Heater core leaking ? ?

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6DUB606

Well-known member
Joined
Apr 12, 2018
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116
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Location
Australia
My Car
'73 Mach 1 with checkered history. Working on repairing
what has to be done, replacing what I can to make a nice car and living with the rest. Being on the other side of the world presents challenges but we will get there.
I feel some bad news coming - there is a trace of green antifreeze mixed in with condensate dripping under the car after A / C running.  Does this suggest the heater core is leaking and draining into the housing box cavity ?  The coolant level has dropped a bit too.

No sign of leaks under the hood at heater hose connections and it is back where the drain line comes out.  I see a couple of good threads covering removal of the entire heater & A C system but any better ideas before I go further.

All good fun. :huh: 

PKJ

 
If it is coming out with the condensating water from the heater box I would say so. Unfortunately I cannot think of any other way to check. If your coolant level is dropping and that's the only place you see coolant, then it's probably heater core. Maybe check the passenger side floor for wetness as well. BIG project. Good Luck!!

 
none of these cores are an easy fix if leaking...PITA.. but lets say u really don't need it, then by pay it. run a single hose from port to port on engine. but the core does help in engine cooling.

 
The heater core is a pain for sure especially with AC. I am doing mine right now. I go to Advance Auto to pick up the core. I have used in past and they have 3 year warranty.

It is probably the worst job on the whole car but anyone can do it. You do have to take the dash loose and move it back to get the heater box out.

Be sure and take the drain hose off before you do anything else. It is also much easier if you remove both seats.

If you do not take the whole dash out there are a few wires that are a real pain to get out. The center part of the heater box is where the blower is and there are connectors to it and a ground wire screwed to the cowl.

It is a good time to review condition of the cowl also. With the box out you can use mirror and look into the cowl from the opening to the heater. I reach up through the hole and use a paint brush to apply POR after I clean as best I can then apply body sealer. It is guaranteed there is a leak there almost always. Look for any mice nests in the cowl also on both sides. The AC car does not have an opening on the driver side but mice love to build there.

You will also need a foam kit to replace all the foam in the heater box on the doors and seals. Go to the West Coast Cougar site and watch video on how to repair. You also might need to order the foam seal the goes around the heater core and AC tubes going through the firewall. Don or any Mustang supply usually has them.

There are two vacuum motors on the box that you need to test with a vacuum pump.

Also when you get your new heater core do air test it under water with about 15 lbs. of pressure. I have had two bad out of the box in past and one was NOS Ford.

I always add the 1/4" wire mesh between the foam seal at the cowl.

There are not that many fasteners holding the dash but if you remove the whole dash you have to unplug all the wire harness which takes time and is a pain.

I have a two post lift and do most of the removal with the car on the lift raised so I stand beside the car instead of having to lay in the floor.

Either pull your carpet out or protect with plastic the smell of antifreeze never seems to go away.

So I am off to get my heater core in a bit.

If you have not already change the AC over to new refrigerant good time to do also. Replace the dryer filter and change the lube in the compressor and of course the new green O-rings.

I am having to do the brake booster so I am burnt out on the tough Mustang repairs.

Some pics of past one I did.

It is not a job you do in one weekend usually. You have lots of cleaning to do and if your case looks bad you can clean and spray with satin clear to make it look new again.

The foam kits look nothing like the original much less dense but all you can get. Can clean all the ducts and blower housing makes air smell better.











upload photos online

 
The heater core is a pain for sure especially with AC. I am doing mine right now. I go to Advance Auto to pick up the core. I have used in past and they have 3 year warranty.

It is probably the worst job on the whole car but anyone can do it. You do have to take the dash loose and move it back to get the heater box out.

Be sure and take the drain hose off before you do anything else. It is also much easier if you remove both seats.

If you do not take the whole dash out there are a few wires that are a real pain to get out. The center part of the heater box is where the blower is and there are connectors to it and a ground wire screwed to the cowl.

It is a good time to review condition of the cowl also. With the box out you can use mirror and look into the cowl from the opening to the heater. I reach up through the hole and use a paint brush to apply POR after I clean as best I can then apply body sealer. It is guaranteed there is a leak there almost always. Look for any mice nests in the cowl also on both sides. The AC car does not have an opening on the driver side but mice love to build there.

You will also need a foam kit to replace all the foam in the heater box on the doors and seals. Go to the West Coast Cougar site and watch video on how to repair. You also might need to order the foam seal the goes around the heater core and AC tubes going through the firewall. Don or any Mustang supply usually has them.

There are two vacuum motors on the box that you need to test with a vacuum pump.

Also when you get your new heater core do air test it under water with about 15 lbs. of pressure. I have had two bad out of the box in past and one was NOS Ford.

I always add the 1/4" wire mesh between the foam seal at the cowl.

There are not that many fasteners holding the dash but if you remove the whole dash you have to unplug all the wire harness which takes time and is a pain.

I have a two post lift and do most of the removal with the car on the lift raised so I stand beside the car instead of having to lay in the floor.

Either pull your carpet out or protect with plastic the smell of antifreeze never seems to go away.

So I am off to get my heater core in a bit.

If you have not already change the AC over to new refrigerant good time to do also. Replace the dryer filter and change the lube in the compressor and of course the new green O-rings.

I am having to do the brake booster so I am burnt out on the tough Mustang repairs.

Some pics of past one I did.

It is not a job you do in one weekend usually. You have lots of cleaning to do and if your case looks bad you can clean and spray with satin clear to make it look new again.

The foam kits look nothing like the original much less dense but all you can get. Can clean all the ducts and blower housing makes air smell better.











upload photos online
Yup - that's what I was scared of !  In the short term I will bypass & join the two hoses back near the firewall so generally out of sight.  Understand that it may impact cooling to some extent but so be it.  No coolant showing on the floor ( yet ! ) so this will avoid potential if it totally fails.

Thanks for your advice too David - I've already put fly screen mesh under the cowl vents to stop leaves & rubbish getting it there.  

Thanks troops - a job for another day.

PKJ

 
We could not figure why the passenger carpet was wet sometimes, I should say damp.

It was raining a lot at the time so we thought maybe a leak. Noticed the radiator was

going down but not that much over a period of time. We had a pin hole leak in the

heater core.

mike

 
I feel some bad news coming - there is a trace of green antifreeze mixed in with condensate dripping under the car after A / C running.  Does this suggest the heater core is leaking and draining into the housing box cavity ?  The coolant level has dropped a bit too.

No sign of leaks under the hood at heater hose connections and it is back where the drain line comes out.  I see a couple of good threads covering removal of the entire heater & A C system but any better ideas before I go further.

All good fun. :huh: 

PKJ
As others have said it a real pain to change out. If you don't use the heater, you have options. One LONG hose from the engine in one hole on the firewall back out the other hole in the firewall and back to the engine, no more heater core failures. I recently had a heater core failure on my 69 Cougar. I replaced the core but 100 % blocked any coolant from flowing through heater core. I bought two 5/8" heater hose unions, epoxied two rivet nuts into the unions, then screwed in two stainless steel set screws with sealant on them. Inserted the unions in the hoses with the allen head side of the set screws facing the front of the engine. This way if for whatever reason I want to enable the heater again, I can just remove the set screws. I haven't used the heater in the Cougar since 1985 and I don't want to ever do this job again. Chuck

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OK, here is the cheapest, easiest, craziest way to fix a slow leak.  You will NOT believe me as i made the mistake of NOT believing my mother when she told me about this,  Yes, my MOTHER told me of this trick.

Get a teaspoon of Ginger(yes the spice, Ginger,  In powder form, all you need is a teaspoon full)  Drop it in your radiator fill opening and run your engine and heater system to make sure everything circulates.  You do this with a normal coolant mix of antifreeze and water.  Nothing out of the ordinary.

That's it.  You are done.

I DID NOT believe it either.  In High School I had a leaking radiator on my Mach.  I tried to think of how to fix the problem as my coolant kept going down.  My mother said to try the Ginger and I did not believe her.  So she comes out with some ginger and drops it in the radiator.  It never leaked again.  That was around 1985,  I tore the car down in about 1998 to begin restoration and that radiator never did leak again.

So before you pull the dash, divert the hoses, or do anything else I would try this.  It worked on mine.

kcmash

Yep, go ahead and Google it too.

 
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