eater Core questions (yeah as always)

[GunnerSchenck]

Rite 'cher she is!
For now I'd call it "definitely not oem"
Btw.. I got mine because it's slightly plugged up but still works fine, if it's was a single coil cooling tube design one like your picture or that I mentioned previously.. I probably would've had to put this in by now.. :happy175: been sitting here waiting for the other to get bad enough for this replacement to be worth it lol

 

[JBDive]

Rite 'cher she is!
For now I'd call it "definitely not oem"
Btw.. I got mine because it's slightly plugged up but still works fine, if it's was a single coil cooling tube design one like your picture or that I mentioned previously.. I probably would've had to put this in by now.. :happy175: been sitting here waiting for the other to get bad enough for this replacement to be worth it lol

So you think from looking at your unit that fluid can bypass the coiled tubes and just go from inlet to outlet? You expect the OEM version to do the same then? If so then this is what I'm saying is a poor design because even when new there would not be full, even flow through the entire unit as any fluid is always going to take the path of least resistance and a bend in tubing by default creates restriction.

 

[GunnerSchenck]

Give me a second and I'll put up a picture to explain to go with this post.

1. No I don't believe so?
2. It's the same as OEM yes, but still refer to 1. (No)
3. Not a poor design by any means as there are 12 cooling tubes which run from top to bottom and back up.
Even if some were plugged, there would be coolant flow through the others.
The coolant cannot bypass itself from one cooling tube to the other..
4....if the bend was enough to restrict flow, I'm sure they wouldn't do it on every cooling tube you'll see. Even the coil version you illustrated has bends (many in fact) and although gravity would help it, this is MUCH more likely to plug up, and flow from one side to the other would take much longer as well.


Perhaps I don't understand your question correctly, but technically there's like 1/12 of the chance of it being plugged as opposed to 1 single coil...


Also, your picture of the top of the Auto zone replacement is correct. It goes in the right tube, distribute to all 12 cooling tubes, they go downward to the bottom of the heater core, and all come back up and meet at the left tube..
They are separate in a sort of front/back rows. Don't directly connect to each other..at least I don't believe. they connect through the tubes, which are cooled as they run across the fins.

 

[GunnerSchenck]

Hopefully this helps a bit.. either way it's what's in your jeep.. no changing the design now lol and good luck. Feel free to check back if you need help with the install!

 

[JBDive]

Hopefully this helps a bit.. either way it's what's in your jeep.. no changing the design now lol and good luck. Feel free to check back if you need help with the install!

No I get that the coolant is designed to flow into and through the tubes, no different than your home A/C unit. What I'm saying though if there is a path between inlet and outlet that can bypass the tubes then even if they were not clogged the coolant would always take the bypass as it's the path of least resistance. Allowing the coolant to flow in any path other than through the tubes would be a poor design, curves/bends are restrictions, a straight path is not.

So my question stands either because I am not getting what is being said or it has not been said. If the tubes are blocked can fluid run from inlet to outlet?

So in the very crude drawing below, coolant enters on left, it tries to enter the tubes to flow down and around but can't and just runs across top and exits never heating up the coils/fins. Is this how it works or is coolant forced to enter at some point and can never get to the outlet without going through a tube/coil?

You must be registered for see images

 

[GunnerSchenck]

I was under the impression it operated like this (with 12 tubes rather than 4, but for drawing's sake). So my apologies as I didn't realize the inlet and outlet are connected above the cooling tubes, allowing it to not flow through the tubes if they're clogged. I get what you mean now. But still seems a smarter design to me, even if you can't properly flush it.
Still, as I said. Can't change the design now.

 

[GunnerSchenck]

So my question stands either because I am not getting what is being said or it has not been said. If the tubes are blocked can fluid run from inlet to outlet?

They appeared to be seperate, but I suppose this would make sense. Kinda as a failsafe, rather than keeping coolant flow from cutting off and not coming out the outlet side in the event of blockage.. would you rather have coolant that's slightly too warm, or no coolant flow in the event of blockage?

 

[GunnerSchenck]

What I'm saying though if there is a path between inlet and outlet that can bypass the tubes then even if they were not clogged the coolant would always take the bypass as it's the path of least resistance.

Even if there was, the cooling system is pressurized, so fluid would be forced to fill all of it anyways.. not choose one or the other. Just if it is designed this way(my apoligies as i didnt think it was by visually looking at it) but if it is.. like I said, seems like a failsafe..

 

[JBDive]

Even if there was, the cooling system is pressurized, so fluid would be forced to fill all of it anyways.. not choose one or the other. Just if it is designed this way(my apoligies as i didnt think it was by visually looking at it) but if it is.. like I said, seems like a failsafe..

Problem is though if my drawing is correct and yours is incorrect then while coolant would certainly flow into all the tubes and it would warm, it would not flow evenly because as I said a fluid will always take the path of least resistance. Sure the tubes would be forced to fill but not forced to flow. Convection may heat the fluid at the bottom of the tubes but fluid itself may never fully flow through it because the fluid can run right across the top and out. The other problem of course being a reverse flush is going to do the same thing, avoid the tubes and head straight for the nearest exit.

This is also going to lead to crap collecting in the bottom of every tube where it bends as this is a natural restriction to flow so both flow speed and gravity are going to work at creating deposits there.

So we are on the same page at this point, my crude drawing is correct, the inlet and outlet have a direct path which means the tubes could be avoided?

 

[JBDive]

They appeared to be seperate, but I suppose this would make sense. Kinda as a failsafe, rather than keeping coolant flow from cutting off and not coming out the outlet side in the event of blockage.. would you rather have coolant that's slightly too warm, or no coolant flow in the event of blockage?

One of the first things everyone says when checking to see if the core is clogged is to check your temps of both hoses. The fact that both hoses are nearly the same temp (10 degrees difference) says fluid is still running through which I proved with flushing. So what I was asking was does this actually prove the core is clogged or not and I think the answer at this point is NOT.

If the core became clogged and the flow was restricted to the tubes only which would then cause no flow from inlet to outlet I don't think this would be a problem where you would see catastrophic failure of the cooling system. The flow to the heater core is a bypass from the system as a whole so cooling would still take place it just couldn't make that small low pressure loop through the core. Remember that older cars actually cut off flow to the heater core through a valve when the heat was turned off so we know flow is not required. The design change from that was to stop cores from becoming clogged due to long summer months of crap just sitting in the core, plus I am sure it's cheaper to build without the shutoff valve.

 

[JBDive]

Well I will close this thread out unless someone has something really constructive to add.

I risked the deer and took a little 10 mile loop on the highway tonight. Speeds 65-70, temps 38-42. Heat coming from vents stayed in the same 115-120 range with fan running on 2 out of 4 which is where I would normally run it anyway as higher is to loud unless I have it on my feet trying to dry out boot or something.

So I give, clogged or not clogged? Clearly it's not the blend door as first off I said I can hear it open and close but if it were not closing then I would have seen a difference in vent temps with outside air in the mid 50's and outside air in the 38-42 range and I didn't. I don't think it's as hot as it was in the past but 120 is a tripling of outside air at 40 degrees. I've got an email into the local Jeep service center asking for more input so if they provide anything useful I will add that later. Their job quote for replacing was right in that $1200 range as expected which I just don't see putting into an 02.

 

[GunnerSchenck]

If youre that convinced that it's the heater core, just change it.. Takes a day and $130.90 on moparpartsoverstock for an OEM heater core.
Guessing you have had cross contaminated HOAT coolant, or a rare circumstance arose allowing the heater core to completely clog.
If the whole heater core is clogged other than that bypass zone, I'd imagine your problem lies somewhere deeper, as the core didn't clog itself lol
Good luck, and update to let us know if the heater core fixes the heat or just for about a month. If so.. id still be leaning towards your water pump.
No heat = bad water pump.
And I'd assume it doesn't overheat on the gauge or you'd already be leaning there.
But in the 3 waterpumps I've had to throw at my jeep, not a single one has allowed it to overheat. Only time it ever did was from air trapped in the cooling system.

Once again, good luck.

 

[JBDive]

If youre that convinced that it's the heater core, just change it.. Takes a day and $130.90 on moparpartsoverstock for an OEM heater core.
Guessing you have had cross contaminated HOAT coolant, or a rare circumstance arose allowing the heater core to completely clog.
If the whole heater core is clogged other than that bypass zone, I'd imagine your problem lies somewhere deeper, as the core didn't clog itself lol
Good luck, and update to let us know if the heater core fixes the heat or just for about a month. If so.. id still be leaning towards your water pump.
No heat = bad water pump.
And I'd assume it doesn't overheat on the gauge or you'd already be leaning there.
But in the 3 waterpumps I've had to throw at my jeep, not a single one has allowed it to overheat. Only time it ever did was from air trapped in the cooling system.

Once again, good luck.

No way coolant was ever mixed. Only three places have serviced my Jeep other than tires/wheels and that is Dealer, Me and the radiator shop where we discussed multiple times the need for HOAT and he even confirmed he had gone and got some from the dealer just for my job since I was so adamant about it being Mopar HOAT.

I really can't get into a job that takes a full day or more to complete and pulling the dash is every bit of that if you haven't done it before. Its really a last worse option other than paying $1400 to have it done when I am still not convinced it is the heater core.

This week I have been roasting in the Liberty and temps have been in the 40's or lower. I was seeing colder air on one day, especially when putting it on defrost or defrost/floor but later that day it warmed right back up. Air vent temps running 115-140.

A water pump that just isn't pushing as much water as before but still more than enough to keep the temp gauge in the same place as always, just a tick off the middle hash, maybe. Would be the first time I've seen that and not see any other signs of a failing pump (leaks, overheating, noise, etc). That said though I did notice on the coldest day this week when I was just sitting in a parking lot for an extended time with the Jeep running the vent heat temps dropped significantly. Temp gauge stayed the same the entire time so you may be on to something and I would be more likely to pull the thermostat and water pump before I went for the all out job of the heater core. Both appear to be rather easy with easy access on the Jeep which seems to be uncommon in cars today.

 

[fastcarsspeed]

You could try this technique? https://www.youtube.com/watch?v=YccsacgUJPI

 

[GunnerSchenck]

All I was saying, is a heater core that has clean HOAT coolant flowing through it at all times, doesn't clog itself.
I understand the time part of the dash, was simply trying to say it's not too intimidating once you've got into it. Hardest part is dropping the column and it's actually not bad either. I usually draw a mark around the mounting nuts for it so you know it's exactly where it was. Also a good time to regrease your steering shafts and joints.
I may not have done my dash myself, but I have on many cars, as well as my friends 04. Usually the processes (and even mounting points) are relatively similar. Only difference with jeeps is they come apart easier IMO. All tends to weight less and be more compact as well. As you've already noticed with the glove box (checking the blend door whether its being actuated) and how easy it is to remove.
Was simply trying to let you know it's doable. Especially with info found in the searches on this site (just no definite how-to).

The water pump, if youd rather do first, there is a definite how-to as well as many threads and info on. Quick and easy, and you can you a reman from Napa that plenty have had success with but I went Mopar.
Thermostat, definitely Mopar.
I had shifty heat with my last water pump pretty bad, would only work when I was driving and would get hotter as I accelerated. When I came to a stop I had to turn it off or feel the temperature of outside blowing at me at whatever selection I was on(in winter it would turn to basically AC temp in your face at a red light).

Now I've never bothered using my infrared digital thermometer to check the temperatures of the heater hoses, nor vent temperature so that's the only reason I didn't try to relate to that info.

This was all just just personal relative information. As well as an attempt to save you money and hopefully grief.

My professional opinion would be, if it seems like 1400 would be easier to pay for it, then do that. At least then they can be there in person to run the necessary diagnostics themselves and confirm the issue beforehand.

Btw when my heat was bad enough to be that cold at a stop.. it was to hot to directly point at you at highway speeds.

 

[fastcarsspeed]

Gunner,

I tend to disagree. HOAT degrades over time like every other coolant and I have seen is scale very bad in Chrysler engines. I just worked on my daughters 04 Neon and at 180K miles the coolant had been replaced at least once that I know of with a waterpump, timing belt change. The scaling was soo bad that I could not save the radiator but was able to flush the heater core enough to get it to heat for here in MD.

 

[GunnerSchenck]

Gunner,

I tend to disagree. HOAT degrades over time like every other coolant and I have seen is scale very bad in Chrysler engines. I just worked on my daughters 04 Neon and at 180K miles the coolant had been replaced at least once that I know of with a waterpump, timing belt change. The scaling was soo bad that I could not save the radiator but was able to flush the heater core enough to get it to heat for here in MD.

That's not the proper service interval to define the coolant at clean uncontaminated fluid. How many times should it have been changed in 180k?

Even if that's true, that's an inconclusive example and a fallacy.

 

[tommudd]

Changed once in 180,000 miles, well duh
Not being a smart a** but come on now got to be changed more often than that !
By the time my 04 had that many miles had been changed 4 times or maybe 5 have to look at the records

 

[GunnerSchenck]

Thank you. It's 60k intervals recommended, and I do mine every time I do my spark plugs..cuz eh, why not.
Even if it was under warranty it probably would've only gotten changed at 60k before that warranty expired. So if it was only changed once that you know of after. That means there's a possibility that coolant was run for what, 120k? An extra 60k on your coolant life could easily cause premature water pump damage, and in your case be bad enough to mess your radiator up with it..

Because as you stated, all coolant degrades over time. Thus creating the need for the service intervals which must be followed.
If anything the only fact that's being supported by the example, is my statement that clean HOAT coolant will not cause your heater core to clog itself.

 

[GunnerSchenck]

A water pump that just isn't pushing as much water as before but still more than enough to keep the temp gauge in the same place as always, just a tick off the middle hash, maybe. Would be the first time I've seen that and not see any other signs of a failing pump (leaks, overheating, noise, etc). That said though I did notice on the coldest day this week when I was just sitting in a parking lot for an extended time with the Jeep running the vent heat temps dropped significantly. Temp gauge stayed the same the entire time so you may be on to something and I would be more likely to pull the thermostat and water pump before I went for the all out job of the heater core. Both appear to be rather easy with easy access on the Jeep which seems to be uncommon in cars today.

Just to let you know how much of idiot gauges the temp gauges actually are, if you look through the recent threads for "coolant flow", there's a guy running a radiator dry with no coolant in it, and his temperature gauge has not changed or fluctuated. He's also running the incorrect coolant, and once more the temperature gauge has not changed.
So it may be the first you've heard of it, but even in my own example of my jeep.. the problem was obviously more drastic, but once more.. my temperature gauge did not change or fluctuate. When I broke my radiator and it gushed all over the road, my temperature gauge once more.... did not fluctuate.

The only time mine has changed, was air in the system and it only showed change at highway speeds. I'd get off the highway and the gauge behaved normal.. get back on, and it would actually start moving to the Cold side. Pulled off the highway, and purged the air a couple times from the bleeder screw and it went away.