coolant tank

[XWrench3]

can someone please explain the coolant tank and how it works on a 2005 Liberty? i know how a conventional tank works, but this one with it's 2 sections and 2 hoses baffles me. and what happens if the engine actually overheats? i think it would just blow out of the tank right?

Thanks!

 

[Gyro]

D/L service manual here - http://www.colorado4wheel.com/manuals/Jeep/KJ/2005JeepKJServiceManual.pdf and go to section 7 under cooling.

Gyro

 

[XWrench3]

" NOTE: The coolant bottle has two chambers. Coolant will normally only be in the outboard (larger) of the two. The inboard chamber is only to recover coolant in the event of an overheat or after a recent service fill. The inboard chamber should normally be empty. If there is coolant in the overflow side of the coolant bottle (after several warm/cold cycles of the engine) and coolant level is above cold full when cold, disconnect the end of the overflow hose at the fill neck and lower it into a clean container. Allow coolant to drain into the container until emptied. Reconnect overflow hose to fill neck. "

This is the only thing I could find on the tank. so that's it? i still do not understand why it has a separate hose running from the radiator to the tank. or even how it gets from the tank back into the cooling system, since i have never seen anything in the second section of the bottle. in my mind, if it was supposed to work as described, there would have to be coolant in it at some point in time. unless there is a one way check valve someplace in either the radiator of coolant bottle.

 

[LibertyTC]

Part of the confusion could be from the FSM itself. Stating "typical" then shows a radiator with a cap for the KJ.
The engine cooling system will push any remaining air into the coolant bottle within about an hour of normal driving.
As a result, a drop in coolant level in the pressure bottle may occur.
If the engine cooling system overheats and pushes coolant into the overflow side of the coolant bottle, this coolant will be sucked back into the cooling system:
ONLY IF THE PRESSURE CAP IS LEFT ON THE BOTTLE.
Removing the pressure cap breaks the vacuum path between the two bottle sections and the coolant will not return to cooling system.
See also this thread: https://www.jeepkj.com/threads/coolant-pressure-relief.75621/

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[XWrench3]

The engine cooling system will push any remaining air into the coolant bottle within about an hour of normal driving.

so it will push the air into which side? the clear side, or the dirty side? are the 2 sides connected in any way? it appears to me that the dirty side is directly connected to the cooling system and coolant can flow into or out of the engine at any time. but i have not ever seen a drop of coolant in it ever.

really, I'm not trying to be difficult, I'm just trying to understand something that is not clearly explained in the S/M. i guess most people wouldn't give a grain of salt about it. but i like to know how things work. without buying a used coolant bottle and radiator to dissect in order to figure it out.

 

[uss2defiant]

here.
https://www.onallcylinders.com/2020/05/08/cooling-system-tech-overflow-tanks-vs-expansion-tanks/

the tank that we have is both combined into one.

The dirty side is the expansion side and the 'clean' side or driver side is the overflow side.

 

[JeepJeepster]

Speaking of which, I just had to replace the factory cap on my KJ. The rubber gasket had a bunch of little cracks around it and wasn't building pressure anymore. No clue how long it had been like this but Ive discovered you dont really need pressure on the system unless its running hot. My ZJ has had a bad cap for many years. When I tried to replaced it, the radiator started leaking so I put the old one back in it.

 

[uss2defiant]

if you get the loaner tool kit from your LAP you can also pressure test your rad. cap.

 

[JeepJeepster]

Ive not tried a kit from any other auto parts store but the one I rented from autozone DID NOT fit any of my jeeps.

 

[uss2defiant]

Ive not tried a kit from any other auto parts store but the one I rented from autozone DID NOT fit any of my jeeps.

for the KJ, you'll need both kits.
AutoZone cooling system test kit - 940427T & 647893T

One for the pump and the other kit for the fittings.

 

[JeepJeepster]

I ended up just buying the tester from harbor freight, works great and I think it was less than $100.

 

[tommudd]

so it will push the air into which side? the clear side, or the dirty side? are the 2 sides connected in any way? it appears to me that the dirty side is directly connected to the cooling system and coolant can flow into or out of the engine at any time. but i have not ever seen a drop of coolant in it ever.

.

Which side have you never seen any coolant in?

 

[XWrench3]

Which side have you never seen any coolant in?

the "clean" side.

 

[JeepJeepster]

Ive never seen anything in that side either and idk how coolant would get over there. It would need to be in the form of vapor and then condense back into a liquid. Otherwise coolant would need to get up into the radiator cap.

You have a good grasp on how it works. The only way for anything to get to the clean side is when the radiator cap is open (over 16psi) and its usually only air going over there. The clean side is open to the the atmosphere.

 

[XWrench3]

fvcetr

The clean side is open to the the atmosphere.

Now THAT I DIDN;T know! I think for an experiment, i am going to pour a pint of coolant into the "clean side" and let the engine get to normal operating temp, then shut it off just to see if anything happens thru 1 heat/cool cycle. if nothing happens, i will leave it that way for a week or so. i have always been curios almost to the point of dangerous. that line has gotten wider as i aged, which is proof positive that with age, comes wisdom.

 

[tommudd]

fvcetr


................................................................. which is proof positive that with age, comes wisdom.

Beg to differ , I know several that with age just comes more stupid time wasting thoughts
thinking of two friend's that fit that for sure
I do repairs for both of them on their trucks and the stupid things they worry about is funny at times, other times just a huge pain

 

[uss2defiant]

or if you're overheating

Ive never seen anything in that side either and idk how coolant would get over there. It would need to be in the form of vapor and then condense back into a liquid. Otherwise coolant would need to get up into the radiator cap.

You have a good grasp on how it works. The only way for anything to get to the clean side is when the radiator cap is open (over 16psi) and its usually only air going over there. The clean side is open to the the atmosphere.

 

[uss2defiant]

fvcetr


Now THAT I DIDN;T know! I think for an experiment, i am going to pour a pint of coolant into the "clean side" and let the engine get to normal operating temp, then shut it off just to see if anything happens thru 1 heat/cool cycle. if nothing happens, i will leave it that way for a week or so. i have always been curios almost to the point of dangerous. that line has gotten wider as i aged, which is proof positive that with age, comes wisdom.

what are you trying to do?

 

[XWrench3]

Beg to differ , I know several that with age just comes more stupid time wasting thoughts
thinking of two friend's that fit that for sure

i did NOT say ANYTHING about intelligence. dumb and smart is given to you at birth. but wisdom comes from a long line of experiences that you can draw from.

what are you trying to do?

what i am trying to do is determine exactly how and why the way that this works. there is not a problem (at least that I know of). i simply need to know how and why this works. at this point, for me, i do not know why the engineers went to the trouble of creating something that is not normally seen in cars (trucks, atv's, utv's, etc.).

 

[65Corvair]

I would think if you had an actual overheat condition (boiling the engine coolant) it would be collected in the “clean” chamber instead of being released to atmosphere. Then when your vehicle cools down, it is self added back to the cooling system.