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Discussion Starter · #1 ·
I have a 2004 Jeep Wrangler that is new to me and it has started getting hot after very little driving. I filled engine coolant and tried again. Still got hot after just a couple miles. Coolant is still full. I need some ideas of what else to check.
 

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Fan clutch, thermostat stuck closed, poor radiator, poor waterpump.

What did you fill it with? Mixing coolants can create a nasty sludge that isnt good for anything.
 

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Discussion Starter · #3 ·
Prestone 50/50 diluted antifreeze/coolant. It says it's ok to mix with any color but my Jeep had green in it and this is green. It got hot before that though. I only filled it because it was a bit low and I was hoping that was the problem since it hadn't happened before.
 

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If it only gets hot while you're idling or in stop & go traffic but it runs cool at highway speeds, I'd bet on the thermostatic fan clutch having gone bad. The fan should be stiff & hard to turn when the engine is hot. Check the fan's resistance to being spun with your hand when hot, with the engine off of course.

If the temp gauge gets hot while at speed on the highway too, it's probably a stuck/bad thermostat. Replace it with a new 195 degree (no 165 or 180 degree thermostats!) conventional thermostat. A Stant SuperStat like at https://www.amazon.com/Stant-45359-...498688953&sr=8-1&keywords=stant+195+superstat would be a great choice. Go with a standard paper gasket, no RTV. Don't make the mistake of over-tightening the bolts that hold the thermostat housing to the head, that can strip the threads in the head and just ruin your entire day.

Don't go with a "fail-safe" thermostat. That type sounds good but they're not, they fail in the open position too easily and too often.
 

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Define "hot". What symptoms are the Jeep exhibiting that make you believe it is overheating? Are you reading the temp gauge and interpreting that number in your head as "too hot"? Or does the gauge actually go into the red/max out? Are you just putting your hand on the hood and feeling heat that seems too hot to you? Is there steam coming out of the radiator after driving for a while?
 

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Discussion Starter · #6 ·
The gauge actually goes to red and maxes out. When I lift the hood it is steaming. I killed it as soon as the gauge went red. Let it cool off before starting again to get it home. Had to repeat that process several times to get it home, hopefully, without harm.
 

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The gauge actually goes to red and maxes out. When I lift the hood it is steaming. I killed it as soon as the gauge went red. Let it cool off before starting again to get it home. Had to repeat that process several times to get it home, hopefully, without harm.
I still believe your thermostat is sticking, just replace it with a new 195 degree thermostat. Auto parts stores are open today, and as said above avoid "fail-safe" thermostats. If you go to a better quality store like NAPA, perhaps you can find a Stant which is a good quality thermostat. And if you can find a Stant SuperStat, better yet. There's no chance a low-end auto parts store like Autozone would carry anything that good.
 

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Discussion Starter · #9 ·
Yes, fan shroud looks to be in good shape as well as fan itself. I put paper underneath to test for leaks and there's a small coolant leak just left of center when facing the front of the jeep. Could it be the water pump?
 

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Yes, fan shroud looks to be in good shape as well as fan itself. I put paper underneath to test for leaks and there's a small coolant leak just left of center when facing the front of the jeep. Could it be the water pump?
Most likely, yes.
 

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A small coolant leak won't cause it to overheat though, unless you don't have enough fluid. I agree with Jerry, it's likely that your thermostat is stuck in the closed position. You should find out where exactly that leak is coming from though, and take care of it. If it's the water pump and you have to remove it to replace the gasket, I'd go ahead and replace it as well, unless you know how old it is.
 
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