Heater core leaking...replace or by-pass?

[1973stang]

I found 3 leaks in my cooling system

1) Water pump ( I am replacing w/Milodon #697 16235)

2) Heater core valve (any reco)

3) Heater core itself

THe coolant is dripping out of the A/C condensation pipe.

I live in Los Angeles...so heater requirement is not critical.

I have A/C in the car.

And I read it is painful and expensive (labor) to replace heater core in A/C car.

Can I just BY-PASS the heater core and save the monies ???? WIll it affect the A/C performance ???

Rush

 

[Mikes73]

Just get some heater hose and loop it at the water pump. I'm in the same boat as you and will change out mine eventually.

 

[72HCODE]

yes if you don't need the heater core and it is leaking doing the loop bypass is fine.

If you wanted to change the heater core with a working A/C system it will require draining the A/C system of freon.

then you will need to remove the AC lines and the expansion valve before you even get to point of being able to take apart the inside of the car to get the heater box out.

from there you will need to disassemble the A/C heater box as the heater core is buried at the bottem of the box.

you will discover all kinds of problems along the way.

when you go to put everything back together. you can run into major sealing issues with the A/C lines that may require new expansion valve to compressor lines and it would be a good idea to replace the A/C dryer/filter.

What happens is the original hoses expand under the charge pressure of the freon. once the system depressurizes the hoses can change shape again and then they never seal correctly at the O rings. i had that happen on one car that needed a new A/C compressor, changed the compressor and then the system leaked at every other O ring joint requiring A/C hose replacement.

the cost can be upwards of 1000$ just on the A/C system.

the cost of just servicing the A/C system with new freon is about 150-200$ the cost of the hoses if needed and a dryer will also be around 200$. when you bring the car in to have the freon removed that can cost 100-150$ unless you want to help the ozone layer .

now if your system is R-12 that can be a major headache. you will want to avoid changing to R-134a because then your taking about a new condenser core rated for 134, and having the entire system completely flushed to change to 134a mineral oil.

or you have to find a place licensed for R-12 and the cost can be higher dealing with that aspect.

before you know it you might have to spend 1500-2000$ to have the heater core and the A/c system working again. in addition to a ton of labor that you would want to do yourself or get hammered for another 1000$

now i would say if the heater core was leaking and the A/C was non-functional then it would be worth going down the road and replacing everything to start over.

but since the A/C is working leave it alone. loop the bypass to the water pump.

then what i would do is remove the heater lines going to the firewall.

cap off the heater core from the firewall.

pull the Heater control valve in the engine bay and make sure you cap off the vacuum line that went to the heater control valve to prevent a vacuum leak.

the a/c system will work the same and when you switch to heat it will work as normal just not produce any heat for the interior cabin.

stockpile new parts for the feature and then if you keep the car plan on what i talked about at the start.

 

[Widowmaker00]

I changed my heater core and it wasn't that hard, took a weekend. A few years later one of the heater hoses started leaking so I just bypassed it. Problem was when I looped the hose the car started overheating, I ended up just plugging the heater hose connections and it stopped overheating.

 

[matrixx]

This makes me somewhat feel better about not having A/C. Wow that's a lot of work. My only concern is if you ever start to see rising engine temps I could turn the heat on and it help cool it down like a miniature radiator. At least my 289 in my 65 worked like that.

In your boat, bypass all the way.

 

[1973stang]

Can't u get to it from the dashboard side???

 

[72HCODE]

non-ac cars are VERY easy to work on compared to the A/C cars. the heater box in the a/c cars is extremely complex.

to correctly work on the A/C box you are suppose to remove the entire dashboard. The work can be done with the dashboard in place however it is the worst game of tetris you have ever played and you can break the fiberglass box very easily.

that is just dealing with the box itself.

as for the core buried inside the box, it will not just pop out the bottom there are brackets with bolts on both sides that you cannot access from the firewall side. in addition there are foam pieces that need to be transferred from the old core to the new core and it will require some custom fitting to make a repop core sit correctly in the box.

take a look here for an idea of what is in store

http://s1031.photobucket.com/user/72hcode/library/Heater%20Box%20AC?sort=2&page=1

it is very involved. Just getting the box out of the car is a ton of work as well.

this is why any car that has had a heater core replaced in the past will have a VERY broken heater, AC box basically 24 hours into the job your kicking it into the car with your steel toe boots from the utter frustration.

 

[tommy]

so why would it overheat with a bypass loop?

 

[1973stang]

Tommy,

I was wondering the same

72HCODE

Why not replace the whole heater box..e.g from CJ pony parts (for A/C car)

http://www.cjponyparts.com/heater-box-assembly-with-air-conditioning-1971-1973/p/HBA6/

so why would it overheat with a bypass loop?

 

[72HCODE]

the reason the car would overheat is because the radiator itself needs to be replaced, the heater core acts as a secondary cooling system.

remember back when your sitting in traffic and dad would suddenly roll the windows down, turn on the heater and not say a word?

that is because the car was overheating and the heater core would act as a secondary cooling radiator.

basically replace the radiator with a 3 row or new repop or a new core with high efficiency veins cause the old one is most likely full of sludge and clogged up.

there are many systems that compensate for overheating most guys rip them off and think they are evil emissions devices.

but when you loop the water pump and the car is overheating you need a new radiator, i wouldn't even flush it at that point i would have it re-cored at least boiling it would be worthless .

----------

72HCODE

Why not replace the whole heater box..e.g from CJ pony parts (for A/C car)

http://www.cjponyparts.com/heater-box-as...73/p/HBA6/

------------

you realize that is just a new Case for the heater box, you would need to transfer all the internals into the new box it is not ready to bolt in.

also these did not exist 5 years ago so you had to source them from donor cars.

also the repops are garbage i would want an original box which you can still find but need to be restored.

 

[1973stang]

72HCODE

Widomaker00 wrote

"I ended up just plugging the heater hose connections and it stopped overheating"

So this is would not be the case of BAD RADIATOR. ???

the reason the car would overheat is because the radiator itself needs to be replaced, the heater core acts as a secondary cooling system.

remember back when your sitting in traffic and dad would suddenly roll the windows down, turn on the heater and not say a word?

that is because the car was overheating and the heater core would act as a secondary cooling radiator.

basically replace the radiator with a 3 row or new repop or a new core with high efficiency veins cause the old one is most likely full of sludge and clogged up.

there are many systems that compensate for overheating most guys rip them off and think they are evil emissions devices.

but when you loop the water pump and the car is overheating you need a new radiator, i wouldn't even flush it at that point i would have it re-cored at least boiling it would be worthless .

----------

72HCODE

Why not replace the whole heater box..e.g from CJ pony parts (for A/C car)

http://www.cjponyparts.com/heater-box-as...73/p/HBA6/

------------

you realize that is just a new Case for the heater box, you would need to transfer all the internals into the new box it is not ready to bolt in.

also these did not exist 5 years ago so you had to source them from donor cars.

also the repops are garbage i would want an original box which you can still find but need to be restored.

 

[Wolverine]

1. You can bypass the heater core as a SHORT TERM fix. Think about fixing your dog. Which is better for him/you in the long run. Fixing him or keeping him chained up in the backyard.

2. However, the heater core is part of the cooling system, believe it or not. Basically, the heater core is a small radiator in a housing, and as air passes through it, the water temperature decreases slightly. That is why if your car is over heating it helps to TURN ON THE HEATER to blow more air past the heat core/small radiator housing.

3. Whatever you do, DO NOT put any of that RADIATOR FIX LEAK into your radiator.

4. For help, I am pretty sure there is at least 1 video of changing out the heater core with the AC option. Probably done by Q. The replacement IS A PAIN. BUT, not changing out the heater core on your Mustang is like going to the prom with Pam Anderson and not making it to second base. Not only will you regret not getting to second...you'll regret getting not getting to home...and EVERYONE is going to know you didn't make it to 2nd.

In fact, I propose a new HEATER CORE symbol for those of us who have braved the inner annals of our automobiles and actually manned up to change the God forsaken heater core.

 

[72HCODE]

Or bad water pump or bad thermostat or missing bypass plate under the thermostat.

Usually you loop the water pump and the car starts overheating, lot of guys leave the coolant control valve disconnected to the heater core is always on even if the fan is off.

You can inspect the condition of the coolant too if its brown you have problems.

72HCODE

Widomaker00 wrote

"I ended up just plugging the heater hose connections and it stopped overheating"

So this is would not be the case of BAD RADIATOR. ???

the reason the car would overheat is because the radiator itself needs to be replaced, the heater core acts as a secondary cooling system.

remember back when your sitting in traffic and dad would suddenly roll the windows down, turn on the heater and not say a word?

that is because the car was overheating and the heater core would act as a secondary cooling radiator.

basically replace the radiator with a 3 row or new repop or a new core with high efficiency veins cause the old one is most likely full of sludge and clogged up.

there are many systems that compensate for overheating most guys rip them off and think they are evil emissions devices.

but when you loop the water pump and the car is overheating you need a new radiator, i wouldn't even flush it at that point i would have it re-cored at least boiling it would be worthless .

----------

72HCODE

Why not replace the whole heater box..e.g from CJ pony parts (for A/C car)

http://www.cjponyparts.com/heater-box-as...73/p/HBA6/

------------

you realize that is just a new Case for the heater box, you would need to transfer all the internals into the new box it is not ready to bolt in.

also these did not exist 5 years ago so you had to source them from donor cars.

also the repops are garbage i would want an original box which you can still find but need to be restored.

 

[droptop73]

the reason the car would overheat is because the radiator itself needs to be replaced, the heater core acts as a secondary cooling system.

remember back when your sitting in traffic and dad would suddenly roll the windows down, turn on the heater and not say a word?

that is because the car was overheating and the heater core would act as a secondary cooling radiator.

basically replace the radiator with a 3 row or new repop or a new core with high efficiency veins cause the old one is most likely full of sludge and clogged up.

there are many systems that compensate for overheating most guys rip them off and think they are evil emissions devices.

but when you loop the water pump and the car is overheating you need a new radiator, i wouldn't even flush it at that point i would have it re-cored at least boiling it would be worthless .

----------

72HCODE

Why not replace the whole heater box..e.g from CJ pony parts (for A/C car)

http://www.cjponyparts.com/heater-box-as...73/p/HBA6/

------------

you realize that is just a new Case for the heater box, you would need to transfer all the internals into the new box it is not ready to bolt in.

also these did not exist 5 years ago so you had to source them from donor cars.

also the repops are garbage i would want an original box which you can still find but need to be restored.

Bypassing the heater core is what Ford did on air conditioned cars to assure that the a/c cooled properly.

 

[Manu Mach1]

My heater core was leaking too. I removed it, by-passed, order a new one, and...........................................................

The new one is still in the box. I don't have any problems with overheating the engine, but here the temperature is not so high as some part in US.

The engine temperature reaches 85°C degrees celsius(185°F) .

I also do not understand why there is an additional electric fan attached to the front of the radiator.