Overheating at low speeds and idle

tjventure

tjventure

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Joined
May 26, 2020
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7
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Vandalia, IL
02 TJ is overheating at an idle or cruising around town under 30mph. I have replaced the fan clutch with manufacturers fan clutch, replaced thermostat, filled radiator with coolant, checked coolant. None of these have fixed the problem. What is my next course of action? I was wondering about the water pump. But I'm not sure what I should try next. I have taken it to a local shop but they don't know Jeeps at all so it looks like I'm on my own. Appreciate any help you all can give me guys.
 
What do you mean by overheat? If the Jeep is really overheating with a new fan clutch you will hear a really loud roar from the fan, it should be extremely obvious. A bit of movement in the gauge is no problem and doesn't mean you are overheating. I might replace the radiator cap if you haven't. You might also consider the temperature sensor if there aren't other obvious signs the Jeep is actually getting too hot.
 
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Considering you’ve changed all that, I’d look at the water pump next. I’ve never had it happen myself, but I’ve seen pictures of removed pumps where the vanes on the pump had warn/corroded away. If that’s the case, it wouldn’t push as much water through the system as good vanes.
 
pagrey said:
What do you mean by overheat? If the Jeep is really overheating with a new fan clutch you will hear a really loud roar from the fan, it should be extremely obvious. A bit of movement in the gauge is no problem and doesn't mean you are overheating. I might replace the radiator cap if you haven't. You might also consider the temperature sensor if there aren't other obvious signs the Jeep is actually getting too hot.
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Good point, radiator cap would be and easy check.

Also, if your gauge is reading around 210*, that’s considered normal.
 
pagrey said:
What do you mean by overheat? If the Jeep is really overheating with a new fan clutch you will hear a really loud roar from the fan, it should be extremely obvious. A bit of movement in the gauge is no problem and doesn't mean you are overheating. I might replace the radiator cap if you haven't. You might also consider the temperature sensor if there aren't other obvious signs the Jeep is actually getting too hot.
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The gauge is clipping out in the red. All the way right. Check gauges light comes on as well. I haven't had the Jeep shut down or anything but if you get out and feel the hood it is extremely hot. Like instantly fry an egg hot, can't stand to touch it hot. I'm new in the last couple years to working on my Jeep myself so please don't take offense to any of my questions and excuse my ignorance......by change the radiator cap you mean just literally putting on a new cap? What with that would be causing an issue?
 
pagrey said:
What do you mean by overheat? If the Jeep is really overheating with a new fan clutch you will hear a really loud roar from the fan, it should be extremely obvious. A bit of movement in the gauge is no problem and doesn't mean you are overheating. I might replace the radiator cap if you haven't. You might also consider the temperature sensor if there aren't other obvious signs the Jeep is actually getting too hot.
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Also, what would be additional signs that I am actually overheating other than the gauges?
 
tjventure said:
Also, what would be additional signs that I am actually overheating other than the gauges?
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You described it pretty well, heat from the engine/hood, boiling coolant, strange smells and that sort of thing. Is it possible the new fan clutch isn't working as it should, does the fan have good resistance with the engine off if you try to spin it? The cap can cause overheating but probably not as bad as you describe. I would just replace it, they are $10.

I think that water pumps only need to be replaced when they leak due to a bad bearing or seal but opinions obviously vary. I think it is more likely your radiator is clogged or not working well. I might try to reverse flush it before spending money on more expensive parts.

I don't take offence, especially not to questions about Jeeps.
 
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I question whether it's actually overheating, or if it's just the temp gauge that showing it's overheating, which could be the result of a bad temperature sending unit.

I would suspect that, or a bad fan clutch.
 
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pagrey said:
You described it pretty well, heat from the engine/hood, boiling coolant, strange smells and that sort of thing. Is it possible the new fan clutch isn't working as it should, does the fan have good resistance with the engine off if you try to spin it? The cap can cause overheating but probably not as bad as you describe. I would just replace it, they are $10.

I think that water pumps only need to be replaced when they leak due to a bad bearing or seal but opinions obviously vary. I think it is more likely your radiator is clogged or not working well. I might try to reverse flush it before spending money on more expensive parts.

I don't take offence, especially not to questions about Jeeps.
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I did test the resistance on the fan and it does have good resistance with the engine up to temp and shut off. This is actually my second fan clutch. I bought one from O'Reilys first and changed it and then it started overheating again and I still had good resistance then so I took it to a shop and they told me that O'reily fan clutches are junk and I needed one from manufacturer so i had them order one and install it and I still have the same overheating problem so I really don't think I've got 3 bad fan clutches in a row.

How do I do the reverse flush? Is it difficult?
 
tjventure said:
I did test the resistance on the fan and it does have good resistance with the engine up to temp and shut off. This is actually my second fan clutch. I bought one from O'Reilys first and changed it and then it started overheating again and I still had good resistance then so I took it to a shop and they told me that O'reily fan clutches are junk and I needed one from manufacturer so i had them order one and install it and I still have the same overheating problem so I really don't think I've got 3 bad fan clutches in a row.

How do I do the reverse flush? Is it difficult?
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I do have water dripping out from somewhere but it looks really clear.......no color to it .I don't think it's coolant. It would be coolant leaking out if the water pump was bad right?
 
tjventure said:
I do have water dripping out from somewhere but it looks really clear.......no color to it .I don't think it's coolant. It would be coolant leaking out if the water pump was bad right?
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Probably condensate from running your A/C. Easy to check. Is the clear liquid leaking from the passenger side firewall?
 
tjventure said:
Not a bad idea. If I get close to the outside of the engine with the them gun is it going to read the same as the gauge should be reading the internal temp?
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Read the instructions that come with the tool. Many people mistakenly think the red laser aiming dot is what takes the temperature, they’re wrong. The beam pattern (you can’t see it) are normally 12:1. At 12 inches away the beam spreads out 1inch. In other words, you have to get the tool much closer to the part your trying to read the temperature of.
 
Fan clutch sounds good. A flush is Just like changing the coolant except you stick a garden hose into the thing and flush it out backwards when it's empty. There are probably good write ups floating around on how to do it the right way but that's all I've ever done.
 
Is there mud/other crap in between the ac condesor and rad?

Is the radiator shroud installed?

Are you running any grill inserts/angry eye/etc?
 
tjventure said:
02 TJ is overheating at an idle or cruising around town under 30mph. I have replaced the fan clutch with manufacturers fan clutch, replaced thermostat, filled radiator with coolant, checked coolant. None of these have fixed the problem. What is my next course of action? I was wondering about the water pump. But I'm not sure what I should try next. I have taken it to a local shop but they don't know Jeeps at all so it looks like I'm on my own. Appreciate any help you all can give me guys.
Click to expand...
Did you ever figure out what the problem is? We have the exact same problem and everything is new even the radiator
 
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