Hello - new guy here.

I recently bought a 1972 Oldsmobile Cutlass Supreme with factory air conditioning. I was wondering why my glass kept fogging up and realised that I have a coolant leak in the front passenger footwell, near the top left corner of the footwell i.e. close to the transmission tunnel.

I was told it's common for heater cores to leak but that it could also just be a leak from a hose. Having an A/C car, I have a lot of stuff around the heater core area at the firewall.

I want to bypass the heater for the time being (btw warm air works great, I just have a leak) but also want to fix this in the near future. What do I need to look for? What do I need to disassemble? Does anyone have exploded diagrams or videos of how to take this apart? Are alloy heater core replacements any good from RockAuto?

As some additional information - even with the A/C controls set to OFF and COOL, the passenger side of the front windshield likes to fog up quite a bit around the area where the defog vent is. Carpet hasn't had a chance to dry completely either.

Issue number two is that I only appear to be getting air through the floor vents. Heard that's a vaccum issue? I have a hose going from the intake manifold to the black ball under the bonnet and there is another vaccum hose going from that ball into the car. Unsure if the hose is actually attached to where it needs to be though.

Many thanks - any help much appreciated.

Thanks,
Mikolaj

 

It's pretty involved job. The lower bolt on the firewall side requires you to pull the fender liner. I just removed a few bolts on the liner and spaced it out with a 2x4. You are working blind. You have to get the service manual to walk you through it. I also removed the glove box. Set a side a better part of a day.

Pat

 

If 100% unmodified isn’t important to you, you can carefully center punch and drill out the one inaccessible bolt from inside the car. That leaves the stud and nut in the outside heater case.

I have done this on really rusty cars, or vehicle’s that I didnt care about other than keeping it going.

Is it “right”? Nope. Will it hurt anything? Probably not. Your choice.

 

I have removed that one nut by pulling the lower edge of the fender liner away and getting a wrench on it. It was a PITA but I did not put it back on, figuring all the other ones were sufficient to hold the box onto the firewall. That came in handy when I had to replace the heater core 3 times over the next 40 years. It’s a much easier job when you don’t have to get to that one fastener.

 

I also found it easier to remove the front passenger seat, to get under and pull the case out, especially at my age now. Needed my wife to help me guide the case back in when I was putting it back together to help line up the studs to the holes in the firewall,

 

Welcome to the site.

 

Bypassing the whole deal is easy from the engine compartment if you are asking about that. Just remove the hose ends from the firewall and completely remove the one that connects to the back of the intake manifold near the distributor and connect the loose end from the other one in it's place. There you have it, water from the pump to the back of the engine, no heater core connected any longer.