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ray_mcavoy · 10-17-2010, 06:46 PM

Hi vtwinsport,

No, that heater operation isn't normal due to your house routing.

Hot coolant is supposed to flow out of the intake manifold, through the 5/8" hose, and into the heater core. The outlet/return of the heater (3/4" hose) is hooked to one of two locations. Most trucks have it hooking into the radiator. While cars often had it hooked into that fitting on the top of the water pump.

So basically, what you've done is hooked your heater core between the two places that are normally used as returns for the heater core outlet.

It looks like your intake manifold has a boss (between the thermostat housing and the heater hose outlet) that could be drilled & tapped to accept your fan temp switch.

Another option might be to get one of those spacer blocks that mounts between the intake & thermostat housing. They're often used to plumb coolant lines from the back corners of the intake. You could use one of the holes in the spacer for your fan temp switch. And since it would be below the thermostat, it'd be reading engine coolant temp regardless of the thermostat being open or closed.

10-17-2010, 06:46 PM	#2
ray_mcavoy Registered User Join Date: Nov 2009 Location: Sherman, ME Posts: 2,373	Re: Heater hose routing Hi vtwinsport, No, that heater operation isn't normal due to your house routing. Hot coolant is supposed to flow out of the intake manifold, through the 5/8" hose, and into the heater core. The outlet/return of the heater (3/4" hose) is hooked to one of two locations. Most trucks have it hooking into the radiator. While cars often had it hooked into that fitting on the top of the water pump. So basically, what you've done is hooked your heater core between the two places that are normally used as returns for the heater core outlet. It looks like your intake manifold has a boss (between the thermostat housing and the heater hose outlet) that could be drilled & tapped to accept your fan temp switch. Another option might be to get one of those spacer blocks that mounts between the intake & thermostat housing. They're often used to plumb coolant lines from the back corners of the intake. You could use one of the holes in the spacer for your fan temp switch. And since it would be below the thermostat, it'd be reading engine coolant temp regardless of the thermostat being open or closed. Last edited by ray_mcavoy; 10-17-2010 at 06:48 PM.