Heater ?'s

[Logan Savage]

I have two questions concerning the heater in my 2002 3.7 Liberty . First a rundown of what the situation is & what I know . Both heater hoses get hot , about equally so . I flushed & back-flushed the heater core with garden hose pressure & just water . Water seems to flow freely both directions .
I have two Liberty's , this 02 & an 05 , the 05 has good heat . After flushing the 02 & still not getting but very little heat I suspected blend door problems since both heater hoses get hot . The blend door that controls which vents the air comes out works perfectly .
Using a 1 & 1/2 " hole saw I made holes in both Liberty's heater cases to view the heat controlling blend doors . I found that the blend door in the 05 moved farther in each direction than the one in the 02 .
I then removed the actuator for the blend door & installed a manually controlled cable to move the blend door . By viewing the blend door through the hole I made , I can tell the blend door is moving stop to stop using the cable control . I still have very little heat so I'm assuming the problem has to be in the heater core itself .
After flushing the core & finding water flowing freely both ways & both heater hoses getting hot I have come to the conclusion that coolant can flow through the core & bypass the little tubes in it . I sure wish I had an old core to cut open & verify this conclusion . Surely someone has done this or has an old core laying around they could cut open to test this theory .
I'm wide open to any suggestions or ideas that the conclusion I have come to is wrong before I buy a new core & tear everything apart to install it .
The heat gauge in the dash runs about halfway between cold & hot when the engine is warmed up .
All that being said , does anyone know for a fact whether the coolant can bypass in the core & 2nd , does anyone think that the problem could possibly be water-pump or thermostat related or even an air pocket ?

 

[HoosierJeeper]

TJKJ has said a few times that the KJ heater core isn't flushable. I'm doubting you have a t stat issue if it's getting up to temp in a timely manner and doubt it's the water pump if it's not leaking or squealing or overheating.

 

[Aceofspades]

I would be interested in seeing this too

 

[Logan Savage]

Just found this , probably answers my question .

Jeep Mechanic: Tim Mohr
Hi, my name is XXXXX XXXXX is a common problem with this year of jeep, they dont use a serpentine design on the heater core, it is like a radiator, with cross tubes going across the heater core, ovetime they get a calcium build up and it settles in the bottom of the core, since this is not a serpentine design, the coolant bypasses on the top of the core, so it will flow fine, but only half the heater core will get warm, on this design, it is impossible for you to flush the core, it just bypasses over the top of the core and wont flush the lower, you will need to replace the heater core, this also explains why the hoses are both hot, on the old design cores that were serpentine, if the core plugs, one hose would be hot and one would be just warm, but not on these,Tim

 

[tjkj2002]

Just found this , probably answers my question .

Jeep Mechanic: Tim Mohr
Hi, my name is XXXXX XXXXX is a common problem with this year of jeep, they dont use a serpentine design on the heater core, it is like a radiator, with cross tubes going across the heater core, ovetime they get a calcium build up and it settles in the bottom of the core, since this is not a serpentine design, the coolant bypasses on the top of the core, so it will flow fine, but only half the heater core will get warm, on this design, it is impossible for you to flush the core, it just bypasses over the top of the core and wont flush the lower, you will need to replace the heater core, this also explains why the hoses are both hot, on the old design cores that were serpentine, if the core plugs, one hose would be hot and one would be just warm, but not on these,Tim

Finally another that understands.