Coolant bubbling in overflow tank

R

Rocks58

New Member
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Jul 19, 2020
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Location
Parker, Colorado
I just bought a 2004 TJ and maybe jumped on it too soon (buyer did not beware this time).
After my ride home of about 15 miles the coolant was bubbling in the overflow tank after the motor was turned off. I replaced the thermostat and topped off coolant. Drove it a couple times around the neighborhood without any issues (no bubbling). Took my daughter out yesterday for about 45 minutes of parking lot manual transmission lessons and it started bubbling again toward the end of our time out and kept bubbling when I turned off the motor. The oil is clean, nothing in the coolant, no white smoke in the exhaust, temp gauge is just over 210, no codes and no leaks. My novice opinion in the worse case is that the head gasket is in the beginning stages of leaking. Any other suggestions are appreciated.

New member and I look forward to being a part of this group.
 
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Cap replaced and no boiling after getting it up to temp and driving around. Now noticed that coolant is dripping from the front of the motor. Guessing from the water pump. Doesn’t look like it’s coming from the thermostat housing. I’ll review the cooling system refurb thread and get to work.
 
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Following the Cooling System Overhaul thread instructions and parts list, I replaced the following:
Radiator,
Water pump,
Thermostat,
Fan clutch,
Belt tensioner,
Belt and
Radiator cap.
No leaks and no new issues. The job was very straightforward and not difficult. I’m getting similar results on temps as others that posted following their overhaul. Prior, temps were reading just above 210 and now it’s reading just under 210. Now on to the next upgrade....
 
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Glad you got it all sorted out, and most importantly, thanks for the update!

A refreshed Mopar cooling system should leave your TJ happy for a while to come now (y)
 
Rocks58 said:
Following the Cooling System Overhaul thread instructions and parts list, I replaced the following:
Radiator,
Water pump,
Thermostat,
Fan clutch,
Belt tensioner,
Belt and
Radiator cap.
No leaks and no new issues. The job was very straightforward and not difficult. I’m getting similar results on temps as others that posted following their overhaul. Prior, temps were reading just above 210 and now it’s reading just under 210. Now on to the next upgrade....
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Exact the same problem! Changed everything with cooling. Now, the TJ runs fine. Thank god NO head gasket or head cracked. Thanks guys for help with my thermostate question.
 
Great work, and I'm glad you got it sorted out. FWIW, I had the same experience and found that even when I was boiling coolant, the gauge never showed any significant change. I plugged my OBD reader in and connected to Torque on my phone and found the Jeep was actually reaching upwards of 230 degrees with the gauge moving just to the high side of 210. That factory gauge kinda stinks.
 
-T. said:
That factory gauge kinda stinks.
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No it doesn't. It tells you exactly what you need to know. If it is not in an overheat condition from a defective cooling system, it hovers around the 210 mark. If you have a problem, it goes over into the red and the check gauges light comes on. Everything else is pretty much useless.
 
Just saying, mine was boiling in the coolant bottle, so there was a defect in the cooling system (turned out to be a worn fan clutch) And when in it was in that state the needle was just showing just barely over 210. But maybe its just my rig. You have far more knowledge then I do about these things.
 
-T. said:
Just saying, mine was boiling in the coolant bottle, so there was a defect in the cooling system (turned out to be a worn fan clutch) And when in it was in that state the needle was just showing just barely over 210. But maybe its just my rig. You have far more knowledge then I do about these things.
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210 is just a reference point. The reason that we pressurize the system is to raise the boiling point of the coolant higher than the 212F that water boils at sea level. Also one of the reasons we run anti-freeze. You really don't need to know the coolant exact temp just like you don't need to know the temp of the flame front when the fuel air mixture explodes after the plug fires.
 
mrblaine said:
210 is just a reference point. The reason that we pressurize the system is to raise the boiling point of the coolant higher than the 212F that water boils at sea level. Also one of the reasons we run anti-freeze. You really don't need to know the coolant exact temp just like you don't need to know the temp of the flame front when the fuel air mixture explodes after the plug fires.
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Agreed on the the temp gauge. I've always thought of them as a relative indicator and not a precise temp measurement. It's either cold, just right or too hot with some minor fluctuations.
 
One more followup on my coolant system overhaul. On startup, prior to the overhaul and after, the exhaust spits out a bit of liquid. Is this a head gasket concern? No other symptoms and I haven't had a combustion gas check done on the cooling system yet.
 
mrblaine said:
210 is just a reference point. The reason that we pressurize the system is to raise the boiling point of the coolant higher than the 212F that water boils at sea level. Also one of the reasons we run anti-freeze. You really don't need to know the coolant exact temp just like you don't need to know the temp of the flame front when the fuel air mixture explodes after the plug fires.
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I get that. However, wouldn't you agree that, once the Jeep is boiling over, the needle should be headed for the red? Mine was not. That's all I am saying. I'm not saying it necessarily should have been in the red. But there is a a lot of landscape on the little gauge between 210 and the red side of the gauge. Mine had not even moved close to the red. When warm and running 'normally' it is just on the low side of the 210 mark on the gauge. When it was blowing coolant down the side of the Jeep and onto my buddies windshield behind me, it had moved just to the other side of the 210 mark. When I put the OBD on it, it was running at 230 degrees, which theoretically should have had the gauge nudging into the red.
 
I would personally prefer if the gauge was a little more sensitive to overheating. Mine has run all the way up to 240 before without the gauge giving me any sign something is wrong. Other than that I don't care about the exact temp the Jeep is running at.
 
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