I must have something else going on with my antifreeze, as I've apparently just busted through my 2nd replacement heater core, so I'm about to be on my 3rd. Last time it started leaking was just after the Christmas Parade 2 years ago... I was thinking that possibly the antifreeze had gotten hot enough to melt one of the the sweatted joints on the heater core.. but I dunno... what temp is needed to melt the solder/braizing material used on those cores?

Leaking antifreeze dripping inside the passenger side floorboard... perma-haze on the windows, the whole schemil...

So.. what causes the heater cores to spring leaks? I just read through old messages on the forum and see references to the temp of the lines going into an out of the core... Here's what I just found when giving a cursory look at my heater core lines & antifreeze tank:

Temp gauge: Holds steady at about ~190 deg F. Thermostat was changed about a year ago (March 2005) while on a trip where it had gotten stuck open (so engine was running cool).

Heater core lines: Both supply and return lines are VERY hot to the touch. 20 minutes after I got home, the temp gause reads 150 Deg F., and I used a candy thermometer to give a surface temp reading of the heater core lines.. also reading ~ 150 Deg F. (again - this is after the car sat for about 20 minutes after getting home)

Reservoir tank: A bit low. I added about 1/2 gallon of water to bring the level up to "Full Hot" (as everything's still hot, and hasn't had time to cool down from this morning's trip to the post office). Lots of "floaties" floating around in the reservoir tank. I'm thinking there may be some scale buildup somewhere in the system...

Any ideas as to how I can prevent this again 2 years down the road? I know I've got a good 6 hours of work ahead of me to pull the dash & replace the core & put it all back together....

Thanks,
Rex S.
Richardson, Tx

 

Well.. Looks like I *may* be in luck. I hopped on the motorcycle and went to the local Home Depot, and picked up all I needed for the 3/4" to 5/8" bypass valve.. as I was planning on simply bypassing the heater core....

Got home, assembled all the parts, and pulled the heater hose line off of the core.. Looks like the 5/8" line may have had a small crack in it *right* where the spring-hose clamp holds the hose onto the core inlet nipple. I'm sure hoping that the hose was the leaky culpret, and it was simply dripping down along the outside of the heater core, and causing the drip inside the passenger compartment. I'll post more later after I've tested the theory.. and will probably p/u a new set of heater hoses at Auto Zone pretty quickly.

Rex S.

 

I would think even bad luck wouldn't make you go through heater cores like that, but I don't know. Changing the hoses is probably a good idea anyway, although a better idea if it fixes the problem.

 

Yeah, about as good a reason as any to explain what I do as a preventative to problems such as these. IF and this hardly ever happens, I change hoses completely when installing new, but if; I would cut off as much hose as it took to get to newer, better end, sometimes a couple of inches. Then would take a little silicone, blue goo whattever you like, and coat the metal thinly with it. Then slip over hose and clamp down.

Now this is if I am desperate and cant get hose. Not normal for me, cause I would normally replace both hoses and the odds would be REAL good that I would substitute a stainless set if they were available. Complete with clamps. I would still use the silicone gasket material at the metal end THINLY before slipping hose over. Think of it as protection against the inevitable.

I have ample reason for all this. I am poor and lazy. I cant afford the tow truck and NEVER want to get caught out in the middle of nowhere with problems; too lazy to walk.

BTW the bypass is still a good idea, but some vehicles DO depend on this as part of the cooling system, so watch the temp gauge right after you install a bypass.

 

Update.. Well, it IS the heater core that's leaking. I installed a bypass valve/tubing for the 3/4 to 5/8 lines to loop the inlet & outlet water. It ran fine (but was a COLD ride to work). I noticed it was a more drastic temp change when the thermostat opened/closed - but it never overheated or even came close - stayed at about 200 degF max during stop-n-go traffic.

So... I replaced the heater lines because I had found a *small* crack in one of them... Then hooked up the heater core again... and this morning took it for the test - about a 40 minute drive to work... Well, about 5-minutes into the drive I started smelling the antifreeze again, and sure enough, there was a pretty good drip coming down from the heater core into the passenger floorboard again.

Picked up another heater core at Auto Zone tonight, and will probably do the switch this weekend.. 'til then, it's got the bypass loop/valve in place again. I can live with the (mildly) cool weather. The only good news to report is that my LAST core was bought at Auto Zone as well - almost right at 2 years ago. The cores from AutoZone have a lifetime warranty on them, so they told me to bring the old one in once they're swapped, and they'll refund my money for the heater core. Sort of takes the bite out of the work...

I'll let you all know exactly where the core failed once it's been pulled. The first 2 had failed along the crimped/sweatted end caps. I wonder if there's some vibration or something that's weakening a joint... and it's "work hardened" - then cracks... We'll see...

Rex S.

 

That sucks man. If you can, take plenty of pics! If you have time, possibly write up a How-To and throw the pics into it (noting any difficulties you ran into as well). I'm going to try to make up a How-To section in the coming months.

Have you always bought your cores from Autozone? If so, I'd say there may be something wrong with the quality of those parts.

 

"The only good news to report is that my LAST core was bought at Auto Zone as well - almost right at 2 years ago. The cores from AutoZone have a lifetime warranty on them, "


Sorry to hear the bad news. had hope you would get lucky with the bad hose. I gave up on the "Life Time" stuff from Auto Zone. That just means you will be changing this part out for the rest of your life!

 

I really have never been impressed with any replacement part from Autozone. I have never had good luck with them.

 

I'm doing a little groundwork research for the purpose of not having to do this again in 2 years. In my research so far, I've found an article that lists electrolysis as thr number one killer of radiators and heater cores - fronm the inside out - even killing sweated fittings, etc...

Now, this is my highly simplified "Cliff's Notes" version, but: Apparently, if you have an insufficient ground, etc, then there's free electrons that get stored - and apparently antifreeze is a good "capacitor" to hold that charge.

The article says to use a digital voltmeter, and put the ground to the vehicle's ground (or grounded chassis), and the positive probe is to be placed into the antifreeze/coolant (without touching the core inside the radiator) - give it a few seconds to settle out, and if the voltmeter shows more then .3 volts then there's a good posibility that electrolysis can be affecting metal that's in contact with the cooling system.

Here's a link to the original article - which is interestingly enough - linked to from the manufacturer of MY heater core.

http://www.pliii.com/documents/electolysis91004.pdf

That said.. Yes - I'll take pics and document the process of changing out the core ths weekend.

Rex S.

 

Only old antifreeze will show you a high voltage. Dis-similiar metals and any liquid will cause elctrolsys. The higher the acid content of the liquid the higher the voltage.

I think that a more correct answer would be the Auto Zone heater core. They buy the cheapest stuff so they can sell the cheapest stuff to you.

Solder starts to melt at around 450 degrees if I remember correctly. Far above the temp your coolant reaches.