1968-72 Heater w/o AC - The 1947 - Present Chevrolet & GMC Truck Message Board Network

gregz68c10 · 07-02-2011, 01:48 PM

I've had poor heating for some time in my 1968 C10. While examining the LMC parts catalog, I realized I've had my heater hoses reversed. I am certain they were this way when I bought the pickup. I disassembled the truck, restored it and put it right back the way it was.

If the hoses are reversed, could this be the cause of my cool heater? The 5/8s hose has been plumbed off the pump and the 3/4 hose has been plumbed off the manifold. It appears in the catalog that it should be exactly opposite. Heater core is installed correctly with the 5/8 hose on the bottom.

It'll be a few days before I get the heater assembly reassembled properly for a test. Just thought I'd ask if anyone had encountered this.

Thank you.

**70cst** · 07-02-2011, 02:33 PM

bump fo you ...

ChevLoRay · 07-02-2011, 03:43 PM

It's almost 100 degrees here, so heaters aren't on my mind, but I'll give you a bump.

FRENCHBLUE72 · 07-02-2011, 04:16 PM

I could be wrong but why does it matter which inlet the water goes through? If you have hot water in the heater core its gonna be hot air in the cab. Have you or did you check to see if the cable operated door was opening in the heater box to let the heat from the core into the cab? Again I could be wrong and if so ill learn something new..

eurospec1 · 07-02-2011, 04:47 PM

Quote:

Originally Posted by FRENCHBLUE72

I could be wrong but why does it matter which inlet the water goes through? If you have hot water in the heater core its gonna be hot air in the cab. Have you or did you check to see if the cable operated door was opening in the heater box to let the heat from the core into the cab? Again I could be wrong and if so ill learn something new..

I agree, i really don't think that will matter, hot water is hot water

dmack91 · 07-02-2011, 04:51 PM

I mistakenly reversed mine when I replaced my heater core. Heater still works fine - good enough that I haven't bothered switching them back yet.

gregz68c10 · 07-02-2011, 06:27 PM

I too thought that hot water should be hot water... I am using a two outlet water pump on the engine. Both water pump outlets are attached to the heater. My aftermarket intake manifold doesn't have a good source for the water (well at least it hasn't since I built an all steel fuel line for the carb).

I had luke warm air before rerouting the fuel line, which interfered with the intake manifold water source. After plumbing the heater to the second waterpump source things really got cold.

RichardJ · 07-02-2011, 07:30 PM

>>I am using a two outlet water pump on the engine<<

Are you sure they aren't both inlets?
Are you talking about a SBC?
The two outlet ports on the back of the pump push the water into the block. Water flows through the block, into the heads and out the intake manifold port to the heater and back to the suction side of the pump. If both of those ports you are talking about are on the same side of the pump as the lower radiator hose, then you have NO flow through the heater core.

My 292 had a 160 deg thermostat when I got it. Not enough heat on a cold winter night, but a 180 cured that.

gregz68c10 · 07-03-2011, 02:30 PM

Here is a photo of my present setup. The dawg gone fuel line turned out so nice I couldn't bring myself to reroute it again for the heater hose, so I tapped into the second water outlet on the pump. I thought that would solve my heater problem. You are probably right... I must have no flow to the heater with it set up as is.

http://www.flickr.com/photos/diesel-...in/photostream

http://www.flickr.com/photos/diesel-...in/photostream

07-02-2011, 01:48 PM	#1
gregz68c10 Registered User Join Date: Mar 2011 Location: Boise, ID Posts: 14	1968-72 Heater w/o AC I've had poor heating for some time in my 1968 C10. While examining the LMC parts catalog, I realized I've had my heater hoses reversed. I am certain they were this way when I bought the pickup. I disassembled the truck, restored it and put it right back the way it was. If the hoses are reversed, could this be the cause of my cool heater? The 5/8s hose has been plumbed off the pump and the 3/4 hose has been plumbed off the manifold. It appears in the catalog that it should be exactly opposite. Heater core is installed correctly with the 5/8 hose on the bottom. It'll be a few days before I get the heater assembly reassembled properly for a test. Just thought I'd ask if anyone had encountered this. Thank you.

07-02-2011, 02:33 PM	#2
70cst Senior Member Join Date: Feb 2001 Location: New Madison, Ohio Posts: 21,373	Re: 1968-72 Heater w/o AC bump fo you ... __________________ A husband can be right...or...A husband can be happy. 67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk. 1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc JOHN 17:3...The better side of "LIFE" Remember: Everyday is a good day...Some are just gooder!

07-02-2011, 03:43 PM	#3
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: 1968-72 Heater w/o AC It's almost 100 degrees here, so heaters aren't on my mind, but I'll give you a bump. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

07-02-2011, 04:16 PM	#4
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,606	Re: 1968-72 Heater w/o AC I could be wrong but why does it matter which inlet the water goes through? If you have hot water in the heater core its gonna be hot air in the cab. Have you or did you check to see if the cable operated door was opening in the heater box to let the heat from the core into the cab? Again I could be wrong and if so ill learn something new.. __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

07-02-2011, 04:51 PM	#6
dmack91 Registered User Join Date: Jan 2011 Location: Redmond, OR Posts: 763	Re: 1968-72 Heater w/o AC I mistakenly reversed mine when I replaced my heater core. Heater still works fine - good enough that I haven't bothered switching them back yet. __________________ 68 Chev C20- son has it now 83 K20 - bought from son 70 C20 - in progress

07-02-2011, 06:27 PM	#7
gregz68c10 Registered User Join Date: Mar 2011 Location: Boise, ID Posts: 14	Re: 1968-72 Heater w/o AC I too thought that hot water should be hot water... I am using a two outlet water pump on the engine. Both water pump outlets are attached to the heater. My aftermarket intake manifold doesn't have a good source for the water (well at least it hasn't since I built an all steel fuel line for the carb). I had luke warm air before rerouting the fuel line, which interfered with the intake manifold water source. After plumbing the heater to the second waterpump source things really got cold.

07-02-2011, 07:30 PM	#8
RichardJ Registered User Join Date: Apr 2010 Location: So Cal Posts: 1,470	Re: 1968-72 Heater w/o AC >>I am using a two outlet water pump on the engine<< Are you sure they aren't both inlets? Are you talking about a SBC? The two outlet ports on the back of the pump push the water into the block. Water flows through the block, into the heads and out the intake manifold port to the heater and back to the suction side of the pump. If both of those ports you are talking about are on the same side of the pump as the lower radiator hose, then you have NO flow through the heater core. My 292 had a 160 deg thermostat when I got it. Not enough heat on a cold winter night, but a 180 cured that. __________________ '67 GMC 2500, 292, 4spd, AC

07-03-2011, 02:30 PM	#9
gregz68c10 Registered User Join Date: Mar 2011 Location: Boise, ID Posts: 14	Re: 1968-72 Heater w/o AC Here is a photo of my present setup. The dawg gone fuel line turned out so nice I couldn't bring myself to reroute it again for the heater hose, so I tapped into the second water outlet on the pump. I thought that would solve my heater problem. You are probably right... I must have no flow to the heater with it set up as is. http://www.flickr.com/photos/diesel-...in/photostream http://www.flickr.com/photos/diesel-...in/photostream



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