Author Topic: '79 heater hoses  (Read 8231 times)

Offline 79Squared

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'79 heater hoses
« on: July 19, 2015, 03:48:41 PM »
So, looking all over and cant find anything specific to 73-80 heater hose routing. Opinions are also all over the place.
My heater box inside the cab under the dash (measured 125) gets so hot that the inside of my truck is almost unbearable in hot weather. And yes I have checked and my motor does not run hotter than it should. About 200 on the block and 180 at the heads.
So a couple of questions here.
1.Which connection at the heater core (top and bottom) is in and which one is out? And where should they be connected? (intake, radiator, water pump)
2.Can I just plugging both the passages at the intake and water pump? Will this mess with the flow of the motor? As I dont need a heater at all because its a fair weather truck anyways. And no my ac is not connected and wont be.

Offline Don5

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Re: '79 heater hoses
« Reply #1 on: July 19, 2015, 04:08:29 PM »
On my 79 the top hose is hooked up to the water pump and the bottom hose is hooked into the intake. The top hose is the in side. I don't think it will hurt the engine to put a plug in the water pump and a plug in the intake as well. I have never done it since I have to have a good heater here in WV. Someone that has done it can weigh in here if they want. 
It's been a LONG time since I have been called a newbie. Just sayin....

1979 GMC K15 355, SM 465, 205, 3.73 Dana 44 with a Spartan Locker, 12 bolt Eaton limited slip and 6 inch lift with 36 x 12.50 Super Swamper TSL's.

Offline Jason S

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Re: '79 heater hoses
« Reply #2 on: July 19, 2015, 04:28:41 PM »
The hose on the intake manifold connection is supply to the heater core, the return hose from the heater core can be plumbed to the water pump or to the radiator. 

I've placed a ball-valve shut off inline on the heater supply hose (hose connected to intake) on both of my trucks to try to keep added heat out of the cab in the summer.  When outside temperatures start to cool off, I can open  the valve and return the heater to normal operation.

When the valve is off there won't be coolant running through the core and it's possible that some corrosion could build in the core.  Keeping the extra heat out of the cab in summer is more important to me.
1973 GMC K2500, Super Custom, Camper Special, 350, TH350, NP203, 4.10's
1974 Chevrolet K10, Custom Deluxe, 350, SM465, NP203, 3.73's

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Offline 79Squared

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Re: '79 heater hoses
« Reply #3 on: July 19, 2015, 04:53:27 PM »
Ok so really I could just plug off the manifold passage and want hurt the water flow of the motor? I would just go that rout if it doesnt hurt anything.

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Offline Jason S

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Re: '79 heater hoses
« Reply #4 on: July 19, 2015, 05:08:32 PM »
There shouldn't be any issues as long as your cooling system is in good shape.

Remove the heater hose fittings on the intake and water pump (or radiator) and plug with brass plugs.  Apply teflon tape or teflon sealer to the plug threads. 
1973 GMC K2500, Super Custom, Camper Special, 350, TH350, NP203, 4.10's
1974 Chevrolet K10, Custom Deluxe, 350, SM465, NP203, 3.73's

"1) Peace through strength; 2) Trust but verify; 3) Beware of evil in the modern world"

Offline 79Squared

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Re: '79 heater hoses
« Reply #5 on: July 19, 2015, 05:13:58 PM »
Cool I think that's my way. Get the hoses out all together haha

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Offline enaberif

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Re: '79 heater hoses
« Reply #6 on: July 19, 2015, 07:13:25 PM »
Ok so really I could just plug off the manifold passage and want hurt the water flow of the motor? I would just go that rout if it doesnt hurt anything.

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Water pump has a built in bypass in case a hose or something gets blocked. Its why its ok to do this.

Offline 79Squared

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Re: '79 heater hoses
« Reply #7 on: July 19, 2015, 07:14:38 PM »
Thank you.

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Offline Irish_Alley

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Re: '79 heater hoses
« Reply #8 on: August 02, 2015, 08:48:09 AM »
when i worked at autozone i never understood why ford had a heater control valve. but it makes perfect sense


you can either apply vacuum to use the bypass or you can remove the vacuum solenoid and operate it like on on off switch   
part number 74809 or 5954
you can find them on many fords but one is a 96 aerostar

if you do it this way you will keep coolant in the heater core and the water pump can still utilize the hose thats hooked up
think the hose ends are 5/8"
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