Heater core water hose routing

[timcos]

I have also already bought a new S tube, new hoses for the ducts and new defroster vents. The other ones fall apart in my hands.

Tim

[timcos]

Anyone with a scan from an assembly manual with the inner fender bolt placement? I desire to know as much as possible before i go break some knucles.

[Stocker]

Sorry Tim, I lost this thread and then forgot . Sounds like you have the hose routing OK, but here's what I have anyway, pretty much as speedalert posted:

No heater hoses on water pump. 5/8" (source) hose from intake manifold (near thermostat) to valve on inner fender (like rage'nrat's first pic), then to lower heater core nipple.

3/4" return hose from top heater core nipple to radiator nipple.

[timcos]

Yes...all I am missing is the valve. I have a straight shot from the intake to the lower heater nipple.

Tim

[mdazb]

Okay after reading all this I need to ask this. Before I got my 72 350 (no a/c) they had the heater core replaced. My core is mounted as such. The 5/8 hose is on top and routed to the intake. The 3/4 hose is on the bottom and mounted to the radiator. I get heat but I wonder if the heater core was mounted upside down. And, if that even matters? Both hoses are hot, radiator's cool after a 30 mile freeway ride and my gauge reads a little above the C. Any thoughts?

[neteng01]

Hi All,

I know this is an old thread, but I have an interesting question that maybe someone can help me with. I purchased a new to me 1972 C10 a couple months ago. The PO changed out the original motor with a 1989 Trans Am 2-port 350 motor with a serpentine belt. He told me that the water pump rotates backwards on these motors?? no idea on my side. The problem is that I cant get my heater to work for the life of me. I have a new core, blend door works fine, all new vacuum lines, all new heater hoses, cleaned out heater box so no obstructions. Blower works on all speeds, all new ducting under the dash, and just about everything else is working.

My question is this, the PO ran the heater hoses with the 3/4 hose from the top port of the heater core to the radiator, and the 5/8 hose from the bottom port of the heater core to the water pump. He has several temp sensors in the intake for electric fans and temp gauge. The hoses seem to get hot, slowly, but my heater always blows cool, even with all doors in proper positions. The only thing I have not changed is the thermostat since the motor seems to run at normal temps.

I am at my last nerve here and cannot seem to figure what the issue is. I know that modded motors can cause some challenges, however, he swears that it all worked last time he tried and that I must have something clogged or wrong. Could the water pump connection be the issue here?

Any help or opinions would be greatly appreciated. My C20 is warm as ever but I am feeding as it should via manifold and radiator connections.

[Andy4639]

This is the best I can do. It's straight out of the manual. From what I see it's showing the bottom heater core hose going to water valve then going to intake.
Top heater core hose going straight to water pump.
These are both for AC trucks, I don't know if a non AC truck heater hose route would be any differant are not.

[neteng01]

Thanks for the input, I looked in the manual as well, and the problem I have is the xfactor of the water pump/radiator connection on the 2 port motor. It seems to me that it should go as the pics describe, but with the PO motor, there is not a manifold input I can use and the water pump circulates in the opposite direction. Almost makes me wonder if there is a built in bypass with the motor configuration. It is quite the conundrum I think...:p-)

[Andy4639]

U are going to have to put a connection on the block to get the warm water into the heater some how. Take a senor out of the engine block and put a nipple with a tee in it for the water and senor both if u have to.
The water line going to the radiator is the one you need to change for sure. My opinion anyway.

[cigar-]

Am working on reviving a 1971 C10. It has no heater core but I have a used one that's good.

What is the positioning of the core in the heater box? Which opening (top or bottom) houses the larger of the two tubes coming out of the heater core?
Posted via Mobile Device

[Stocker]

Originally Posted by cigar-

Which opening (top or bottom) houses the larger of the two tubes coming out of the heater core?

Return hose is the larger and is on top.

[cigar-]

Thank you Stocker.

This forum is a wealth of information.

[cigar-]

One other thing.....

Is it necessary for ther to be a valve in one of the heater hoses? I see from previous posts that the factory had a vacuum operated valve in one heater hose.

My truck has no A/C so I am wondering if it would be fine to run no water valve at all.