How can I troubleshoot overheating at idle?

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Medic203

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Jun 21, 2018
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Pittsburgh
2006 TJ, Last summer I completely redid the cooling system per the guide here (new hoses, radiator, water pump, fan clutch, T stat and housing), with no cheapo knockoffs. I'd had no issues, and hadn't noticed any leaks.

Today I'd driven home from work, and went back out to meet someone. While I was waiting in the lot, my check gauges light came on and my temp was up. So I popped the hood, let it cool for about 20 minutes and made it home. I didn't see any leaking or any residue on anything (my old water pump was leaking pretty bad). The only thing I noticed off hand was that the coolant overflow reservoir looked a bit low.

When I left I was waiting at a light and started seeing the temp gauge creep up a bit, but once i was driving it came back down to normal. I also popped the hook with it running and the fan is spinning.

Right now I'm waiting for it to cool down so I can check the level in the radiator.

So if the coolant level in the overflow tank is a good indication, i'm probably just down some fluid. How would I go about finding where i'm losing it though? There's really no obvious leaks (no puddle at home, no dripping, no dried coolant caked on anything I could see).
 
First and foremost, is it actually overheating? It's possible your gauge sending unit is bad.

However, if it is indeed overheating, please listen to what I am about to say and start with this. Check the radiator coolant level when the engine is cold. Take the radiator cap off and look. Is the coolant full to the top?
 
When the engine is warm, see if you have resistance when trying to spin the fan by hand.

When it's cold there should be no or very little resistance and when it's warm you should have a lot of resistance.
 
@Chris I can throw my OBD on and idle it, would that be the better way to check the actual temp? Not really sure how to do that.

@CodaMan I did have some resistance while spinning it right after I shut it off (when the CG light came on).

It's probably been shut down for about an hour now, with the hood up, in my driveway. I'm going to go check how warm it is.
 
@Chris
So it took about 1/3 of a gallon. I still had some Zerex 50/50 on hand. Looks like I found where it's been leaking. The tension clamp on the overflow tank basically disintegrated.

Didn't have any leaks when I filled up the radiator. Then went to top off the tank and then noticed the puddle, and it's leaking right where the hose meets the tank. Pulled that out and the clamp is done.

Can I just use a worm clamp there for now?
 
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Medic203 said:
@Chris
So it took about 1/3 of a gallon. I still had some Zerex 50/50 on hand. Looks like I found where it's been leaking. The tension clamp on the overflow tank basically disintegrated.

Didn't have any leaks when I filled up the radiator. Then went to top off the tank and then noticed the puddle, and it's leaking right where the hose meets the tank. Pulled that out and the clamp is done.

Can I just use a worm clamp there for now?
Click to expand...

A constant tension clamp is preferred, but a worm clamp will work too.
 
@Jerry Bransford I'll definitely keep an eye on it. I used the list in the post and bought everything from the links (so it should be the right cap). Looks like mainly the problem was that the tension clamp hit the end of it's life and looked more like C.

@Chris Thanks for the help, appreciate it!

Got a little worm clamp on there tightened it up and put what coolant I had left into there, and definitely wasn't leaking anymore.
Easy and cheap fix, thanks for help guys!
 
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Chris said:
Glad you got it all figured out, everyone loves a resolved thread 👍
Click to expand...
I feel like resolving your own thread should be a federal law :ROFLMAO: . I can't tell you how many threads I've read through where someone comes in, tells their life story, everyone is super helpful, and then they dip out.
 
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ItchyDong said:
I feel like resolving your own thread should be a federal law :ROFLMAO: . I can't tell you how many threads I've read through where someone comes in, tells their life story, everyone is super helpful, and then they dip out.
Click to expand...

I wish there were a way to enforce it!

No one likes digging up an old thread, hoping for an answer, only to see that the OP never returned to address the issue and whether it was solved or not.
 
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Chris said:
I wish there were a way to enforce it!

No one likes digging up an old thread, hoping for an answer, only to see that the OP never returned to address the issue and whether it was solved or not.
Click to expand...

The forum should buy 1 angry bird grill. Anyone who doesn't closeout their repair thread is required to install that grill for 1 month and take pictures of their TJ with it installed and sitting on a flex stand in a mall parking lot. Then post all those pictures in a newly created Shame thread.
 
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CodaMan said:
The forum should buy 1 angry bird grill. Anyone who doesn't closeout their repair thread is required to install that grill for 1 month and take pictures of their TJ with it installed and sitting on a flex stand in a mall parking lot. Then post all those pictures in a newly created Shame thread.
Click to expand...

That would be an awesome contest last place "prize". Whatever the contest was, the last place guy had to rock a sparkly pink angry bird grill until next year :ROFLMAO:
 
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