I have heard several people say in different places its possible to replace the heater core without pulling the dash through the glove compartment. Has anyone done this or can think of a way it would be possible? I was thinking of cuting the box of where you can see it in the dash. Any advice?
I pull dashes as part of my job. That's a BMW X5 dash removed for a passenger airbag replacement.
Here's some tips:
1. Get a manual. Haynes, Chilton, Clymer, Ford, it doesn't matter. Having step-by-step directions helps a ton.
2. Take pictures. Smartphones are wonderful things. As you take things apart, take pictures. It gives you a reference for reassembly.
3. Stay organized. Magnetic trays, ziplock bags, masking tape and a sharpie... These are all your friends.
4. If it doesn't come out easily, double-check your work. If it's hanging up on something, don't keep trying to jerk it loose. Use a mirror, a flashlight, an inspection camera, whatever you have at your disposal to see what's going on.
5. If possible, have a helper. Dashes are wide and bulky, having someone on each side makes it much easier.
On a non A/C car the heater core box has a door you can slide the core out of. Your car doesn't have that door. It had factory A/C at one time. The LMR picture on the right is an EFI setup. Google 1985 Mustang GT engine bay pictures and you'll see how it is supposed to look. The A/C lines are routed different on carbureted cars.
I thought I would suggest testing your new one before you install it. Doing this once is bad enough but it would suck to do it twice. You can submerge it in a bucket of water and plug one end while adding a small amount of air pressure to the other. As long as you don't see any bubbles you're good. I was told lung power is good enough and it has worked for me or I've been lucky. It's not a fun job but it's not as bad as you think. Good luck. Oh and be careful putting the hoses back on. You can ruin the new core if you're too aggressive.