal impeller (oem used metal impeller and not plastic like carquest) Napa brand and it's done great.

Anytime I went through what you're going through it's either plugged or leaking. What color is the coolant in the radiator?
 

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Discussion Starter #3
Is it an oem water pump or aftermarket water pump ? At 199k miles I would swap it if you feel that's it. Also the only accurate reservoire measurement is done once it's not at operating temp and cooled down. There's got to be a leak somewhere, it sounds like there's not enough fluid to circulate.

If you replace it as troubleshooting make sure to stick to oem or a good Napa one. I've replaced 4 on my 4.7l, all because the carquest brand sucks. I bought a metal impeller (oem used metal impeller and not plastic like carquest) Napa brand and it's done great.

Anytime I went through what you're going through it's either plugged or leaking. What color is the coolant in the radiator?
By no means am I a mechanic. I just think it could be the water pump because every coolant hose is cold. It seems to me like there would be hot coolant at another hose if that pump was turning.
 

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2008 Jeep Commander Sport 4.7L V8
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Start with checking the color and condition of the coolant in the radiator.
As for the pump, it could be the impeller wore out. But I would search for a cause which checking the color and condition could help with, it could be a plugged radiator.
 

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2008 Jeep Commander Sport 4.7L V8
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Your signs do point to a clogged/bad radiator. If that is the case I'd suggest a good system flush (not chemically but a shop can vacuum out and through water etc.) And a radiator replacement.

Let's see what color the fluid is and viscosity first.
 

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Discussion Starter #6
Your signs do point to a clogged/bad radiator. If that is the case I'd suggest a good system flush (not chemically but a shop can vacuum out and through water etc.) And a radiator replacement.

Let's see what color the fluid is and viscosity first.
I blew the radiator out from both ends with water and air. Everything is clean and flowing properly. After inspecting the lower radiator hose, the internal coil that keeps it rigid has failed. It is rusted out into several pieces and I'm afraid it has traveled to the water pump. I even grabbed a piece out of the water pump housing with a finger. I'm wondering if that bottom hose is collapsing and cutting off circulation? I'm about to go grab another hose clamp and hook it back up to see if that is the cause. If that hose does not collapse I'm looking again at the water pump.
 

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I had the same thing with my 2008 Commander. Turns out I had a weak lower radiator hose that collapsed when the pump drew water. I replaced both the thermostat and lower radiator hose and haven't had a problem since.
 

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The hose is cheap, get the hose and a clamp and do a good flush of the system. You likely have a blockage/pieces somewhere even if that's the cause. I would most definitely proceed with a whole coolant system clean out to flush any contaminates out?

I'd replace the water pump since its off, at minimum put a new gasket on it.

Are you referring to the coil within the hose itself?
 

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Discussion Starter #9
So from what I can tell, it was a lower hose on the radiator collapsing. However I have learned that I'm losing water somewhere. Which I still believe is causing a slight temperature issue, not enough to make it overheat.

Once I get all of this straightened out and running at a normal temperature I will make another post...
 

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2007, Limited, 5.7 hemi, 199000 miles.

I was driving last night in 30° weather when I looked down to see my temperature gauge sky high. At the same time I noticed that I did not have any hot air blowing from my vents. After I babyed her to a parts store, I checked the fluid in the reservoir. It is slap full, and there are no obvious leaks.

So I just assumed thermostat... After replacing the thermostat had the same problem before I left the parking lot. then all of the sudden I heard a loud clicking/knocking/waterflowing noise coming from the heater core area. Then suddenly I had hot air and the engine temperature dropped dramatically to a normal temperature.

I drive it for 30 miles and it acted normal, then all of the sudden it started overheating again and I can't get the problem to go away now.

After letting it get to a normal temperature there were cold hoses to the heater core, to the back unit, upper and lower radiator hoses were all cold. That leaves me to believe that the water pump is not pushing water anywhere in the system. After I cut it off and it got quiet I noticed a "hot sizzling" sound coming from the water pump area. Keep in mind there are no leaks.

Sorry if there was already a thread, I've sifted through quite a few this morning!
Try to purchase a thermostat
 

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2007, Limited, 5.7 hemi, 199000 miles.

I was driving last night in 30° weather when I looked down to see my temperature gauge sky high. At the same time I noticed that I did not have any hot air blowing from my vents. After I babyed her to a parts store, I checked the fluid in the reservoir. It is slap full, and there are no obvious leaks.

So I just assumed thermostat... After replacing the thermostat had the same problem before I left the parking lot. then all of the sudden I heard a loud clicking/knocking/waterflowing noise coming from the heater core area. Then suddenly I had hot air and the engine temperature dropped dramatically to a normal temperature.

I drive it for 30 miles and it acted normal, then all of the sudden it started overheating again and I can't get the problem to go away now.

After letting it get to a normal temperature there were cold hoses to the heater core, to the back unit, upper and lower radiator hoses were all cold. That leaves me to believe that the water pump is not pushing water anywhere in the system. After I cut it off and it got quiet I noticed a "hot sizzling" sound coming from the water pump area. Keep in mind there are no leaks.

Sorry if there was already a thread, I've sifted through quite a few this morning!
Have you checked your fan. I’ve had two go bad and cause the overheating.
 

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Sounds like you have a lot of good suggestions. If you haven’t overhauled your cooling system it might be time. If you have to drain it to replace a hose which sounds like your issue, I would change all the hoses, sheaves and thermostat and seriously think about changing the pump too. The pump is a descent sized job so plan on a day to do it all. Take special care when bleeding the system, you might have to do it more than once. I’ve owned my Commander since it was new and I did my coolant system overhaul at about 150,000 miles. She has 230,000 on her now.
Btw it has to be a flow issue between the pump, radiator and engine. If it was a problem with a plugged heater core the engine wouldn’t overheat. If could also be air locked but I wouldn’t suspect that unless you worked on the system previous or a cracked hose.

Good luck.
 

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2006 Limited 5.7 HEMI Quadra-Drive II
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I agree with the overhaul of hoses, thermostat, water pump, check the radiator cap too. Is sheave a typo or a part? Never heard of that one. Make sure it's a 50/50 mix of distilled water and g05 coolant. Shouldn't be too bad, worse part is that blasted fan for me. Make sure to have the proper fan tool and a really large crescent wrench (I'm not sure what size wrench it actually takes). If you have the ability give the whole system a clean out and check the radiator for gunk.
 

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Discussion Starter #15
So far I replaced the radiator cap, the lower radiator hose, the water pump, and temperature sensor. Now I believe it is the heater core. I hear a lot of water movement, and there can't be too much else. I'm going to replace it this weekend and I will give another update.
 

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If you replaced the hose and water pump, did you purge the system?
 

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Discussion Starter #17
Okay, I replaced upper and lower radiator hose, water pump, radiator cap, temperature sensor. The radiator is a few months old.

All is working well, I do believe the water pump did it. I couldn't find anything wrong with the old pump, but it was old and it wasn't costly to replace it.

I'm going to go ahead and put a new heater core in at some point. I don't think the heater core is the issue, the water sloshing around has stopped. I have continual heat while running the vehicle👍👍

I've also modified the cooling system...
there's a lot of engine underneath that hood, and every time the hydraulic fan kicked in it would bog the motor down. So I bypassed the fan and straight lined it. After a new custom hose I have eliminated the hydraulic fan out of my jeep. Now it is throwing an open circuit code for the cooling fan, I'm not too worried about this. The new fan I replaced it with pulls more air than the hydraulic fan. I just wired it straight to the battery with a fuse, and am running it off of a toggle switch.
 

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Discussion Starter #18
Have you checked your fan. I’ve had two go bad and cause the overheating.
I would suggest ripping the hydraulic fat out and going with electric. I bought a fan that I believe pulls around 4,000 cubic feet per minute. The fan came from O'Reilly's, the shroud came from walmart. I built the fan shroud out of a box fan frame and it works like a champ.
 
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