This makes 0 sense to me! Heater hose route

[mtbadbob]

My 84 came with this setup, water pump is plugged off. Somebody told me it was the HD cooling option which makes sense as my truck came from Nevada. Hope this is helpful.

My '87 is like that only the connection is behind the TB and the Coolant Temp Sensor is where your hose connects to manifold. I'm assuming GM did that on the TBI's for a more accurate reading, the coolant having to travel further before it gets to the temp sensor.

 

[mtbadbob]

This has been the thought of being on the cold side till the thermostat opens. But does the connection on the intake not get flow till the thermostat is open anyway ?

Right, it won't flow until stat opens, but coolant is getting warmed sitting in the intake & engine before hand.

 

[jimmy78]

Right, it won't flow until stat opens, but coolant is getting warmed sitting in the intake & engine before hand. It's not really on the cold side as it flows back into the radiator from t-stat after it's hot enough to open it.

So in reality the difference from intake connection and water pump connection is a few minutes earlier hot coolant through the core. As it will be constantly flowing if connected to the water pump back into the rad till the rad sees warm coolant.

 

[Grit dog]

^Makes sense. Although I didn’t think twice about it. It’s how the truck was plumbed up when I got it.

 

[Turbo4whl]

This seems janky to say the least.

You are correct, your truck is not correct.

5/8" hose from the intake manifold to the heater core. 3/4" hose from heater core to the water pump, or the radiator, not both. This diagram @AuroraGirl posted is good, one or the other.

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[legopnuematic]

LOL "It ran when I parked it"

It took a light slumber from 1995-2018

 

[82sbshortbed]

I think everyone is making it more complicated than it is. Warm water flows through core with no leaks is good. Pump to core, core to radiator. Check for leaks. Good to go.

Or if your radiator doesn't have a spot for the heater hose(some don't)then it's pump to core, core to intake manifold. No leaks then good to go.

 

[89Suburban]

My 84 came with this setup, water pump is plugged off. Somebody told me it was the HD cooling option which makes sense as my truck came from Nevada. Hope this is helpful.

I like that adjuster on the alternator, pretty slick.

 

[DoubleDingo]

Can someone shed some light on this monstrosity of a heater hose routing.

Rad to heater core with tee to intake manifold

Heater core to water pump

This seems janky to say the least.

Maybe there was a valve to stop the flow in the summer months and it got removed?

 

[DoubleDingo]

For simplicity sake, larger hose has the warmer coolant to the core, the smaller hose is the cooler coolant coming out of the core to be reheated and cycled through the system.

But yeah, your setup needs to be fixed the way everyone has showed with diagrams and their setups.

 

[Turbo4whl]

I think everyone is making it more complicated than it is. Pump to core, core to radiator.

Or if your radiator doesn't have a spot for the heater hose(some don't)then it's pump to core, core to intake manifold

For simplicity sake, larger hose has the warmer coolant to the core, the smaller hose is the cooler coolant coming out of the core to be reheated ......

I was going to let this go, but I cannot. These statements are wrong.

I bought two square body trucks brand new. I have worked on many squares in the fleet.

Cooler coolant is sucked from the water pump from the bottom of the radiator and is pumped into the engine block low. Hot coolant leaves the intake manifold through the thermostat.

There is a 5/8" fitting on the intake manifold where the hottest coolant should flow to the lower 5/8" pipe of the heater core. You get hot coolant to the heater core even if the thermostat has not opened to let it flow to the upper radiator hose. The coolant leaves the 3/4" upper heater core pipe back to the water pump, or the radiator.

This is how the factory made them to get heat to the cab quickly. Naturally, the heater will still work either way, but it will work best how I have stated.

 

[DoubleDingo]

I was going to let this go, but I cannot. These statements are wrong.

I bought two square body trucks brand new. I have worked on many squares in the fleet.

Cooler coolant is sucked from the water pump from the bottom of the radiator and is pumped into the engine block low. Hot coolant leaves the intake manifold through the thermostat.

There is a 5/8" fitting on the intake manifold where the hottest coolant should flow to the lower 5/8" pipe of the heater core. You get hot coolant to the heater core even if the thermostat has not opened to let it flow to the upper radiator hose. The coolant leaves the 3/4" upper heater core pipe back to the water pump, or the radiator.

This is how the factory made them to get heat to the cab quickly. Naturally, the heater will still work either way, but it will work best how I have stated.

Thanks for clarifying. My bad for posting wrong info. To me it makes more sense, though, hot coolant in the bigger hose for more volume to the heater core, and the smaller hose allows for some back pressure to slow the flow and let the heater core disperse more heat into the cabin, and thus, the cooler coolant flows in the smaller hose. Good to know I was wrong.

 

[Octane]

Can someone shed some light on this monstrosity of a heater hose routing.

Rad to heater core with tee to intake manifold

Heater core to water pump

This seems janky to say the least.

You dont need the heater hose to radiator.The rest by itself will work.

 

[AuroraGirl]

Thanks for clarifying. My bad for posting wrong info. To me it makes more sense, though, hot coolant in the bigger hose for more volume to the heater core, and the smaller hose allows for some back pressure to slow the flow and let the heater core disperse more heat into the cabin, and thus, the cooler coolant flows in the smaller hose. Good to know I was wrong.

slowing the coolant circulation down wont make it hotter, the truck that is. Heat will be shed from the coolant wether it moves fast or slow

 

[jimmy78]

You dont need the heater hose to radiator.The rest by itself will work.

Unfortunately the port on the rad is there and with the trans cooler there they tend to work together. Not wanting to plug a big hole if I don’t need to