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Removing Heater A/C Box and Have Questions

6T8 Charger

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I got my 383 Charger running yesterday and noticed steam coming from the defrost vents. I knew that wasn't good. I let the motor run until the thermostat opened (which it did!) and then looked inside the car to see coolant dripping down from the heater box and puddling on bare floorboards (car had no carpet or interior installed). I don't see how I can replace the heater core without removing the entire box. I removed the heater control valve and the 4 nuts that secure the box to the firewall and it started to come out but if feels like something on driver side is hanging up and stopping it. I have removed much of the dash stuff like the glove box, gauge pod, heater controls, radio, etc. Any suggestions? TY
 
The entire box does not need to be removed, just the front half (piece with defroster outlets). The service manual details the process. The Heater core is attached to the front half. Its a tough job but doable. When you have heater core out, send it to Glen Ray for repair, as none of the aftermarket fit properly. Taking the heater control valve out is not necessary, but when removing you are probably feeling the control cable or capillary tube wire holding it back a bit. When you have front of box off that is the time to do any underdash work because it does afford you quite a bit more room (like replacing dash wiring including bulkhead)
 
The entire box does not need to be removed, just the front half (piece with defroster outlets). The service manual details the process. The Heater core is attached to the front half. Its a tough job but doable. When you have heater core out, send it to Glen Ray for repair, as none of the aftermarket fit properly. Taking the heater control valve out is not necessary, but when removing you are probably feeling the control cable or capillary tube wire holding it back a bit. When you have front of box off that is the time to do any underdash work because it does afford you quite a bit more room (like replacing dash wiring including bulkhead)
My service manual showed up in the mail box after I posted this. It says to remove the front cover of the case and the heater core will come out, so I will try that. Once I get the core out, I will need Glen Ray's contact information. Thank you LBM!
 
There are more leak points than just the core. The core might be fine. There are o-rings on the end of the supply pipes on right side, another valve inside and a short piece of 5/8” heater hose or two.

You won’t believe what you will be seeing insode there.
 
There are more leak points than just the core. The core might be fine. There are o-rings on the end of the supply pipes on right side, another valve inside and a short piece of 5/8” heater hose or two.

You won’t believe what you will be seeing insode there.
I'm in the process of taking the front cover off the case and there's vacuum hoses and linkages everywhere, all kinds of good stuff! I can already see there were some critters nesting inside the a/c door by the heater core. This should be interesting.
 
I pulled the cover off the case and it was kinda disgusting. Mice had taken up residence and there was all kinds of gross inside the case. I found acorns, a Bic lighter and a chrome lug nut in there (plus all the mouse droppings)! An old hair brush was lodged inside the ducting. My defrost dash vents are broken so I think things could fall all the way down inside the unit. It's bad. I have removed the entire case for cleaning.

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I got my 383 Charger running yesterday and noticed steam coming from the defrost vents. I knew that wasn't good. I let the motor run until the thermostat opened (which it did!) and then looked inside the car to see coolant dripping down from the heater box and puddling on bare floorboards (car had no carpet or interior installed). I don't see how I can replace the heater core without removing the entire box. I removed the heater control valve and the 4 nuts that secure the box to the firewall and it started to come out but if feels like something on driver side is hanging up and stopping it. I have removed much of the dash stuff like the glove box, gauge pod, heater controls, radio, etc. Any suggestions? TY

If you have no interior, take the whole sucker out and rebuild it completely. Kit from DMT is awesome and it will get that thing fresh and complete. Obviously you may need a new core......but not chunk the old one.....keep it for comparison........non A/C car? If A/C....then the rebuild will be more in depth......but also very straight forward........
 
Contacted Glen-ray Radiators. $400 for heater re-core. He also suggested that I send the a/c evaporator so he can pressure test it. He says that most of the time they're fine but while I've got the entire unit out, it sounds like a good idea. $50 for that. So total with shipping probably $550 which seems reasonable.
Turnaround time is 3 to 4 weeks.
The guy was nice and very helpful on the phone, I was impressed.
 
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Now is also a good time to determine if the water valve on the firewall functions and have it rebuilt if necessary. It most likely leaks internally.
 
I'm no heating/cooling engineer, but to me, the o-ring concept at the inlet/outlet water tubes looks like a design flaw. Hose clamps are one thing, but those o-rings look like a weak link in the design process. I'm sure they had a reason at the time for doing it that way but we know what happens when o-rings fail.
 
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The O-Rings actually work pretty decent. Make sure they are fitted properly, and lube them before inserting the pipes. Also, make sure the screws holding the pipes to the box are tight, keeping the joint from moving. I believe will Glen Ray provide a couple of new O-Rings when they restore your heater core. If you buy the box restoration kit from Detroit Muscle Tech he also supplies the O-Rings and some lube. I ended up using the DMT O-rings on mine, I thought they fit better.
 
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