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Heater core flows only in one direction

iwannabfishn

iwannabfishn

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I have a 68 coronet that had factory AC. The heater core is completely stopped up. There is no flow at all. I tried flushing with a regular garden hose but that didn't do anything. I hooked it up backward and tried to back flush it. That gets a trickle through it. Any idea why I can get flow backwards but not through the correct routing? I feel something blocking the exit if I feel around in there with a screw driver, but before I start randomly ramming a screw driver into my heater core I want to check and see if there is suppose to be something in there.
It's spring so I don't need heat, but I would really like to get it working again. Thanks for any information!
 
Go to the parts store, take the heater core with you, buy a new one, give them the old one as a core. Pressure test new one prior to installing.
 
Are you really going to trust this heater core. If I pull a heater box, I'll throw away the heater core anyways. I've never had an A/C car, but I sure the effort is even more to get that out.

I'm a thrifty guy, I ain't gonna make dat miztake!
 
I would try something like CLR in the core and let it soak then continue the back and forth with backflushing. If it still won't flush pull it out and send it to GlenRay for a rebuild. The new cores (at least for non a/c cars have shorter inlet and outlet tubes and are a pain to install.
 
My guess is you have a lot of corrosion and build up in that that has layered up over the years until it plugs it off. As for why you get flow the opposite way, think of a flapper valve in a toilet. I'm guessing you have a large flake of corrosion or buildup trapped by the exit of the coil. It presses against the exit in normal flow, but it can lift away from the exit when you reverse flow.

Get a new one!!
 
threewood said:
I would try something like CLR in the core and let it soak then continue the back and forth with backflushing. If it still won't flush pull it out and send it to GlenRay for a rebuild. The new cores (at least for non a/c cars have shorter inlet and outlet tubes and are a pain to install.
Click to expand...
I have found several new cores (rebuilds, mostly by A1 Crapdone) leak right out of the box. Quality can be poor.
 
rlem1977 said:
I have found several new cores (rebuilds, mostly by A1 Crapdone) leak right out of the box. Quality can be poor.
Click to expand...

I have seen a few and they all have the short pipes, they just can't get it right. My radiator guy checked it for leaks before I installed it. I have one in my 69 that came straight from Mexico and those fittings were a pain to install. But my original is on its way back from GlenRays for around $135 :)
 
Thanks for the info. The new heater core is $230 and my understanding is it is a bear to replace on the cars with AC. It isn't leaking at the moment. I may try soaking it in clr and see if it helps. If it causes it to leak then it will force me to replace it.
 
It's a real pain in the ***. You must remove the heater/ac box.
Which involves removing the seats/ counsel and unhooking and tagging everything.
Also unhooking everything from inside the engine compartment.
If you have a motor in place it makes it even more difficult.
Then the disassemble/overhaul/reassemble of the box is tedious to say the least.
Then reinstalling the box to the car.... more cursing.
Not trying to discourage you, but it's a real chore. Lol
Also, don't throw the old core away, fix it.
The old cores (like many remain parts today) aren't as good as the original and sometimes won't fit proper.

As far as the core goes, any competent radiator repair shop can clean it fix and pressure test it.
I got mine done for less than $100.

There are several good threads in this forum pertaining to the subject should you choose to overhaul your heater/ac box
 
Yeah try the CLR soak then put some compressed air to it. Not more than 30 psi should be safe. Going to need replaced sooner or later so roll the dice and you might get lucky.
 
somewhat related........... did my ram. royal pain the ***. if i wasn't so short on time (i think i'm part russian), i shoulda sliced an access port thru the firewall for both coils and patched with sheet metal.
ram took me the better part of 2 days.
i hate to think about doing one in my durango.
the coronet, there seems to be enough room, non a/c car
the journey, fergettaboutit!
 
iwannabfishn said:
Thanks for the info. The new heater core is $230 and my understanding is it is a bear to replace on the cars with AC. It isn't leaking at the moment. I may try soaking it in clr and see if it helps. If it causes it to leak then it will force me to replace it.
Click to expand...
Listen to kryslerkid & check for a valve. CLR (acid) is a reasonable idea. If it were me? I'd replace it... $54 Autozone https://www.autozone.com/cooling-he...e/spectra-premium-heater-core/845545_0_0_6774
 
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