Temperature gauge running warm

Chasitek

TJ Enthusiast
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Joined
Feb 19, 2018
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655
Location
Chapel Hill, NC, USA
So when it hit 90 degrees outside the other day and right before I was going to go camping, my jeep overheated in the chick fil a drive thru. I thought it was low coolant because I know I have a bad heater core since it’s been slowly leaking through the a/c drain vent tube. There was no coolant in the overflow reservoir so I began to open the rad cap slowly and let the pressure out and when I thought all the pressure was out I opened it up fully and it spewed out like a water fountain. Then, of course the coolant was low so I had a friend pick me up to get some more coolant and I filled her up but my jeep overheated again. I pulled over and replaced the thermostat with a regular 195 but it overheated again. I replaced the waterpump and now my temp is reading just above 210 which I know some people say is fine but my worry is that it’s reading just above 210 on a cool day. What about when it’s hot again. Before ever overheating my jeep sat DEAD ON 210. Is it a bad temp sensor or maybe a bad thermostat?

93A768AB-B835-4898-A8B5-3AC0865F53EF.jpeg
 
I'm guessing this is AC On?

Maybe fan clutch. when I was having overheating issues at idle (but not highway speeds), i replaced water pump, t-stat, and fan clutch. no more overheat. I'm 95% sure it was the fan clutch causing it.
 
I'm guessing this is AC On?

Maybe fan clutch. when I was having overheating issues at idle (but not highway speeds), i replaced water pump, t-stat, and fan clutch. no more overheat. I'm 95% sure it was the fan clutch causing it.
So when it hit 90 degrees outside the other day and right before I was going to go camping, my jeep overheated in the chick fil a drive thru. I though low coolant because I know I have a bad heater core since it’s been slowly leaking through the a/c drain vent tube. There was no coolant in the overflow reservoir so I began to open the rad cap slowly and let the pressure out and when I thought all the pressure was out I opened it up fully and it spewed out like a water fountain. Then of course the coolant was low so I had a friend pick me up to get some more coolant and my jeep overheated again. I pulled over and replaced the thermostat with a regular 195 but it overheated again. I replaced the waterpump and now my temp is reading just above 210 which I know some people say is fine but my worry is that it’s reading just above 210 on a cool day. What about when it’s hot again? Before ever overheating my jeep sat DEAD ON 210. Is it a bad temp sensor?

View attachment 165007
It’s not overheating anymore, just running warm. Also fan clutch has good resistance when I spin it. A/C being on doesn’t make it increase. Temp stays the exact same.
How does your radiator look? When you replaced the coolant, did you burp the system?
Radiator was replaced less than a year ago by the previous owner who I knew. Not sure if it’s OEM though. I’ll have to ask. I read that newer tj’s are self burping. Also when I tried to burp it like I used to with my old 97 by topping it off as it went down I couldn’t. Coolant was flowing out with the rad cap off. It wasn’t at operating temp tho. I didn’t want all the coolant to flow out by the time it got to operating temp.
 
Tough to really troubleshoot a system with a known leak. I know it's sucks but you probably should replace the heater core. I'd replace the radiator cap too, after the core.
 
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Tough to really troubleshoot a system with a known leak. I know it's sucks but you probably should replace the heater core. I'd replace the radiator cap too, after the core.
The leak is VERY small. There’s no way it’s what’s causing the temp gauge to run warm. Also, it didn’t run warm before. There is 100% full coolant in the system right now. I’ll replace the rad cap. Rubber all looks good but it’s a cheap fix so i’ll see if that’s it. Also it DEFINITELY is holding a lot of pressure when hot.
 
I had a similar problem last year. Turns out I hadn't bled the system as well as I thought and there was a little air trapped. Once I bled it out, the problem went away. Had a new radiator, newer water pump, newer thermostat, and even replaced the radiator cap just in case. Fan clutch #2 works but leaks oil. Piece of crap.... electric fan is on my maybe list. Just not sure if it is worth the hassle in regard to reliability and benefits.
 
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I had a similar problem last year. Turns out I hadn't bled the system as well as I thought and there was a little air trapped. Once I bled it out, the problem went away. Had a new radiator, newer water pump, newer thermostat, and even replaced the radiator cap just in case. Fan clutch #2 works but leaks oil. Piece of crap.... electric fan is on my maybe list. Just not sure if it is worth the hassle in regard to reliability and benefits.
What year was your tj? I will definitely check into bleeding it more. How did you bleed yours? I read they’re self bleeding.
 
What year was your tj? I will definitely check into bleeding it more. How did you bleed yours? I read they’re self bleeding.

2004. You just sit it on an incline (driveway) and start her up. Crank the heater up to circulate fluid and leave the radiator cap off. Keep filling it up. It's called 'burping' as the air will cycle through the system and exit at the uppermost part. IE the radiator cap when it's on the driveway. Once you think you've got all the air out, drive it around, (and on some sweet jumps as Neapolitan Dynamite would say) let it cool, and burp it again.
 
2004. You just sit it on an incline (driveway) and start her up. Crank the heater up to circulate fluid and leave the radiator cap off. Keep filling it up. It's called 'burping' as the air will cycle through the system and exit at the uppermost part. IE the radiator cap when it's on the driveway. Once you think you've got all the air out, drive it around, (and on some sweet jumps as Neapolitan Dynamite would say) let it cool, and burp it again.
Ah yeah. I did all that. I wasn’t sure if you did it a different way or something. I only did it once though so I’ll do it a few more times and see if it helps.
 
That’s what I had thought.
Mine doesn’t have a pinhole either so I think ours needs to be bled.
A couple of things come to mind. Maybe I didn't have the reservoir full enough. Maybe I didn't use the heater at all. (Not likely) Maybe I didn't drive it enough to let it do its thing. In any case, after many many miles of this I used the burping procedure and got air out of the system.
 
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I replaced my radiator last month and used this kit. Easy to use, no spill, no mess.


https://www.eastwood.com/eastwood-c...8UYyJuaQOUZkYxY3MCLl7jiWTjtEfF8saAv-LEALw_wcB

I used that kit too.. worked well. I wasn't able to do it with zero spills but definitely less than normal. If the thermostat you installed did not have a jiggler please consider drilling a 1/8" hole at 12 oclock to let it burp. I did that and had no issues with the system self bleeding the air out on my relatively flat garage floor.
 
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I pulled over and replaced the thermostat with a regular 195 but it overheated again. I replaced the waterpump and now my temp is reading just above 210 which I know some people say is fine but my worry is that it’s reading just above 210 on a cool day. What about when it’s hot again. Before ever overheating my jeep sat DEAD ON 210. Is it a bad temp sensor or maybe a bad thermostat

First off, it amazes me that you just pulled over and replaced a thermostat. That is a gear-head skill level of a jeep guy (like Jerry).
Now, granted you have that skill - you call over heating at 215 ? I had that on mine (over 210) for months and did not even sweat on it. It self burped itself over time and level off back to 210.

Overheating to me is if the needle is on the red zone.
 
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First off, it amazes me that you just pulled over and replaced a thermostat. That is a gear-head skill level of a jeep guy (like Jerry).
Now, granted you have that skill - you call over heating at 215 ? I had that on mine (over 210) for months and did not even sweat on it. It self burped itself over time and level off back to 210.

Overheating to me is if the needle is on the red zone.
You are correct. Overheating is when the car actually overheats (is in the red). My post says nothing about 215 being overheating. I’m not trying to be mean but please read my post before responding to it. My concern is that A, it always sat dead on 210 before it overheated so, why isn’t it now? And B it sat at 215-220 on a cool day, I think it’ll rise on another hot day like the day it overheated as in FULL red. I’m asking for people’s ideas on the problem seeing as it seems the waterpump fixed my overheating but it hasn’t fully gone back to normal.
I replaced my radiator last month and used this kit. Easy to use, no spill, no mess.


https://www.eastwood.com/eastwood-c...8UYyJuaQOUZkYxY3MCLl7jiWTjtEfF8saAv-LEALw_wcB
I used that kit too.. worked well. I wasn't able to do it with zero spills but definitely less than normal. If the thermostat you installed did not have a jiggler please consider drilling a 1/8" hole at 12 oclock to let it burp. I did that and had no issues with the system self bleeding the air out on my relatively flat garage floor.

I appreciate your link but I do not need to replace my radiator. It has already been replaced. Also, I don’t need a kit to replace a radiator. They have a petcock on them to drain them and a funnel is like $5 bucks at any auto part store. No need for a kit.

As far as drilling the little holt in the thermostat. I usually do but I didn’t have a drill or drill bit around at the time.
 
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