Bypass heater core questions

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73mach1whiskey

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My Car
1973 Mach1 Ram Air 351C
So i must have destroyed my heater core taking out my ac. i know i had a heck of a time getting the evaporator valve out and probably broke something. not probably cause i did since it is pouring coolant. I will eventually replace the core but i don't have time right now and just want to drive the car. I know from reading on here it can be bypassed but have some questions to make sure i do it correctly.

I couldn't tell from looking at the hoses but are the pump and intake hoses the same size? If so then it will be ok to just take generic heater hose and run it in between forming a U-shape right? 1973 351C 4v

Also I have a valve, or something like a valve in between the two hoses with vacuum lines attached near the pump. Can i just remove that and plug up the vacuum ports? Also on one of the hoses near the firewall there is another valve with some sort of vacuum attached. Would it be ok to remove that as well and just plug that one? Thanks!

The first pic is the valve near the water pump and intake manifold.

The second pic is the valve near the firewall below the air cleaner.

I'm sure you all know that already :)

2015-08-26 06.53.39b.jpg

2015-08-26 06.59.35b.jpg

 
Last edited by a moderator:
yes the hoses are the same diameter and just making a U will bypass the heater core.

the valve is the heater control valve it pinches off the heater core when you want cool air or air conditioned air to flow through the heater box without being heated, basically that valve is a heater core bypass in of itself.

that valve is very rotted out from the look of it and needs to be replaced anyway.

now when you disconnect that valve make sure to cap the vaccum hose or you will have a vacuum leak through the A/C system.

 
Just go to your hardware store and get a barbed connector that fits the heater hose so that the hose doesn't blow off and like you have been told just loop the hoses.

A word of caution when you do change the core. Do a air pressure test on the new core before installing. Over the years I have had two that had leaks when new and did not test one so got it all back together and it leaked, bummer. The last one was just recently a new core for a 73 and it had a leak inside the coring not at the tube so it could not be repaired. They took it back and the next one tested ok. I only use 15 lbs. of air similar to pressure in the system.

Watch some videos on how to change so you don't damage your heater box, good winter project.

David

 
Sounds good! Thanks guys and yeah i figured that valve wouldn't be working anyways considering the condition. Also great tip on the air pressure test! I have not done one yet but from reading what a pita it is, it would suck to have to do it all over again!

 
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