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Over heating issues.

4K views 37 replies 12 participants last post by  Jerry Bransford 
#1 ·
Hey all,

I've got a 2004 TJ, inline 6, with auto trans. I had to replace the radiator last summer, it had a pin hole leak, and everything was fine for a while. Starting having overheating issues on hot days with heavy traffic and lots of stopping and going. Also noted that sometimes when I stopped and shut it off to get gas, when I start it back up the temp would be in the red though it was within operating range when I shut it off.

I've had no problems with it during the fall/winter but now that the days are getting warmer I'm starting to have problems again.

A few things to note:

When I changed radiator out I refilled with Prestone premixed antifreeze.

I've noticed no visible leaks and I check often.

The resistance on my fan seems to be the same whether hot or cold.

Sometimes after I start it I have a thumping/popping sound that comes from the glove box area. It might happen right after starting or after I get down the road a quarter mile or so. Sometimes it's soft but once in a while it's really loud. Sounds like a vent flap or something. This sound is not a clicking sound but a single thump/pop.

Also; when I first got it the temp ran right at 210, now I'm running over 210. I'd say about 1/8th of the way to the red.

Any ideas?
 
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#4 ·
You said the resistance in the fan is the same whether hot or cold so does that mean when the engine is hot and off, it is difficult to spin? It should only be hard to spin when engine has been cold.

I think you need a special wrench or socket to remove it but it's simply bolt off and on. I didn't do mine but had mine done recently.
 
#7 · (Edited)
The fan clutch is supposed to be stiff to force the fan to spin when it's hot. It is only supposed to allow the fan to be easily spun by hand when the engine is cold and the fan isn't needed. So that your fan clutch is making the fan hard to turn by hand makes me think the overheating problem is elsewhere.

I'm kinda thinking perhaps the thermostat is hanging up/sticking closed. I'd replace it with a new Non-failsafe 195 thermostat like from Stant. Also make sure there's no trapped air in the cooling system, try burping it.
 
#34 ·
I agree. I'd forward and reverse flush the cooling system with the thermostat removed. Then replace the thermostat with an OEM thermostat and report back. I had a few problems with aftermarket thermostats, and prefer OEM, but that's just me! Good luck.
 
#9 ·
there's a flap in there (forget what it's called) that switches the air flow from vent to floor or to defroster, depends on where you have the dial set. Do you hear it only after you change the switch setting or just out of the blue it does it?
 
#10 ·
The flap you are probably referring to is called a blend door but it's function is mainly tied to the temp controls, not vent selection. Vent selection is controlled by 3 vacuum actuators located above the center hump.

OP, do as JBransford as suggested. Change the thermostat (195 degrees) and burp the system. Doubt it's the fan clutch but replacing it is extremely easy with a hand wrench.
 
#11 ·
Thanks for the advice. Going to switch out thermostat and see what happens.

As far as the thump from the glove box; I don't have to adjust the air for it to make the sound. I fact, it has done it when the air was off.

I wonder if it could have to do with the heater core and my cooling system needing to be burped?

Thanks again.
 
#26 · (Edited)
Update & New Question

When you buy your thermostat, look for the Superstat thermostat made by Stant. That particular model thermostat has a built-in ability to let trapped air escape out and eliminate the need to burp the system after installing it. Stant
I changed out the thermostat and flushed out the heater core too. I used the Stant Superstat 195 you suggested. After finishing up I started it up and let it get to operating temp. Instead of of running at the usual 220 the temp stayed just below 210. I ran the motor for about 30 mins with the heater on but the air never got hot. A also ran it for about 10 mins with the a/c on to see if it would make the temp go up but it still stayed under 210.

So I let it cool off then topped off the rad and started it up again. Let it run to operating temp with the heater set to full blast the whole time and still was not blowing hot air. Decided to take it for a drive; went 6 miles, the first 3 the temp stayed below 210, but on the drive home the heater started blowing hot air and then my temp started rising, almost hit 240 but then started coming down and leveled off at the the old running temp of about 220.

Figured I was still low and coolant so I let it cool down and checked it and sure enough the top of the radiator was dry.

Now my question is this, with my system being low on coolant why didn't it draw coolant from the overflow bottle?

By the way I began this adventure by running a chemical block test. Ran it three times with negative test results, but I'm not sure how dependable they are.
 
#16 ·
And you won't, everyone is brainwashed around here in thinking a motor that has been around since 1965 needs some special type of coolant. Regardless if it's the green, orange, pink ect ect all of them need to be replaced every couple of years.
 
#20 ·
Don't think the 98 came with HOAT Chrysler made that change in some newer year

Use what you want but change it periodically and be carful of incomparable mixtures

As far as old green not working with aluminum well aluminum intakes with cooling passages predate HOAT by decades
 
#24 ·
Don't think the 98 came with HOAT Chrysler made that change in some newer year
OP has an `04. I posted from the `04 FSM

Use what you want but change it periodically and be carful of incomparable mixtures

As far as old green not working with aluminum well aluminum intakes with cooling passages predate HOAT by decades
Decades ago the coolant didn't have a 5 Yr / 100,000 mile life.
I used to change my coolant every year decades ago. :)
 
#27 ·
The coolant from overflow bottle can only be sucked in to replace displaced volume sent out when hot but air in system that migrates to top is notify volume and thus no suction to pull volume out of overflow

Are you sure you are not loosing coolant somewhere including into exhaust or into oil
 
#31 ·
I've got no noticeable leaks. I've got a little water dripping out of the tail pipe but it is clear water with no visual traces of antifreeze. Can't smell any from the exhaust either. My oil looks good, clear with no chocolate milk look.

As I said, I ran a chemical block test three different times and it showed no trace of combustion gases, but then again I'm not sure about the accuracy of those tests. I did mine from the top of the radiator but I've seen some that do it through overflow tube. Any thoughts about this? Should I give it try and if so how do you do it?
 
#28 ·
The drawing of the coolant from the overflow to the radiator is not a mechanical process. Instead, as the radiator cools a vacuum is created that pulls the coolant back in. I bet if you let her cool for a few hours you would have seen your radiator top off.

You are showing classic symptoms of an air bubble. When you filled your radiator did you burp the system? You need to raise the front end high enough so that your radiator is the highest point of your engine then run to temp with the rad cap off. You'll know when your air pocket is gone because coolant will surge out. That's when you cap it and then top off once completely cool.

Also check for blockage in your overflow tank. Remove the overflow hose from the rad side and just blow into it. See if you can make it freely gurgle like chocolate milk.
 
#29 ·
Checked it this morn and the overflow bottle was still full while the rad needed some fluid. I added fluid and all it would take is about 1-2 cups. Surely that's not enough to make it overheat?

I didn't try to burp the system because I installed the Stant Supertat 195 which is suppose to eliminate the need to burp it.

Does anyone know if there is a Jeep Manual with a good troubleshooting guide. I've already got a Chilton's but it seems to be lacking in the troubleshooting area?

Thanks for any and all your input.
 
#32 ·
Yes. I made the mistake of not changing the cap when I changed out the radiator. Bought a new 18lb only to find it hissing and leaking fluid about a week later so I replaced it and got a new one. No problems with the cap since.

I can't thank you peeps enough for your help. I could put it in the shop but that would hurt financially. Plus I'd rather not pay someone for something I could do myself. Any suggestions are greatly appreciated.
 
#35 ·
Still having problems

So I finally found the time to flush out and burp my system and still had an overheat on a 90+ degree day after a couple hours of driving and was stopped with the a/c on with the Jeep in park. Turned the heat on and took off, temp went down, turned the a/c back on and everything was good.

Popped the hood when I got home and noticed that one of the a/c lines coming out of the firewall was frozen. Don't know if this is normal or what.

Today, 2 days later, I've had no other issues with overheating, but when I got home today I popped the hood just to have a look and noticed my overflow bottle was overfilled; not overflowing, the rad had just pushed hot coolant into it. I was hoping that as it cooled down it would suck the coolant back in, but it didn't. Have know idea what this means either. Also, I took off the radiator cap and the coolant was flush with the top of the radiator and didn't look low at all.

After all I've done already, I am perplexed, flustered, and butt-hurt.

Any advice is much appreciated, that is, anything besides taking it to a mechanic -I'm broke!
 
#36 ·
So I finally found the time to flush out and burp my system and still had an overheat on a 90+ degree day after a couple hours of driving and was stopped with the a/c on with the Jeep in park. Turned the heat on and took off, temp went down, turned the a/c back on and everything was good.
Since the overheating if occurring when stopped and not while driving (I believe that's what you're saying),
then I would put in a new fan clutch.
 
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