Heater Hose Locations?

[81GMCSierra1500]

Hey again,

My truck's heater hasn't been hooked up since I bought it, and I'm slowly tackling all these little issues before the full restoration begins next spring, and I'm just trying to hook up my heater, to see if there was any particular reason why it was unhooked... Where do the heater hoses run... i.e: the hose from intake manifold goes where, and the hose from the pump goes where (upper/lower port). Once that's done, I need to find out why I have water leaking from the top of the heater core housing (interior) into the cab and onto the floor. It;s not a major issue, it's more annoying than anything else, but does anybody have any thoughts on that? I'm wondering if it's a cowl seal or something, caused by rainwater leaking into the cowl, and through into the cab... Thoughts would be greatly appreciated, surely somebody out there has had this issue before...

Cheers guys,

'81

[geezer#99]

I thought you'd have that truck rebuilt by now Mike!!
On mine the hose from the intake goes to the outside lower port on the heater.
The outlet from the heater (top inside port) goes back to a nipple on my rad. My truck has ac. Non ac trucks the return hose goes to the water pump.
Your interior leak is likely the vent on the kick panel. The design of the vent catches water from the cowl. There's a gasket between the plastic vent housing and the body but they deteriorate and cause the leak.

[400/400]

Geezer#99 is correct on the routing. Also it's good to note that you'll need two separate hose diameters as well. The engine to heater core "pressure" side uses a smaller hose than the heater core to radiator "return" hose.

[Axle]

You'll need 5/8" heater hose and 3/4" heater hose. The nipples are sized accordingly. If I where you, I'd start by just hooking up the hoses to the heater core, filling it (heater) with a garden hose and seeing if you end up with water in the cab due to a leaking core. If possible, cap it and put pressure to it and let it sit.

Alex.

[White Longbed]

Thank you Geezer#99 and 400/400. My 1974 C10 longbed has heat all the time so last spring I just looped the heater core hose back to the heater core and the engine hose back to the engine. Now it's winter and I forgot which one goes where. You guys answered this question perfectly. So now I'll be able to drive my truck when I want.