yelo80vette

Thinking my heater core replacement project in my 1980 was going to be much harder than it ended up being, I began by cutting off the old hoses from the old
heater core without noting which hose went to where. Now, having finished the project (other than this part), I don't know which of the two hoses goes to where?
One hose comes from the engine block near the water pump and the other goes into an aluminum tube hear the AC compressor, then down to the heater control
valve. From there, I'm confused. Any illustration I can find doesn't really show. On my new heater core, one tube comes down on the passenger side and the other on
the drivers side. Maybe my little illustration can make my dilemma clear. Anybody? Suggestions? (help!!!)

Bikespace

The hoses, and the ports on the heater core, should be two different sizes. The 5/8" hose, I believe, is the outlet from the intake manifold, and the 3/4" hose is the return to the water pump (the "aluminum", but possibly steel, return hose that plugs into the water pump). I'd expect the water shut-off valve to be on the outlet (5/8") side. If the heater core has two inlets the same size, the shut-off valve must make a size transition.

I tossed all of my stock heater components from my 80, so I can't measure anything, but the routing should be in the AIM or Shop Manual. I'll post a photo if I can find mine...

yelo80vette

Excellent. I'll check that out. Thanks.

Bikespace

Here you go. Not the clearest picture, but the heater core hoses are clearly different sizes.

You can pick up a Factory Assembly Manual and Shop Manual from any of the vendors, and even Rock Auto. They are worth their weight in gold!

yelo80vette

I have this picture but only now do I see that I was looking at it wrong. I think this'll do it. Thanks again.