Antifreeze Leaking From Under Dash Passenger Side

[RoadRunner1970]

Took the Roadrunner out this week for a long drive and noticed antifreeze leaking under the passenger side and collecting on the floor mat. Would this most likely be the heater box? It is still original so I am sure it needs restored. Does anyone have any pics of what's involved and also how hard it is to remove from a 70 B Body without air....Is there anyone on this site that restores them? Thanks in advance for your time....Brian

 

[dodgeboy440]

Took the Roadrunner out this week for a long drive and noticed antifreeze leaking under the passenger side and collecting on the floor mat. Would this most likely be the heater box? It is still original so I am sure it needs restored. Does anyone have any pics of what's involved and also how hard it is to remove from a 70 B Body without air....Is there anyone on this site that restores them? Thanks in advance for your time....Brian

Hey brother…. That’s gotta be your heater core !!
That’s a big pain in the posterior….
Getterdunnnnnn before it leaves you
Stranded……
You should be able to buy new replacement..
Good luck !
Mopar2ya!!

 

[dfrazz]

Heater core for sure. Not too difficult to remove entire box and replace heater core inside. I would recommend the brass heater core from Rock Auto.

 

[eldubb440]

you can bypass the heater core for now so you can still drive the car

 

[Green72]

If you do it yourself, make sure you also get a new gasket set the old ones will fall apart into dust! It's a really straight forward project not difficult.
https://www.classicindustries.com/product/1970/dodge/coronet/parts/mb1680.html,

 

[RR Fan Dan]

It’s the heater core. You can bypass by disconnecting the coolant lines from the core and jumping them together. Rock Auto has cores. Detroit muscle has gaskets. Rock auto 5% discount code

MOPAR - Heater Box Rebuild Gasket Sets - B Body 66-70 Heater Box - Detroit Muscle Technologies, LLC

More Information for FOUR SEASONS 90500

 

[pnora]

Took the Roadrunner out this week for a long drive and noticed antifreeze leaking under the passenger side and collecting on the floor mat. Would this most likely be the heater box? It is still original so I am sure it needs restored. Does anyone have any pics of what's involved and also how hard it is to remove from a 70 B Body without air....Is there anyone on this site that restores them? Thanks in advance for your time....Brian

As said most likely the heater core. But do not overlook the basic items. Heater hose clamps. Normally if there is a sealing problem it will be under the hood. However I have seen them show up inside. If the hose is pushed tight to the firewall it can create a seal and allow the coolant to weep to the inside. Rare but can it happen. Just double check them before pulling the box out.

 

[gkent]

Getting the heater out is no big deal ... three nuts on the firewall and one nut under the dash. Disconnet cables and hoses. Getting it back in ... A whole other story !! That will having your cursing and swearing.

Depending on your age and physical condition you might want to consider taking the front seat out first.

Before you take it out, measure from the bottom of the front of the heater box to the floor of the car and cut yourself a couple blocks of 2x4 about 1/2" and 1" shorter. These'll come en handy wrestling it back in.

Of the two shown, get the "mega" kit.

 

[RoadRunner1970]

I did notice steam coming from the cowl vent after driving it also....

 

[pnora]

I did notice steam coming from the cowl vent after driving it also....

Ok, now go out there and pinpoint the area and get to work fixing it.

 

[terrywalker]

I had the same thing happen in my 71 Challenger last year. At 73 years old, I removed the bucket seats, 4 speed shifter and glove box insert to make it easier to get to cables, etc. and to lower entire heater box out. I had the gasket set from DMT and fit a brass heater core from Autozone($60). Then things seemed to snowball from there. I decided the carpet needed replacing. Pulled out rear seat and interior panels and door sill plates. I then decided body paint on the floors could be touched up. At that point, I decided enough was enough and fixed everything, put in new carpet and put it back together. It took me almost 2 months as I repaired more and more. Be prepared. My simple heater core replacement snowballed but it looks and works great. LOL.
Terry W.

 

[CHGRSE74]

I would recommend having your heater core reconditioned locally at a rad shop if you can… I had to replace mine and I got a core from classic industry’s, price was ok but the tubes were not soldered to the reinforcing bracket properly and I could not assemble the heater box. I had to remove and reposition and resolder the bracket. Talking to other folks this is a common problem from offshore parts…nothing like the original parts.

 

[terrywalker]

I would recommend having your heater core reconditioned locally at a rad shop if you can… I had to replace mine and I got a core from classic industry’s, price was ok but the tubes were not soldered to the reinforcing bracket properly and I could not assemble the heater box. I had to remove and reposition and resolder the bracket. Talking to other folks this is a common problem from offshore parts…nothing like the original parts.

View attachment 2007404

That is true. When I got the Autozone brass heater core, I had to resolder the brackets on the inlet/ outlet tubes to get it to properly seat in the heater box. I also had to trim some of the bracket sheet metal with metal snips to get it to fit. Took me about 20 minutes..
Terry W.

 

[gkent]

I had the same thing happen in my 71 Challenger last year. At 73 years old, I removed the bucket seats, 4 speed shifter and glove box insert to make it easier to get to cables, etc. and to lower entire heater box out.

You don't need to go to that extreme with a 70 B body. The glove box liner is an absolute bitch to get in and out and will cause more grief than the heater box ! Shifter is not in the way at all.

 

[VANDAN]

You could pull the original, and try out the "New" Glen-ray option, which is Opening in Missouri I believe ? We'd All like to hear about their Service, and Quality...

 

[SgtSuperbird]

I 100% agree with CHGRSE24 and Terry W.: I just rebuilt a '71 A/C heater box and replaced the heater core. The heater core, unknown brand (Made in Mexico), did not even closely fit. I had to unsolder and reposition the tube bracket (super easy), and trim and bend the flanges, so it nested into the box properly.

Don't be afraid to do the box. (Or find the leak.) It's fairly easy to remove. Take pictures. Get a seal kit. Clean everything and reassemble. You'll be happy with the outcome.

 

[Some Car Guy]

Get the gaskets from Detroit. Well worth it.

 

[turbine68rt]

As said most likely the heater core. But do not overlook the basic items. Heater hose clamps. Normally if there is a sealing problem it will be under the hood. However I have seen them show up inside. If the hose is pushed tight to the firewall it can create a seal and allow the coolant to weep to the inside. Rare but can it happen. Just double check them before pulling the box out.

Exactly. I had the exact same scenario using the factory spring clamps for restoration purposes and had coolant get past the firewall and onto the carpet. I used crimp clamps behind the spring clamps. Undetectable and no more leaks.