Coolant overflow without overheating

Jeremy-WI

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It might be the natural expansion of water as it is heated and that is the purpose of that tank. I helped people install outdoor woodburners years ago and the models that didn't have an expansion tank would have water pouring out on the top as the wood heated the water up. Water expands about 4% from room temp-boiling temp, some of the smaller wood burners held 100 gallon
 

piroco66

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Got it. I appreciate the link to the manual that was posted in this thread. I’m having my system flushed monday. I borrowed the pressure test tool from LAPS. Will test now and after the flush with the new thermostat. Can’t thank you guys enough, you are much appreciated.
 

uss2defiant

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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.

the hole in the overflow section of the tank is there to spill out when the overflow section if overflowed with coolant.

I wonder if there's an internal crack between the pressurized side (expansion tank) and the overflow side. Maybe you can use some water + red food coloring to see if it leaks into the overflow side when you do your pressurized test. Of course, this means bench testing it. :)

Keep in mind that our reservoir tank has an expansion side and an overflow side.
 

uss2defiant

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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.

if you are going to AutoZone, you'll need both cooling system test kit - 940427T & 647893T.
I believe the single loaner tool from O'reilys will still work as well.
 

piroco66

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I got the kit from Advanced Auto Parts and it is a big case with a slew of parts/adapters in it.
 

piroco66

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I just pressure tested the bottle an it does not hold pressure, coolant just starts Flowing into the overflow chamber. This test was done with The old thermostat. I am having my system flushed today instead of tomorrow and the OEM thermostat installed as well.
 

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RockinRam96

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So it sounds like you recently did some work with the coolant system, replacing major components.

FWIW, I have had many engines leak coolant out the over flow until they settle down and find their happy place. I can fill to the full line and when hot leak until again finding their happy place. If you have just done some major work to the coolant system and engine, maybe it is just seeking that happy level.

... just my $0.02.
 

piroco66

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Well, finally done with the cooling system work. OEM coolant (HOAT), OEM thermostat, OEM coolant reservoir and purged the bubbles out of the system. Test drove around the neighborhood for 20 minutes and no leaks were detected. Also the Temp gauge reached just below the middle. Then I drove to an A/C shop to have the A/C checked and the Oil pressure light started turning on at low revolutions…..and as soon as I accelerated slightly it turned of. At every stop light going home I place the trany in neutral, the revolutions increased and light turned off.
The oil pump is new so I am thinking…could it be the oil pressure switch (its a new switch, non-OEM). I am going to buy an OEM switch by tomorrow yet I need the opinion of smarter/more knowledgeable people than me. Thanks for your advice.
 

piroco66

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A couple of pics with part numbers
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coolant reservoir
 

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tommudd

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Well, finally done with the cooling system work. OEM coolant (HOAT), OEM thermostat, OEM coolant reservoir and purged the bubbles out of the system. Test drove around the neighborhood for 20 minutes and no leaks were detected. Also the Temp gauge reached just below the middle. Then I drove to an A/C shop to have the A/C checked and the Oil pressure light started turning on at low revolutions…..and as soon as I accelerated slightly it turned of. At every stop light going home I place the trany in neutral, the revolutions increased and light turned off.
The oil pump is new so I am thinking…could it be the oil pressure switch (its a new switch, non-OEM). I am going to buy an OEM switch by tomorrow yet I need the opinion of smarter/more knowledgeable people than me. Thanks for your advice.
Yes this is another one of the items that just requires an OEM switch
 

piroco66

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OK, it feel comforting to have this forum looking out for us Jeep greenhorns. Having not only member but also moderators pitching in to help a fellow Jeep owner keep his/her ride alive is very much appreciated. Will see whats next.

P.S. I will read the manual to see what the RPM’s are supposed to be at idle. Dont know if a turn of a ***** (in the throttle body accelerator) may be recommended or not. Thanks tommudd.
 

tommudd

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OK, it feel comforting to have this forum looking out for us Jeep greenhorns. Having not only member but also moderators pitching in to help a fellow Jeep owner keep his/her ride alive is very much appreciated. Will see whats next.

P.S. I will read the manual to see what the RPM’s are supposed to be at idle. Dont know if a turn of a ***** (in the throttle body accelerator) may be recommended or not. Thanks tommudd.
Most times at idle and warmed up about 650, or at least that is what I have seen in a few hundred of them
 

piroco66

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Hope that fixes the problem tomorrow. your experience is beneficial to all of us in the forum. Will comment on results tomorrow. Thanks!
 

uss2defiant

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CPS and CKS are some other sensors that need OEM as well. The tolerance on these sensors that are aftermarket is bad.
 

uss2defiant

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FYI Zerex G-05 is HOAT we need so you don't have to buy Mopar brand.
Same thing for ATF+4. you can get the cheapest.
 

piroco66

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Hey, thanks uss2defiant, thats good to know. Will keep that in mind.
 

piroco66

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I installed the OEM Oil pressure switch and I noticed a big difference between it and the aftermarket. I have not tested the vehicle yet. Will do so tomorrow. Hope it fixed the problem.
 

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