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Old 05-07-2017, 09:30 AM   #1
Sixball
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Heater Core Outlets. Which is Which ?

I just put a 454 in my 94 GMC Sierra 1500. I didn't hook the heater core outlets up because I didn't have any hose on hand at the time. Now I have the hose, but I didn't know which line went where and if it mattered?

So passenger side goes to?
And drivers side goes to?

Thanks, I'm finally working out the small electrical gremlins from ditching the TBI and going carb.
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Old 05-07-2017, 09:43 AM   #2
speedygonzales
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Re: Heater Core Outlets. Which is Which ?

Mine has the same core but different engine.

Passenger side outlet connects to the water pump

Driver side outlet connects to the block
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Old 05-07-2017, 10:18 AM   #3
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Quote:
Originally Posted by speedygonzales View Post
Mine has the same core but different engine.

Passenger side outlet connects to the water pump

Driver side outlet connects to the block
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Thanks
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Old 05-07-2017, 06:35 PM   #4
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Thanks
I looked at my old radiator and one hose went to the radiator. The new radiator has the same hose barb.

My aftermarket intake has a spot for one hose, and the radiator has the barb.

So, which one goes to the radiator? And what one goes to the intake?

Thanks
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Old 05-08-2017, 11:28 PM   #5
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Re: Heater Core Outlets. Which is Which ?

This is how I had my big block setup in a 88 I had. Hope this helps you some.
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Old 05-09-2017, 06:25 AM   #6
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Re: Heater Core Outlets. Which is Which ?

Quote:
Originally Posted by Sixball View Post
I looked at my old radiator and one hose went to the radiator. The new radiator has the same hose barb.

My aftermarket intake has a spot for one hose, and the radiator has the barb.

So, which one goes to the radiator? And what one goes to the intake?

Thanks
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Don't see it connecting to the block and the radiator. There wouldn't be enough flow in that case. Never saw one hooked up that way before.

Are you sure you're not confusing either a transmission cooler line or an oil cooler line to the radiator?

If a radiator has a cooler built in, it will have two ports one on top and a lower one.

Mine has 2 coolers, engine oil on one side and tranny on the other. I'll put money on you're confusing an oil cooler line.
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Old 05-09-2017, 07:50 AM   #7
95 S_Trucker
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Re: Heater Core Outlets. Which is Which ?

Some of the 88-94 trucks had one of the heater hoses going to the radiator.

If you buy any kind of factory replacement radiator, you will find a 5/8" barb sticking out of the radiator(between the rad cap and the upper fitting for the trans oil cooler. They supply a cap if you don't use the fitting on the radiator.

If the old one was at the radiator, that's where I would put the new one.
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Old 05-09-2017, 08:34 AM   #8
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Re: Heater Core Outlets. Which is Which ?

Quote:
Originally Posted by GM-power View Post
This is how I had my big block setup in a 88 I had. Hope this helps you some.
From memory my pump doesn't have that other outlet (unless it is plugged) I do have the little short hose connected just like your picture though.

So the donor truck wasn't running that second water pump hose off of it.
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Old 05-09-2017, 08:40 AM   #9
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Re: Heater Core Outlets. Which is Which ?

Quote:
Originally Posted by speedygonzales View Post
Don't see it connecting to the block and the radiator. There wouldn't be enough flow in that case. Never saw one hooked up that way before.

Are you sure you're not confusing either a transmission cooler line or an oil cooler line to the radiator?

If a radiator has a cooler built in, it will have two ports one on top and a lower one.

Mine has 2 coolers, engine oil on one side and tranny on the other. I'll put money on you're confusing an oil cooler line.
My GMC with the 350 I took out had a tranny cooler. I yanked it. I also yanked the stock radiator. The stock radiator has two tranny line conections, bottom big hose, top big hose, overflow, and the barb right below the overflow that is in question.

My aftermarket 4 core aluminum radiator has the exact same outlets in the exact same spots as outlined above.

I took pictures before the swap, but I was more concerned with electrical, so the hoses didn't get documented. UUUGGGHHHH !
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Old 05-09-2017, 08:44 AM   #10
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Re: Heater Core Outlets. Which is Which ?

Quote:
Originally Posted by 95 S_Trucker View Post
Some of the 88-94 trucks had one of the heater hoses going to the radiator.

If you buy any kind of factory replacement radiator, you will find a 5/8" barb sticking out of the radiator(between the rad cap and the upper fitting for the trans oil cooler. They supply a cap if you don't use the fitting on the radiator.

If the old one was at the radiator, that's where I would put the new one.
That's what I'm trying to figure out. I remember taking them off. They were hard lines at the core, then rubber. BUT, I had factory air too, so I am confused with the hoses I took off (and now long gone in the trash) Does anyone have an underhood shot of a 94 ? Showing where the heater core lines go?

As I said in an above post, I had a separate factory tranny cooler I took out during the swap
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