Heater Hose ?

[1970 CST Short Wide]

On a 71 Non AC truck. which heater hose goes where ? Does the top one comeing out of the firewall go to the rad or the intake?
I forgot to note it when I took them off.

Thanks in advance

[jef5150]

here ya go........jeff

[lukecp]

Crap.....looks like mine are on backwards!

Also...which end of the heater core is supposed to be on the top on a V8 truck? I think the big end is on the bottom of mine...i may have to go check though.

[1970 CST Short Wide]

Thanks

[lukecp]

Humm....i think mine is on the bottom....so it should be OK. Would the air flowing through the heater core backwards give me bad heat? My heat works OK....but not great considering i have a one year old core and blower motor.

[Blue Beard]

jef5150,

Which book did that pic come from.........?

Don't believe I've ever saw a heater hose going to the radiator before.....

There was a thread started about the topic of the heater hose going to the radiator. Check the search and see what comes up. I cant remember what the outcome of it was....

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Cap'n Hook
Member

Registered: Jun 2003
Location: Texas Hill Country
Posts: 38

Q: New radiator, but no heater hose nipple!
Gotta new 4-core radiator for the Jimmy from PartsAmerica but there's no prevision for the return heater hose. Can I just run it back to the water pump, instead?

Thanks guys, and great forum!


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08-24-2003 05:50 PM



adamls
Gotta Startem Early

Registered: Oct 2001
Location: Amarillo, TX, USA
Posts: 293
Contributor
No, the water needs to make a complete circle that goes through the engine and then through the radiator. If you send it right back into the pump then it will never cool off.


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08-24-2003 05:57 PM



Cap'n Hook
Member

Registered: Jun 2003
Location: Texas Hill Country
Posts: 38

So, then how do I get this back to the tank? Do I need to go have a new nipple fitted to the new radiator for this hose?

Guess I know why I only paid $150 for this thing now!


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Last edited by Cap'n Hook on 08-24-2003 at 06:17 PM

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08-24-2003 06:02 PM



tom hand
CCRider

Registered: Feb 2000
Location: Olive Branch,MS,USA
Posts: 1854

Yes you can run it off the intake and back to the water pump...that's how mine was run from the factory. I have never seen a 67-72 that had the nipple on the radiator from the factory, I aways thought that was a 73 up thing,[and the radiator will bolt right in] but these trucks were built at several different places so there is no telling


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08-24-2003 06:21 PM



68 Stepside
On the Road

Registered: May 2000
Location: Central Illinois
Posts: 3464

I agree with Tom. Millions of GM cars/trucks have one hose running to the pump, and the other to the tank. You should have no problems doing it that way.


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08-24-2003 06:31 PM



Cap'n Hook
Member

Registered: Jun 2003
Location: Texas Hill Country
Posts: 38

Ya'll are confusing me! Ok, the intake is already used to feed the heater core, and the return line was going back to the radiator, directly from the heater core. Now this new radiator doesn't have a prevision for this return line from the heater core, so I was gonna run it to one of the two holes in the water pump, one being on top and the other on the passenger side of the water pump, using the latter of the two! Seems to me, once the thermostat opens up, all the coolant will be cooled!? Yes/No?


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08-24-2003 06:35 PM



tom hand
CCRider

Registered: Feb 2000
Location: Olive Branch,MS,USA
Posts: 1854

Yes run it to the hole on the passenger side of the waterpump it will work fine...this is for the heater it has nothing to do with cooling the engine


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08-24-2003 06:49 PM



Cap'n Hook
Member

Registered: Jun 2003
Location: Texas Hill Country
Posts: 38

Just a question, but then why did the radiator Im replacing have the return heater core hose running to the radiator? Maybe a wrong replacement radiator previously, or something of the nature?

And I'll be picking up some new parts tomorrow, including the thermostat housing, thermostat and upper and lower radiator hoses, and the bung to fit the water pump for the return heater hose! Im thinking 195 degrees is a bit too hot to run here in Texas summer heat, but 160 is too cool for winter. So I'm gonna pickup a 185 thermo! These have to be the original thermostat housing and metal upper radiator hose, cuz they both have rusted pieces inside them, some pieces bigger than my small finger nail!


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Last edited by Cap'n Hook on 08-24-2003 at 07:03 PM

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08-24-2003 06:59 PM



jef5150
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Registered: Apr 2003
Location: stockton,california
Posts: 540
Contributor
did you order the correct radiator????????????
manual tranny and auto tranny radiators are hooked up differently,,,,,,,,,,,,,,,,,,,,,,,,,,


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08-24-2003 07:00 PM



FRENCHBLUE72
Senior Member

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It seem's to me the truck's with automatic's had the hose going to the radiator and manual's had the water pump action going.. But I could be way off base.


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08-24-2003 07:03 PM



Solver
Senior Member

Registered: May 2000
Location: Storm Lake, Ia
Posts: 495

Most of the trucks I have had the radiator had a port on it for the heater. The aftermarket radiators I have ordered do not have this port on them now.I wonder if anyone makes it that way anymore.I have had to use the spare port on the water pump.That plug on the water pump is kind of hard to unscrew after 30 some years


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08-24-2003 07:07 PM



Cap'n Hook
Member

Registered: Jun 2003
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Posts: 38

Supposedly this is the radiator for my application, AT with A/C! Didn't really pay attention to the heater hose bung not being there in the picture before I ordered!


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08-24-2003 07:07 PM



jef5150
"Grind -n- Gears"

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Location: stockton,california
Posts: 540
Contributor
you might of ordered the wrong type
they are routed differently.........jeff

jef5150 has attached this image:


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08-24-2003 07:28 PM



Hotrod70C10
Senior Member

Registered: Dec 2002
Location: Oklahoma
Posts: 709

That's interesting! I've got the typical v8 manual trans hose setup on mine. It is a factory 350 w/ th-350 tranny. I'm guessing the radiator was replaced some time ago before I bought it though.


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08-24-2003 09:01 PM



JimKshortstep4x4
Senior Member

Registered: Jul 2001
Location: Kentwood,MI,USA
Posts: 1782


My radiator repairmen tells me that he has seen the nipples on the radiators mainly on vehicles with AC. It also makes sense that automatics could benefit from the return being in the radiator. If it were my vehicle and it had air, I would want the nipple on the radiator.

Jim



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08-25-2003 07:39 AM



Bill72BB
Thats the Hillbilly way

Registered: Jul 2001
Location: Torrance,Ca
Posts: 2573

When I ordered mine it had the return to the radiator , it was a Modine .


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08-25-2003 07:59 AM



adamls
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Now, I am confused.


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08-25-2003 08:11 AM



Maximum Overdrive
Senior Member

Registered: Apr 2000
Location: Montana
Posts: 1009

I have had a few automatics and none of them had a return line for the heater core on the radiator. Only tranny fluid lines to them. They all had the set up of the heater core hose going back to the waterpump.


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08-25-2003 09:12 AM



Alex
Senior Member

Registered: Jan 2000
Location: Blaine, MN
Posts: 718

Mine (no A/C) had the heater hose nipple and I replaced it (2 core) with a 4 core radiator with no nipple so I took it to the local radiator shop to have one installed. I lucked out as the guy did it for free.


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08-25-2003 09:21 AM



72c10step
No, rubber side down!

Registered: Jul 2003
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Posts: 341

I bought a replacement radiator for my truck a month or two ago. It came with the heater line fitting on it, as well as the tranny cooler line fittings. The old one I removed had the same setup. My truck has a 350/AT and no A/C. Now only if I hadn't dropped the old Voltage Regulator, which put a pinhole leak in the brand new radiator. Doh!

72c10step has attached this image:


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08-25-2003 11:04 AM



Cap'n Hook
Member

Registered: Jun 2003
Location: Texas Hill Country
Posts: 38

Well, my Jimmy has A/C and auto and Im gonna try rerouting the heater core return to the water pump and see what she does. I figure it being a 4-core and all, it will probably cool just fine. Also, Im getting a lower degree thermostat to compensate for the higher volume of water going thru the water pump now!


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08-25-2003 02:10 PM



dubie
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Registered: May 2000
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I just went through this exact same thing on the board a few weeks back. You can route the one through the intake and the other goes in through your water pump plug. I have seen both automatics and manual trannies with this exact same setup. It will work!!


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08-25-2003 02:15 PM



smitty62
Senior Member

Registered: May 2002
Location: North Carolina
Posts: 277

(A) Modine still makes the radiator with a nipple.
(B) OK to feed back into the water pump--no biggie!
(C) If you really want the nipple, take it to a radiator shop--(cheaper than return shipment if it was shipped to you)


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08-25-2003 02:29 PM



busterwivell
Senior Member

Registered: Jan 2002
Location: Sahuarita, AZ USA
Posts: 1139

I didn't have a fitting in the radiator I took out, but did on the new 4 core I got at Pomona. Just got a cap for it and secured it with a hose clamp.


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08-25-2003 03:47 PM



Dusti
Member

Registered: Jul 2002
Location: Washougal WA
Posts: 154

Radiator
I had to go check what was in my truck,some previous owner replaced the original one with 1 that has the nipple on the radiator that is blocked off and has the conections for auto tranny lines that are not being used since its a 4-speed.

Just adding more to the confusion

Bob W


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08-25-2003 05:02 PM



jef5150
"Grind -n- Gears"

Registered: Apr 2003
Location: stockton,california
Posts: 540
Contributor
ac??????????????

quote:
--------------------------------------------------------------------------------
Well, my Jimmy has A/C and auto
--------------------------------------------------------------------------------

you should of told me that in the begining,,,,,,oh well,now you know how to hook up the a/c,,,,,jeff

jef5150 has attached this image:


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08-25-2003 05:26 PM



All times are GMT -8 hours. The time now is 07:26 PM.

[DavidM]

nice diagram

[Longhorn Man]

Not that it really matters...as long as it is all hooked up, it'll have hot water in it. Top to bottom, bottom to top, as long as it has hot water and air going through it, you'll get heat.

[dinnut]

the heat doesnt work in either of my trucks. and i dont even wanna try and get it to.

[SEVEND2]

Here is a Pic of how my heater hoses are set up, and it works great

.....
Smaller hose to the manifold and the slightly larger hose to the Rad nipple

[lukecp]

SevenD2, mine is routed just like yours, except my lower large hose is going to the water pump.....

[BLACK AND BLUE 67-72]

My old 72 radiator has the nipple in the radiator and so does the new one.

[gonebad2]

This has been a fantastic post..I'm still confused...lol. Any members want to do a recap of what we have learned here. I'm getting ready to do mine next weekend. I'm using Aeroquip hose and fittings ( braided stainless AN-10) and don't want to mess this up. I bought a new heater core and am going to try and sweat copper fittings (3/4") female on the inlet and out. I have a few hundred bucks invested in this and don't want to mess it up.

[Blue Beard]

What we've done here is mass confussion.................

[jef5150]

The picture i posted came "directly" from a "factory 1971 chevy service manual"!,That is the way these trucks came from the factory!!!!!!!"Back then",radiators were made in 2 versions,manual or for an automatic(which had a seperate tank in the radiator for tranny lines),either radiator "WILL" work,,,,,,but if your useing an older style that came from an automatic,and put it in a truck that "now" has a manual tranny in it ,you have to plug the 2 openings where the tranny lines usta go..same applys if you switch from a manual tranny to an automatic,the radiator "will" work,but your gonna hafta add an aftermarket tranny cooler to connect the tranny lines to...... To make things even more complicated,most of todays "aftermarket radiators" come universal.So,,,,if you or p/o changed the radiator, or you've switched from a manual tranny to an automatic,or if youve put an "aftermarket radiator" in your truck... those "factory" pics,may be a little different,,,,,,,,,, ,,thats why everyones "set up" is a little different.........Oh 1 more thing,if you changed the motor,or manifold,again the set-up may be a little diferent jeff

[BLACK AND BLUE 67-72]

Yes, those are the same pics I have in my 1972 Service Manual also.

[SonomaComa]

How do you mount the Heater Core in the Housing? Does the 5/8" or 3/4" inlet on the Heater Core get mounted on the top? My two heater hoses go from either the Water Pump or the Intake Manifold next to the top Radiator Hose. Any pictures of the correct way to mount them?

[Stocker]

3/4" nipple on top.... this is the water exit from the heater core. Water enters the core through the 5/8" nipple at the bottom.

[SonomaComa]

Originally Posted by Stocker

3/4" nipple on top.... this is the water exit from the heater core. Water enters the core through the 5/8" nipple at the bottom.

Ok, and does the Inlet get connected to the top of the Intake Manifold and the Outlet gets connected to the Water Pump?
I thought it was like Radiator. I was going to mount it the other way around so the water flows in from the top and out of the bottom.
What would happens the cooling system was not absolutely 100% full, how would the coolant travel up from the bottom to the top of the Heater Core? Would it just sit in there and bubble up?

[Stocker]

Depends, need details on your truck and will probably need to search.... unless it's the same as mine.

Coolant goes from bottom of heater core to top because it's hot.... hot liquid rises same as hot air rises.

[SonomaComa]

Thanks, I have 1970 GMC C-20 without A/C.