Coolant system diagnostic assistance, please?

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yellocoyote

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Back when we got the first real cold snap here (single digits and under), I noticed a leak under the KJ. I got under to check it out, and it appeared to originate from the passenger side lower hose going into the radiator. The leak was a few drops overnight - not a huge amount by any means.

It leaked like this for about a week, and then stopped. Since then, I topped off the coolant reservoir because it was about 1/2" below normal when cold. I accidentally overfilled the reservoir :eek: because it's very difficult to actually see the level through the plastic. I considered siphoning it out, but was told that it wasn't necessary. (Not sure how accurate that is.)

Since all of that, the KJ hasn't leaked anymore. It doesn't have any temperature issues while I drive it... but once it's up to normal operating temperature, and I let it idle (like at a traffic light, parking lot, my driveway, etc.), I have coolant steam coming from under the hood. When I pop the hood, the coolant level is still on the high side from before, and it appears to be burning off from boil-over.

So the question is... if I siphon out the extra coolant, do you think this will stop? Aaron suggested maybe it has a bad reservoir cap... and I was wondering if maybe the thermostat is going bad (what are the indicators of bad thermostat?). Why else would the coolant be boiling itself out of the reservoir at idle vs when driving. Maybe the cold air temperature has a lot to do with it? The temperature indicator gauge in the dash never moves, so I can assume the vehicle is within an acceptable range.

I wonder what the explanation for all of this be if the weather were warmer - if it would behave the same way, or if I would have these same symptoms when the vehicle was in motion.

My KJ is pushing 164K miles, and I haven't had to replace the thermostat yet... or anything else cooling related except for the radiator in '09 and the normal coolant flushes.

Any ideas?
 

jnaut

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I'll second what journeyjim said. When my WP went, it would actually leak intermittently and an incredibly small amount. Like measurable in drops. There's a weep hole underneath the waterpump housing that will be slighly wet if you can reach under there. If it's weeping, then it's time to change the WP

As for siphoning out any excess coolant, shouldn't be a problem at all.
 

WesChapman

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Ditto on the water pump. Mine would leak a little bit, intermittently and then be fine for a while. Failed at about 42,000 miles. I think the replacement pump is starting to go as I'm seeing a similar leak again, this time at 103,000 miles.
 

yellocoyote

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There isn't any leaking from the water pump at all - I checked it then, and again today just to be sure.

When it did leak, it was from the lower hose going into the radiator (right side).
 

diyman

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My lower hose looks really bad, but still holds... Due for changing really soooon!

Maybe the clamp is getting old, get OEM replacement. I know, changing hose involves some WT#~@|@#F!!!
Sure, we all hope it's not a radiator issue ( [-o< )

If You can, try to re-use H-OAT, unless it's time has come too.
 

tjkj2002

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There isn't any leaking from the water pump at all - I checked it then, and again today just to be sure.

When it did leak, it was from the lower hose going into the radiator (right side).

Rather common issue on Jeep radiators in extreme cold temps.The side tank seals shrink so much that they leak a little in the very cold but once warmed up they do not leak,after a few cycles of this the side tank seal will just fail all together.

Same issue happened to my 2nd radiator(CSF brand),just a few drops here and there then one cold day all my coolant exited the lower passenger side tank in about 30 seconds.Watched it happen at work from inside the shop,glad I found a KJ radiator in town on a Sunday.
 

yellocoyote

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Rather common issue on Jeep radiators in extreme cold temps.The side tank seals shrink so much that they leak a little in the very cold but once warmed up they do not leak.

That sounds like that might be it then.

I've gone over the rest of the cooling system rather thoroughly as of late. Radiator looks good, water pump isn't leaking (and inside cabin temperature is still mighty hot :eek:), and the other hoses look to be intact/not leaking. Only other concern was thermostat. Once it gets warm enough this spring, I'm going to replace all of the cooling system hoses since it's never been done before. May also replace the water pump, just in case. Don't want to chance failure when out in Moab in May.
 

booslibby

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Hey man i had the same problem.WP went bad so i replaced everything! hoses thermostat and water pump and went ahead and put a new belt on since i had it off. The whole job for everything was prolly 1 1/2 hours very very simple job! 2 blots for fan shroud. 7 for pump and 2 for thermostat. i took pics if you want to see any.
 

booslibby

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But one thing i changed was that the 2002 liberty runs hot anyway. Th e electric fan kicks on at 218 which i din't like. They run them hot just for all the emissions crap. so with the new water pump i added a mopar mechanical fan. Not sure about yours but mine just had the electric fan.some guys say it takes up to 5 hP from the motor adding a mechanical fan but i really can't tell and it moves some serious air. I still get Hot air in the winter and can run for an hour or so and still open the coolant tank cap with my bare hand without any problem.Its just running Alot better. got pics if ya want to see them, hope this helps
 

tjkj2002

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But one thing i changed was that the 2002 liberty runs hot anyway. Th e electric fan kicks on at 218 which i din't like. They run them hot just for all the emissions crap. so with the new water pump i added a mopar mechanical fan. Not sure about yours but mine just had the electric fan.some guys say it takes up to 5 hP from the motor adding a mechanical fan but i really can't tell and it moves some serious air. I still get Hot air in the winter and can run for an hour or so and still open the coolant tank cap with my bare hand without any problem.Its just running Alot better. got pics if ya want to see them, hope this helps
Sorry to tell you the mechanical fan for the KJ does not lock up(actually pull's air) till about 230 degrees.The temp gauge in the KJ is a dummy gauge and will sit in the middle when the temp is between 180 some degrees to about 230 some degrees.
 

booslibby

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No man its moving some air! alot more just at idle than my Electric did when i had the AC on. maybe i had a bad electric fan, but right now just at a idle stuff will get sucked to the grill just from the air flow.Plus its not a liberty fan. i forget what we pulled it from. But to me it seems like the clutch kicks in at about 185 cause thats when it starts flexing. lol yeah. i dont use that jeep gauge,thats what started this crazy project. when the first electric fan died. the gauge still read on the cool side and it was over heating. so i dont know? anyway at 230 my temp light comes on and it has not been on since
 

Luke

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All I can ad is that my leak was supposedly due to overflow as well. The dealer siphoned coolant out of the reservoir to stop it. Good Luck
 

yellocoyote

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I added a hose clamp to the lower radiator hose today to see if that'll help with the leak issue until warmer weather arrives. Once that happens, then the system will be drained, I'll add a new water pump and new OEM hoses.
 

waywardtravel

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But one thing i changed was that the 2002 liberty runs hot anyway. Th e electric fan kicks on at 218 which i din't like. They run them hot just for all the emissions crap. so with the new water pump i added a mopar mechanical fan. Not sure about yours but mine just had the electric fan.some guys say it takes up to 5 hP from the motor adding a mechanical fan but i really can't tell and it moves some serious air. I still get Hot air in the winter and can run for an hour or so and still open the coolant tank cap with my bare hand without any problem.Its just running Alot better. got pics if ya want to see them, hope this helps

Did you actually change the operating temp of the engine by installing the fan? What about the spark plugs? If the plug is too hot it will create pre-ignition which is very dangerous if you like your engine.

O.K. the KJ has knock sensors and more likley it will eat your plugs fast causing runability issues then major carbon build-up.
 
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tjkj2002

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No man its moving some air! alot more just at idle than my Electric did when i had the AC on. maybe i had a bad electric fan, but right now just at a idle stuff will get sucked to the grill just from the air flow.Plus its not a liberty fan. i forget what we pulled it from. But to me it seems like the clutch kicks in at about 185 cause thats when it starts flexing. lol yeah. i dont use that jeep gauge,thats what started this crazy project. when the first electric fan died. the gauge still read on the cool side and it was over heating. so i dont know? anyway at 230 my temp light comes on and it has not been on since

Did you actually change the operating temp of the engine by installing the fan? What about the spark plugs? If the plug is too hot it will create pre-ignition which is very dangerous if you like your engine.

O.K. the KJ has knock sensors and more likley it will eat your plugs fast causing runability issues then major carbon build-up.
I doubt he changed the operating temps by much,maybe a few degrees at best.The OE t-stat does not start to open till 195 degrees and does not fully open until 218 degrees.Plus if the engine does not see a certian temp,more so in a set amount of time,it will turn on the check engine light.
 

moparman

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I also thought I had a lower radiator hose leak. But I think it was the radiator tricking me. Now leaking in 2 places. Next paycheck...
 
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