Heater Hose Routing

[Jtobe81]

What is the correct heater hose routing from the engine to the heater core? water pump to core or intake to core.

 

[Rustisbest]

5/8" hose from the intake to the lower heater core inlet
3/4" out to the pump or the radiator

 

[Turbo4whl]

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[projo198]

I just did this, and it changes between models and transmissions.

My '78 K10 is a manual and stated smaller bottom heater hose (5/8 pushing coolant to the heater core) from the intake manifold and larger top return hose (3/4) straight back to the water pump.

I think it would work either way, but my own radiator does not have a port where the diagram above shows one.

Lastly you may consider a 5/8 ball valve for shutting off the flow during the summer to avoid excess cabin heat. You'll need to order one though, 5/8 is not a commonly used valve size found at hardware stores.

 

[tsgs84]

I just did this, and it changes between models and transmissions.

My '78 K10 is a manual and stated smaller bottom heater hose (5/8 pushing coolant to the heater core) from the intake manifold and larger top return hose (3/4) straight back to the water pump.

I think it would work either way, but my own radiator does not have a port where the diagram above shows one.

Lastly you may consider a 5/8 ball valve for shutting off the flow during the summer to avoid excess cabin heat. You'll need to order one though, 5/8 is not a commonly used valve size found at hardware stores.

 

[tsgs84]

Correct 3/4 hose goes to water pump or radiator not both, if your radiator doesn’t have a hose port then the hose goes to the water pump. This is mine.

 

[Logbed]

Hi, figuring out the same things. The one heater hose goes to the radiator top. I had the other heater hose go to the intake with the previous engine, but is it possible to put that hose to the pump top?

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[83Stepper]

Hi, figuring out the same things. The one heater hose goes to the radiator top. I had the other heater hose go to the intake with the previous engine, but is it possible to put that hose to the pump top?

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Nope it won't work with the hoses going from the water pump top and the radiator. Those are basically both return hoses and you'll never get any water pushing through the heater core like it should. Ask me how I know lol. The feed hose (5/8" hose from heater core) goes to the intake manifold. The return/suction hose (3/4" hose from heater core) goes to either the radiator or the top of the water pump. Heat won't work with both sides of the heater core hooked up to a return/suction line.

 

[Ricko1966]

I just did this, and it changes between models and transmissions.

My '78 K10 is a manual and stated smaller bottom heater hose (5/8 pushing coolant to the heater core) from the intake manifold and larger top return hose (3/4) straight back to the water pump.

I think it would work either way, but my own radiator does not have a port where the diagram above shows one.

Lastly you may consider a 5/8 ball valve for shutting off the flow during the summer to avoid excess cabin heat. You'll need to order one though, 5/8 is not a commonly used valve size found at hardware stores.

A ball valve in the heater hose is potentially a bad idea.Sometimes the heater core is also used as a coolant bypass. A ballvalve works fine for some intakes and blocks but others. And causes some cylinders to run hot in others. There's still a slick way of doing it cheap. Use a bypass heater valve. Super common,it allows water through the heater core in one position,but bypasses in the other position. I'll look one up for a 99 escalade they are 15 or 30 bucks

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