Coolant overflow without overheating

piroco66

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I need help with a coolant overflow to the overflow chamber in the reservoir without the vehicle overheating. The hoses are new, I replaced the cap, the water pump is new and the thermostat looks new (its about a year and a half old). First I thought the thermostat was reversed yet I checked and its ok yet after 5 minutes with the engine running the overflow chamber slowly starts to accumulate coolant. I have no idea what can be causing this issue. Has anyone had this issue and how to solve it please? Remember, there is no overheating; the temperature gauge stays slightly under the middle.
 

LibertyTC

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Welcome to the forums.
Did you use Mopar HOAT coolant or Zerex G-05 only?
Only use a Mopar thermostat.
Do you have the Mopar oem thermostat installed?
Is the coolant tank cap 16psi ?
What year is your Jeep?
 

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piroco66

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Thanks for your reply. The thermostat is aftermarket and the coolant is Peak North American vehicles 2002-2007. The Jeep is 2004.
 

LibertyTC

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You are using the wrong coolant. Water pump can get damaged & mixing coolants can cause gel like gunk/coagulation.
You will need to flush out the whole system and use the correct Mopar HOAT or Zerex G-05 coolant.
The best way to flush is using the pressurized dealer re-circulating machine. Out with the bad in with the HOAT.
Always refer to owners manual for fluid specifications. Mopar Thermostat & part number /photo is in post #2.
 
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piroco66

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And the type of fluid causes the coolant to seap into the overflow chamber? Has this happen tu someone else you know? Did the problem solve for them? Because I would do this tomorrow if It will work. Thanks again so much Liberty TC.
 

LibertyTC

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The reservoir tank should be filled to the cold line.
You could try removing air from the hex air bleed..
You must be registered for see images attach

Unless you have the correct thermostat installed, I can not stipulate course of actions, if it continues to overflow.
The tank may need replacement, doing a pressure test will confirm if the reservoir is able to hold pressure.
I would recommend that you familiarize yourself in regards to the cooling system.
The 2003 Factory Manual may help you. http://www.colorado4wheel.com/manuals/Jeep/KJ/2003JeepKJServiceManual.pdf
 

tommudd

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And the type of fluid causes the coolant to seap into the overflow chamber? Has this happen tu someone else you know? Did the problem solve for them? Because I would do this tomorrow if It will work. Thanks again so much Liberty TC.
To further what LibertyTC posted , if the coolant did damage the water pump, there could and would cause issues through out the whole system
Next how do you know it is not overheating ?
well known that the temp gauge is not reliabe or a good way of showing the temp, so ......
 

DadOSix

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Since no one else has gone there ...

do a test on the coolant reservoir and check for head gasket leaks.

combustion gas coming into the cooling system can cause issues here.
 

piroco66

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Just as a reminder, the coolant is no boiling/overheating.
The reservoir tank should be filled to the cold line.
You could try removing air from the hex air bleed..
You must be registered for see images attach

Unless you have the correct thermostat installed, I can not stipulate course of actions, if it continues to overflow.
The tank may need replacement, doing a pressure test will confirm if the reservoir is able to hold pressure.
I would recommend that you familiarize yourself in regards to the cooling system.
The 2003 Factory Manual may help you. http://www.colorado4wheel.com/manuals/Jeep/KJ/2003JeepKJServiceManual.pdf
I have a Haynes manual, would that one help? I actually did not know the reservoir could go bad, thanks for letting me know. I will buy a pressure tester and I did purge the air bubbles from the system. I am going to buy the OEM Mopar thermostat, my previous question related to that was pure curiosity because I really do want to know. I love learning the why of things. Again, thank you so much for your good advice. As soon as I test the pressure with the old thermostat and then with the OEM I will let you know the results.
 

uss2defiant

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pressure test your system with a loaner tool from your LAPS.
This sounds like what I've experienced in the past.
I had a crack in my reservoir tank. This caused my coolant to all flow into the overflow during the cool down period.
 

piroco66

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Wow, who would have thought. My reservoir may well have been damaged with a previous overheating. I got the heads worked on and checked the bocks surface. I replaced the radiator and water pump and I added the OEM mechanical fan. Tomorrow morning I will follow your advice. I have a local MOPAR parts and service centers close by (7 min drive). Thanks.
 

uss2defiant

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The crack on my reservoir tank was of course facing the firewall and actually took me some time to locate it.
I guess lesson learned here is to just unbolt the tank and remove it off the studs so you can absolutely check the entire tank.
but YMMV.

Good luck
 

piroco66

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I did remove it and can’t readily see a crack or perforation. this reservoir is 2 years old. The tank has a breather hole to the back against the firewall. Another interesting thing is that while the cap is off the coolant doesn’t seap into the overflow chamber and as soon as I place the 16psi cap on the coolant starts crawling into the overflow chamber. In the next couple of hours I will buy what you advised and rent the tool. Thanks.
 

piroco66

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You are using the wrong coolant. Water pump can get damaged & mixing coolants can cause gel like gunk/coagulation.
You will need to flush out the whole system and use the correct Mopar HOAT or Zerex G-05 coolant.
The best way to flush is using the pressurized dealer re-circulating machine. Out with the bad in with the HOAT.
Always refer to owners manual for fluid specifications. Mopar Thermostat & part number /photo is in post #2.
What does HOAT mean?
 

piroco66

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To further what LibertyTC posted , if the coolant did damage the water pump, there could and would cause issues through out the whole system
Next how do you know it is not overheating ?
well known that the temp gauge is not reliabe or a good way of showing the temp, so ......
Hello. I believe it’s not overheating because coolant is not bubbling at all. Not sure if it may overheat without bubbling.
 

piroco66

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Hello. I believe it’s not overheating because coolant is not bubbling at all. Not sure if it may overheat without bubbling.
Water pump is new, radiator is new, heads were repaired, new gasket sets, new timing chain front cover seals, no mixing of coolant and oil (no gel like or creamy gunk)
 

tommudd

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What does HOAT mean?
Hybrid organic acid technology (HOAT)
HOAT is the coolant that these KJs use, non of that green stuff, universal stuff only HOAT
Coolants of different technologies are not compatible nor interchangeable (OAT, HOAT or IAT). Mixing these coolants could result in: accelerated corrosion within the engine and cooling systems.
 

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