Failed Heater Core - FOUR TIMES

[bradlogan]

There is no way 4 Cores went bad in that short a period of time, especially given they were all different makes and the last is OEM. Bad PH, etc doesn't eat a core in 30 days. I would check the pressure in the system as that being too high could be part of the issue. Even if the pump was putting out too much pressure the rad cap should vent it so I would test the cap. If the cap is not venting at the right pressure and holding too much pressure in the system that could be part of what is causing the leak. In all likelyhood however, your recurring leak is the hoses that attach to the core. Fix those and the core won't leak any more.

i know! to confirm you mean the hoses from the water pump to the engine wall, yes? and yes on the rad cap pressure test.

 

[Dean2]

i know! to confirm you mean the hoses from the water pump to the engine wall, yes? and yes on the rad cap pressure test.

Replace both sets of hoses. Do the hoses to and from the firewall on the engine side, and from the firewall on the inside, to the heater core and back to the firewall. Also check that the tubes that pass through the firewall are not leaking and don't have any holes in them..

 

[bradlogan]

i know! to confirm you mean the hoses from the water pump to the engine wall, yes? and yes on the rad cap pressure test.

BTW, if you mean the hoses from the water pump, but HOW could they cause the core to fail?

 

[bradlogan]

Replace both sets of hoses. Do the hoses to and from the firewall, and from the firewall on the inside, to the heater core.

I thought the hoses from the core to the fire wall were permanently fixed/ welded @ the core?

 

[Daw14]

Other common factor is the mechanic ???

 

[Dean2]

I thought the hoses from the core to the fire wall were permanently fixed/ welded @ the core?

Some are, some aren't. Most ofthe Ram cores are fixed, non-flex tubes from the core to the firewall. Problem is, because a new heater core can be tricky to install using the fixed hoses, many shops short cut it by cutting them and putting in a piece of rubber hose. Definitely not the right way, but very common unfortunately.

 

[Sherman Bird]

Hello,
New to forum, desperate for some insight.
I have a 2016 1500, Hemi 5.7. I bought it in 2020. Purchased with about 115,00 KM / 71,000 miles. it has 240,000km/ 149,000miles. The truck and I are in a love/hate relationship. Here is the latest issue. yesterday, the heater core has failed for the FOURTH TIME since January 2023. yup, less than 6 months. my local garage has dealt with it each time (they have just a hate relationship with my truck). background. my water pump started leaking during winter of 2021/2022, but because was laid off due to covid I couldn't fix it. I had heat, barely, so just drove the truck only when needed. I finally was able to replace the water pump in Jan 2023. Did myself, had no known issues, to me anyways, when I replaced it. About two weeks after replacing the water pump, the heater core went, so late Jan 2023, was the first time. Took it to the garage as it was too big of project that I wanted to do. They replaced with after market. Later Feb 2023, it failed and they replaced with different after market. April 2023, it failed again, they replaced with a dodge heater core. And now July 2023, THAT dodge heater core has just failed. They are at a loss as to why or how it could fail so many times. Obviously they are getting tired of doing this work for free, and I'm getting tired of taking it to them.

Any theories or suggestions on what we are missing that could result in four heater cores failing in short order? The heater core is not rocket science, but good grief something is "chewing them up".

Thank

 

[Sherman Bird]

Have you replaced the blower motor recently???

 

[BadHemi2014]

I replaced my heater core in my '16 back in January of 2021 (that was fun, let me tell ya). Mine wasn't leaking (yet) but I was getting barely any heat (ironically, since it's been tuned and runs cooler I only get lukewarm heat again...anyway--) Here's some pics, not the greatest but might give you some ideas of whats going on.
Here's a pic of the entire box out on the ground. The heater core is the shiny thing right in the middle. The heater core has aluminum tubes that go through the firewall and attach to your heater hoses on the engine bay side of the 'wall.


Here's a closer view of the core. You can see I cut the heater hoses just before the firewall. They're in a hell of a tight spot to unclamp and I knew I'd be replacing them anyway. I wish I'd taken a pic from another angle but it seems like no matter how many shots you take you never get the one you need lol.




Here's a pic of it pulled out. The tubes are part of the core. Where they attach to the core itself could be a failure point.


Here's one more shot of where the heater hoses attach to the core's tubes at the firewall. If these hoses are original that's insane, they should have been changed with the first core. No reason not to. It's something you only want to do once they are waaay back in there. Hard to even get a pic of.



So as you can see it seems the only failure can be the heater core itself, or possibly where it's tubes connect to the core itself, or less likely where the heater hoses connect to the aluminum tubes, although as you suspect that would be more likely to cause a slow leak into the engine bay. But again if those hoses are old, the leak might have started there, coolant can definitely flow into the cab side of the firewall from there.
I can't really figure out how four could leak in a row. It's a pain to pull the dash but it's not technically difficult. I did the whole thing myself other than a little help at the end just to hold the steering column up while I bolted it back in place. I mean you just pull the dash, pull the hvac box, disconnect the heater hoses (ideally from firewall side if you can, there's not much leeway to pull them through the 'wall), take the old core out, put the new one in, connect the heater hoses and put everything back.

 

[Sherman Bird]

I can tell you a definite way that 4 or 5 cores can fail in short order. It's called coolant "electrolysis" or it is from the blower ionizing the air as it blows against the first core it come to.... the heater core.

Electrolysis is from coolant which is either the wrong stuff, and/or failing to put distilled water in the system after a thorough flush following repairs or during maintenance.

Sometimes, blower motors can ion charge the airstream. To diagnose that requires specialized tactics of diagnosis which is beyond most laypeople.

I've seen both failures over the past 5 decades in this profession.

 

[Burla]

Does most electrolysis come from bad grounds? Which in turn causes stray current?

 

[jws123]

You need to find yourself a new mechanic/shop clearly they dont know what they are doing.

 

[bradlogan]

Fascinating info! Since all h/c were of different manufactures, weak joints is highly unlikely. reusing coolant, LOL! except for this time, most of it leaked out. I believe, though not certain, that whatever coolant was in rad, was just added to, vs flushed. I have no signs of a head gasket issues. Oil was just changed - just black. No coolant loss, no over heating, no smoke, no gurgling. I think idle is fine, i have a cracked exhaust manifold so the sound from that is somewhat distracting. But generally once the engine is warmed up, my idle is just fine. besides, on the pressure front, wouldn't the rad gasket blow if my pressure was to high? I will check the PH and confirm the pressure.

About the gurgling. I do not have in the morning. But after driving on and off for about an hour (starting and stopping engine several times at various stops), at one stop there was some gurgling. To confirm engine is fully warmed up. And right now we have bypassed the heater core. So
Coolant goes out water pump and then immediately back in

 

[sig25]

If it were me, I would go ahead and replace the radiator cap. Radiator caps are rated in PSI. They control the pressure inside the system. That said, I would get one from the dealer to ensure that it is the proper PSI designated for your truck. There is a way to check the cap to make sure it is working but that requires special test equipment. The last I knew, it wasn’t a super accurate way to test but maybe technology has changed.

 

[greg mayrhofer]

I had similar problems with my 02 dodge ram,little or no heat, no leaks though, it turned out the heater hose to the heater core to the water pump were placed in the wrong outlet, in and out, reversed then then burbled the rad to get all air out, and road tested good, heat was back. part of this may be your problem i dont see that many heater cores all failing, especially the last one from mopar. and was mentioned by another member the rad cap seal or spring presure might be on the way out.

 

[Burla]

OP easy to test coolant for electrolysis.

Test coolant for electrolysis​

Set a digital multimeter on the DC scale for around 12 volts. Attach one of the test leads to the negative battery terminal and submerse the other end into the coolant. Then rev the engine to 2,000 RPM and read the voltage on the meter.



If the coolant test reads over .3-.4 volts, it means that the coolant is conducting too much electricity. Either the coolant needs replacing or you have a grounding problem in the vehicle. If the coolant is fresh, check for poor ground connections between the engine and the firewall and the engine and the negative battery terminal.

 

[Davis MacD]

I had a bearing break apart on my water pump and I am new to the dodge 4.7 with 16 spark plugs. It was an easy change out but later I noticed that the impeller was munched and wonder where the chunks went . Maybe your chunks went to a place where they jammed up coolant flow and create high pressure in your heater core.
Last winter homeless motorhomes swarmed the neighborhood and we threw cinderblocks into the flood drains to block the backroad into the neighborhood. If they tried to cross the artificial lake we created I would smash thru the lake that was 4 feet deep and 50 foot long. One time I hit the lake at 50 mph and flooded tents and knocked over all their ****. Real quick they learned to stay on their side and we let them stay until late June. Several of us are discovering that the impact of the water on the fan blades broke water pump bearings and munched impellers... but they were not leaking and the belt was holding things in place. If you do this kind of stuff regularly,.. I don't think our trucks are built to do this.

 

[Jeepwalker]

If you have gurgling, it would be a good idea to 1) squeeze your upper radiator hose when the vehicle is fully warmed up too see if it's rock hard under real high pressure. 2) Look into your radiator under the cap while a partner gives it a little throttle. Look for excessive bubbles in the coolant, and sniff for combustion odors. They make test strips that can ID a leaking head gasket, but a human nose is pretty sensitive too. If you smell combustion odors, even a little, then you know you're onto something. Obviously don't open the cap when it's under pressure (that would be insanely stupid). 3) If you *DO* observe #1 or #2, pull out the spark plugs and see if you have one that's real clean. If so, that could be the cylinder where the issue is.

Gurgling doesn't mean a leaking head gasket for sure, but it's a marker. It "could" be. A weak head gasket, but not really leaking much. Not enough to go through much coolant even. A h/g in it's early stages of becoming weak can sit fairly undetected for a few years in some cases. Esp if it's a situation where the head gasket is delaminating between it's layers. High pressures on the cooling system where the upper radiator hose is as tight as Toby's a&& can reek havoc on a heater core and/or the joints/hoses/couplers that connect to it. And also the water pump.

So what I'm saying is, check these things out bc it could be the 'root cause' of the problems you've been having. Perhaps not. But worth spending 15 min to rule out, and focus on the next possibility. Otherwise you might be chasing ghosts for a while. This is something 85% of mechanics replacing a water pump or heater core would likely overlook, and it won't show up on any scanner.

 

[Sherman Bird]

Electrolysis comes to mind. Coolant cavitation due to a bad cap is another. Perhaps someone replaced the heater hoses and inadvertently tossed the orifice/ restrictor.

It's kind of ironic that these failures began AFTER you replaced the pump.

The law of descending logic forces me to think that this problem is a result of some simple oversight, not necessarily a new "other" failure. IOW, what was last done before the problem began? Go back to that and really scrutinize the work of the shop. Good luck!

 

[Sherman Bird]

Has any one cut one of these heater core's apart to see what's going on inside? Are they leaking at the braze joints (or where?)? What's your water treatment look like?

Some possibilities could include:
1) pH totally out of whack. High ph eats aluminum. Guess what the thinnest aluminum part is? It doesn't mean it will eat a hole, all that's necessary is eating around a braze joint. Are they reusing your old coolant every time? Ask them to do a pH test. That should solve this question. Remember, coolant contains components to help reduce corrosivity, even if the pH measured is slightly outside of the 'safe' range. pH strips are terrible in accuracy, which is what most shops use. A good digital meter is much better...but must be properly calibrated or checked against a known set of pH buffers, of different known pH levels. Then you know your meter is reading properly. See charts below.
2) Bad engine ground and somehow the heater core has become the anode?
3) Too much pressure (Per Burla above). But to add ....it high pressure can be caused by a bad headgasket too. A headgasket can be 'semi-bad' for quite a while prior to a full-on white-out! LOL. How does the upper radiator hose feel when the truck is warm? Do you hear gurgling in the AM when you go to drive the truck? Do you smell combustion through the radiator? Bubbles in the coolant at higher rpm's.
4) 4 bad heater cores in a row. Unlikely, but certainly a possibility. Maybe there was a bad run of H/C's where braze joints are weak. Or the way they are packaged, they take too much abuse via shipping which weakens the inlet pipe braze joint.
5) Incompetent dealer tech getting 'rough' with the h/c during install.


These two charts say a lot: Aluminum is low nobility ...meaning it pretty freely gives up it's electrons compared to many metals (like Copper). And 2) Too high of a pH is good for iron, but not for Aluminum. Meaning a high pH will cause AL corrosion. In a mixed Iron/Aluminum system, a pH of aroud (or just under) 9.0 is within the narrow window for both metals. Copper core heater cores (like back in the old days), copper doesn't readily give up it's electrons (as easily). It could withstand coolant neglect a lot more.

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In 1997, I was working in a Chevy dealer where the tech right across from me installed 5 heater cores in a then newly redesigned Lumina car. This was 5 heater cores in about 2 months!
He had called GM Tech help line and he had tried everything except standing on his head and rubbing his belly, per his own knowledge and inputs from Tech Help.
The customer was screaming "Buy Back"! and that was the very last thing the General wanted. So, they called in GM's STG (Service Technology Group) gang. These were traveling engineer/ trouble shooters who were THE ultimate nerds!
I observed them hook up this car to so many electronic diagnostic gizmos, it appeared the car was on life support!

Eventually, they determined that the HVAC blower was ionizing the air stream across the heater and evaporator cores. Their temporary fix was to install a piece of metal window screen across the face of the heater core and attach a ground wire. The vendor who made the blower motor was Siemen's. GM contacted Siemen's, the blower was redesigned, and the car was called back some months later for a proper fix. The heater core was the first component in the airstream, so it did not affect the evaporator core, per the STG engineer.

My point is that one has to look at what seem like unlikely places. I'd begin with an electrolysis test. I'd also question what brand and type of coolant was used. Was distilled water used to prevent mineral contamination?