eater Core questions (yeah as always)

[JBDive]

So I had my radiator replaced last year and since then the heater core has clogged a few times. Clearly the guy doing the radiator did not flush the system fully or correctly. No problem, pull the hoses, backflush and we have heat.

This year however I again had very little heat the other day, flushed it, felt like good heat but that was with outside temps of 50. Driving over the weekend in temps around 34 it was barely comfortable in the Jeep so I of course assume it just clogged back up.

So I'm flushing again today and nothing came out. I captured all the rinse and there was simply nothing there. Flow appeared good. Should mention prior to that I used a laser temp gun on the hoses and they both came in around 180 if I remember correctly, at the very least there was a marginal difference between them.

So my question is how is the heater core designed? If the core is actually clogged will the water back flushing the system bypass the core and just run along the top like a radiator will? Is the design the same as a radiator or is the Liberty core a solid tube with fins? If I have a good flow going both directions is this proof the core is not clogged or could it be clogged and the water is just bypassing the general core?

 

[drowssap]

Ok...forgot what it is called at the moment but are you sure the flapper door is opening completely to allow the heat in? Also is there any debris blocking the flow of air across the eater core?


EDIT: Did you see what I did there? HAHAHA

 

[JBDive]

To further make me think the core is hollow across the top and this acts as a bypass I was using some clear tubing for the flush so I could see what was passing through. With both sides of the core attached to hosing which I ran up to the hood latch so they are clearly higher than the core I then attempted to refill the core with antifreeze through the tubing. I was not able to get even a cup into the core before it showed up coming out the other side.

 

[JBDive]

Ok...forgot what it is called at the moment but are you sure the flapper door is opening completely to allow the heat in? Also is there any debris blocking the flow of air across the eater core?


EDIT: Did you see what I did there? HAHAHA

Actually blocking the outside air door would increase the heat level if the blend door was faulty. I don't think it has anything to do with the blend door, the problem would be evident during summer as well with the A/C unable to cool the interior when not on recirculating.

 

[drowssap]

To further make me think the core is hollow across the top and this acts as a bypass I was using some clear tubing for the flush so I could see what was passing through. With both sides of the core attached to hosing which I ran up to the hood latch so they are clearly higher than the core I then attempted to refill the core with antifreeze through the tubing. I was not able to get even a cup into the core before it showed up coming out the other side.

Or as you stated it could be filled with debris that was never removed entirely from the first flush and it is just consuming most of the interior's volume.

 

[drowssap]

Actually blocking the outside air door would increase the heat level if the blend door was faulty. I don't think it has anything to do with the blend door, the problem would be evident during summer as well with the A/C unable to cool the interior when not on recirculating.

Wouldn't the blend door stuck in favor of the ac prevent heat from coming through the system? The heater core and ac evap are two separate pieces of hardware. If the INTERIOR blend door favors the AC...it will limit the flow of heat but I could also be completely wrong about what you should be looking at and you should just be switching out the heater core!

 

[JBDive]

Followup.

Put everything back together, refilled as needed, parked on incline with car at full temp to make sure to bleed out any air.

Hose temps around 170 with just about 10 degrees difference between in and out with heater on, fan at full blast, outside temps around 55. Vent heat is right around 105-110 which is lower than I know it was before.

 

[JBDive]

Or as you stated it could be filled with debris that was never removed entirely from the first flush and it is just consuming most of the interior's volume.

Surely the unit holds far more than a cup of fluid. I was able to get maybe 3/4 cup in. Again air, water, flush passes without restriction which makes me think the unit is identical in design to a radiator which allowed for fluids to bypass the entire radiator when clogged.

Does anyone know if the design is actually one tube running through the entire core or is there an area across the top of the core which is open internally and fluids can pass in and out without ever going through the core proper?

 

[JBDive]

Wouldn't the blend door stuck in favor of the ac prevent heat from coming through the system? The heater core and ac evap are two separate pieces of hardware. If the INTERIOR blend door favors the AC...it will limit the flow of heat but I could also be completely wrong about what you should be looking at and you should just be switching out the heater core!

Well I pulled the glove box and you can clearly hear the doors closing.

I'll add that in an effort to get heat this past weekend I placed the unit on A/C, recirculating air, full heat and the temps were nearly identical to heat only so I'm pretty sure the door is fine.

 

[GunnerSchenck]

Are you running HOAT coolant and did the mechanic that replaced the radiator make sure to put HOAT in as well?
What do you mean parking it on an incline to bleed the air? I'd imagine to help circulate coolant through the heater core, but this isn't needed if you have the heater turned on high.
Just my 2 cents but sounds like your water pumps kickin it. Especially if you can hear the blend doors actuating.

As for the amount of fluid going into the heater core, I wouldn't imagine it would take much more than that amount of fluid. Heater core is not very big at all, and most of what you see is just the fins. It's basically 1 tube that goes in the inlet, turns into the cooling tubes and comes out the outlet.. simple U shaped tubes design, likely less than a foot long each..

 

[tjkj2002]

You must be registered for see images attach

What your heater core looks like(basic idea,Inlet/outlet tubes are slightly different).The coolant will flow just fine through it even when clogged.

 

[JBDive]

Are you running HOAT coolant and did the mechanic that replaced the radiator make sure to put HOAT in as well?
What do you mean parking it on an incline to bleed the air? I'd imagine to help circulate coolant through the heater core, but this isn't needed if you have the heater turned on high.
Just my 2 cents but sounds like your water pumps kickin it. Especially if you can hear the blend doors actuating.

As for the amount of fluid going into the heater core, I wouldn't imagine it would take much more than that amount of fluid. Evaporator is not very big at all, and most of what you see is just the fins. It's basically 1 tube that goes in the inlet, turns and comes out the outlet.. simple U shaped design, likely less than a foot long..

Yes proper fluids have always been used. Parking on an incline assist in getting any trapped air out of the system. It's not hard hearing the doors and actuator movement. Open your glove box fully, push in the tabs to allow it to drop out of the way, put your ear in that area and move your heat selector.

So you think the system is closed, single tube from in to out, no alternate path for fluid to run from in to out except completely through the full core?

 

[JBDive]

You must be registered for see images attach

What your heater core looks like(basic idea,Inlet/outlet tubes are slightly different).The coolant will flow just fine through it even when clogged.

So like most radiators the inlet tube isn't a single path to the outlet tube but there is an open area across the top where fluids can avoid the tube path through the coils but and just head straight over to the outlet? If so then that would seem to be a poor design as it would never allow for fluids to pass through all the coiled tubing and certainly would never flush.

 

[JBDive]

Drove around a bit this evening. Engine temps normal, outside temps 55. With heat on full, fan on nearly high (3) the temps coming out of vents stayed in the 115-120 range, while parked or driving at 45-50mph. (Laser Infrared Thermometer aimed into vents)

Won't be seeing even 30's except early mornings any time soon and I typically don't get out until after 10AM so might be awhile before I get to get some time at colder air temps to see if things hold in the 115-120 range as it was today after flush/fill.

Still would like a professional description of the design found in the Liberty heater core and it the water flow can avoid the coiled tubing and just exit the other end. Such a design would seem stupid but I don't see how I could have a free flow of air or water if clogged and fluid flow has to go in the inlet, flow through all the coiled tubes then out the outlet.The small amount of antifreeze I was able to directly pour into the core also throws me.

This image from an Autozone replacement would seem to show the inlet/outlet tubes are directly connected to the tubes that run through the core.

You must be registered for see images attach

 

[tjkj2002]

So like most radiators the inlet tube isn't a single path to the outlet tube but there is an open area across the top where fluids can avoid the tube path through the coils but and just head straight over to the outlet? If so then that would seem to be a poor design as it would never allow for fluids to pass through all the coiled tubing and certainly would never flush.

While you think it's a poor design it's really not,and yes it does suck that it can't be "flushed" but almost everything these days can't be.

By the way one gasket is one less gasket that may start leaking compared to the way you'd want it built.

 

[GunnerSchenck]

Not gunna lie, wasn't 100% on my info at the end of my comment about the heater core and wasn't home to look at my spare , but figured if I posted that someone may chime in and correct me (thus hopefully supplying the needed information).
I hope that your problem gets fixed soon! I have a spare brand new heater core sitting in my garage, had it for about a year waiting for mine to kick it lol.
I'm sure I'll do it whenever I have a better reason to remove the dash, or when it begins to go bad.
By the way, when doing it.. if you make a good how-to, I don't believe there's an informative one yet fully completed..

 

[JBDive]

While you think it's a poor design it's really not,and yes it does suck that it can't be "flushed" but almost everything these days can't be.

By the way one gasket is one less gasket that may start leaking compared to the way you'd want it built.

There would be no gasket difference. Not sure you get what I am referring to.

My assumption is the heater core would have an inlet which then flows through the tubes as they are coiled up and down to the outlet. Basically same design as an old school room heater radiator. If this was the case then back flushing would have no choice but to push out anything inside as the water would have nowhere to go but in the outlet, through the tubes and out the inlet.
Example

You must be registered for see images

If however the unit is designed as a radiator is then coolant flows in, picks the path of least resistance to the outlet. In a radiator if the radiator pores are clogged the coolant may or may not flow through the radiator proper but just around it finding the path of least resistance thus cooling suffers.

So i repeat my question, how is it designed and can the coiled tubes be clogged and allow for coolant to just skip that path and head right over to the outlet?

 

[JBDive]

Not gunna lie, wasn't 100% on my info at the end of my comment about the heater core and wasn't home to look at my spare , but figured if I posted that someone may chime in and correct me (thus hopefully supplying the needed information).
I hope that your problem gets fixed soon! I have a spare brand new heater core sitting in my garage, had it for about a year waiting for mine to kick it lol.
I'm sure I'll do it whenever I have a better reason to remove the dash, or when it begins to go bad.
By the way, when doing it.. if you make a good how-to, I don't believe there's an informative one yet fully completed..

If you get home and can take a look to see if you think it is a coiled system vs. a radiator style system - see my other post - and could comment that would be great. Images even better. Do you have a Mopar part or OEM replacement as they may actually be different in design, doubtful but possible.

I spoke with local dealer's service department and asked them for a repair quote (email it to me) and told them up front that if they were going to come in at $1200 then don't bother as I don't put that kind of money into a 14 year old vehicle no matter how well it runs, looks and so forth. I've only got 140k miles on it but age alone starts making things break in bulk. There's not another vehicle out there that I like and provides the features of the Liberty but dropping major bucks into 14 year old vehicles can quickly turn to just stupid. While I could likely take out the dash myself and do this job there are concerns in starting up such a large project in the garage, top of that list is having another vehicle to drive while the Liberty is torn apart.

 

[tjkj2002]

There would be no gasket difference. Not sure you get what I am referring to.

My assumption is the heater core would have an inlet which then flows through the tubes as they are coiled up and down to the outlet. Basically same design as an old school room heater radiator. If this was the case then back flushing would have no choice but to push out anything inside as the water would have nowhere to go but in the outlet, through the tubes and out the inlet.
Example

You must be registered for see images

If however the unit is designed as a radiator is then coolant flows in, picks the path of least resistance to the outlet. In a radiator if the radiator pores are clogged the coolant may or may not flow through the radiator proper but just around it finding the path of least resistance thus cooling suffers.

So i repeat my question, how is it designed and can the coiled tubes be clogged and allow for coolant to just skip that path and head right over to the outlet?

That is a highly inefficient way to design a heater core.You wouldn't get any better heat then a partially clogged current design heater core.

 

[GunnerSchenck]

Do your homework you can get it done in a day, two if taking your time, and save... A LOT of that 1200.

But I'm pretty sure every person on here has dropped that dough into their liberty at one point in time or another.. of they havent, I'll be willing to bet, they've put well over that price worth of time into it themselves..
I'll see what I can do about a photo here shortly.. pretty sure it's hidden in my mustangs parts in the garage somewhere lol.
It's aftermarket I'm pretty sure, but will try to find the make of it when I dig it out to let you know for sure. If I don't see any stamps, I'll go back through online and find the receipt and let you know the manufacturer/design.