Heater core water hose routing
 

My heater core hoses go like this...from the intake manfiold to the upper heater core connection...then from the bottom heater core connection to the radiator...sort of pours back in.

I have seen in pics on this site where the hose that goes to my radiator is actually conneected to the water pump.

I get the most heat at higher rpms...when idling I get very little heat. Is my setup correct?

Thanks,

Tim

Re: Heater core water hose routing
 

Hmmm My top hose on heater core goes to the water pump and the bottom hose goes to the manifold. Nice and toasty. lol

Salt lake is freeeeezing man.

Re: Heater core water hose routing
 

Yes it is freezing.

I thought the supply was the top of the intake...as it would supply before the thermostat opened....and the outlet was the radiator hookup.

Tim

Re: Heater core water hose routing
 

Maybe someone put in a new core and put it in upside down, easy to make the mistake,,,the pump should go to the top.

Smitty

Re: Heater core water hose routing
 

IIRC the bottom of the core is the inlet while the top is the return. mine returns to the WP.

Re: Heater core water hose routing
 

:confused: I don't think you'd want the heater core being supplied by the intake. That would seriously slow down engine warm-up. No use supplying cold water to the heater core. Once the water is warm, the thermostat opens, flowing warm water thru the system, and presto...warm air...

Re: Heater core water hose routing
 

Maybe the drawings in this thread will help. http://67-72chevytrucks.com/vboard/s...d.php?t=188679

timcos, if you have factory A/C, I can check my heater hose routing for you...

Re: Heater core water hose routing
 

I do have factory A/C

Tim

Re: Heater core water hose routing
 

your sig does not say what engine you got? but the intake is 5/8 hose and the water pump is 3/4 hose if that help's
i have a 69 350 engine and the heater will burn you out...

i have seen some radiators that have a connection for heater hose's

also i have a/c on my truck with a heater control valve inline this might be a problem as well. . this is closed with the a/c on and open all other times..

heres a few pictures...

Re: Heater core water hose routing
 

You know, the pics in that post which I now find in my manual shows the water hoses going form the intake manifils to the lower connection on the heater core and the upper connection of the heater core to the radiator.

I just verified it on my truck...it is like that. I guess I remembered it incorrectly in my previous posts.

I do smell anti freeze slightly everyone once in a whiile...so mybe my heater core is bad.

I bought a new one today..

Now I have to drop my inner passenger fender, remove the 4 bolts holding the inner heater core box tot he firewall, the two screws on the inside of the cab holding that same box up...and replace the core.

I also have a straight hose form the intake to the lower connection of the heater core...no valve as shown in the pic.

Any other thoughts?

Tim

Re: Heater core water hose routing
 

Sorry FarmTruk, but you couldn't be farther off.

Water circulation on a Chevy V8 goes from the waterpump, thru the engine block and up to the thermostat. Coolant goes out the intake, to the BOTTOM connection of the heater, out the upper connector and returns either to the waterpump or the radiator, where it is repumped by the waterpump and so on and so on.

Once it gets warm enough for the thermostat to open, then the coolant goes thru the upper hose into the radiator and so on and so
on.

timcos,

Are both heater hoses hot? If so, you need to check the blend door.

Do you still have a coolant shut off valve? It should be open unless you have the a/c on max (recirculate).

If the hose coming from the intake is hot going into the heater and the hose going to the radiator is cooler, your core may be clogged. Take a garden hose and adapt it to it and flush it out from both connections.

Re: Heater core water hose routing
 

you more than likely are going to find a crap load of junk in the heater box..

i have a roll of galvanized window screen which i cut and placed under my cowl to keep the leafs and sticks and all the other crap out..works great. looks like it was supposed to be there as well..

buy a good quality heater core..i used a roll of plumbers putty to reinstall the box to get a good seal and keep the rain water out..

i would replace the control vlave at the same time..

i used someone else's picture here :metal:

Re: Heater core water hose routing
 

Yes...both heater hoses are very hot when idling (and for that matter at high RPMs as well).

There is no inline valve of any type...straight hose.

Re: Heater core water hose routing
 

I bought the cowl leaf guards from LMC a few months ago...other projects (and 0 degree temps) have prevented me from working much on my baby.

If it got to 35...I could warm up my garage with my kero heater.

I bought a good core today. Like I said above...my next step is to try and warm up the garage.

I do get some heat so it is not critical yet.

I have seen that pic...I will take a ton myself.

Tim

Re: Heater core water hose routing
 

If they are both hot and you have no heat, the door that moves with your temp lever is not closing all the way (blend door)

Re: Heater core water hose routing
 

I thought about that too.

But...if I am stopped (at a 7/11 or something)...and rev it to about 2,000 RPM...it gets very warm to almost hot blowing out of the vents.

Re: Heater core water hose routing
 

there should be a valve inline on the heater hose and you need to find where the small vacuum line is on your truck that hooks up to it.. if you have a open vacuum leak there your vacuum operated switches and diaphragm on the passenger kick panel most likely is not working correctly...

ant trucks fun....

heres another picture i am using of someone elses this one is in the cab looking at the hole

Re: Heater core water hose routing
 

What about at a QuickTrip?:)

Have you checked both hoses to see if hot and then checked the air from the vents, and it's cold air?

Ragenrat...

A vacuum leak is possible, but I don't think that will change the temp of the air, just where it blows.

Re: Heater core water hose routing
 

yup i agree i just to throw that out there because we have a vacuum hose floating around somewhere thats not hooked up :jdp: :jdp:

Re: Heater core water hose routing
 

:dohh:

68speedalert, I stand corrected. That's why I love this place. Thanks for clearing that up. :o

Timcos, good luck with yer project. Didn't mean to steer ya wrong. I'm glad there are others here to keep ya' on the right path. :)

Re: Heater core water hose routing
 

No problem FarmTruk; glad to help.

Ain't much I know for sure.....got lucky for a change.

Re: Heater core water hose routing
 

Yes...the hoses are hot. The air is not cold. It is certainly warner that 9 degrees...and it keeps the cab from freezing...but I should be cooking myself out of the cab the way these things heat...and that is what I want.

So I think it is the core...and I will clean the blend door and make sure it all works well...heck it is 35 years old in a few months.

Tim

Re: Heater core water hose routing
 

There isa vacuum hose I have plugged with a golf tee...sitting on the passenger innner fender.

BTW...how many bolts on that inner fender?

Tim

Re: Heater core water hose routing
 

Before I replaced my heater core I could feel the heater tempature drop when at a stop light. After installing the new heater core I can get the truck cab too hot inside and I still need to fix some holes in my cab.

Re: Heater core water hose routing
 

Check the hoses with the blower on high. If they are still both hot, you've GOT to have some kind of blend door problem or air not going thru the box correctly.

I guess in theory, your heater core could be letting the coolant bypass the actual core, because of a hole in the side tank......I've never seen that in a LOT of years of wrenching.......

You say you have a manual....I'm not sure if it's there, but later model manuals will show how the air is directed thru the box; showing how the blend door passes it thru the core (for heat) or bypasses it to get cooler air from the outlets.

It sounds like your gonna do the core, not a bad thing for it's age. Try to look at all the stuff when it's apart, looking for any holes or gaps in the system.

good luck

Steve

Re: Heater core water hose routing
 

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

Re: Heater core water hose routing
 

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.

Re: Heater core water hose routing
 

Sorry Tim, I lost this thread and then forgot :o . 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.

Re: Heater core water hose routing
 

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

Tim

Re: Heater core water hose routing
 

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?

Re: Heater core water hose routing
 

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.

Re: Heater core water hose routing
 

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.;):chevy:


http://i1233.photobucket.com/albums/...titled-1-1.jpg


http://i1233.photobucket.com/albums/...9801DADABF.jpg

Re: Heater core water hose routing
 

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-)

Re: Heater core water hose routing
 

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.;):chevy:

Re: Heater core water hose routing
 

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

Re: Heater core water hose routing
 

Return hose is the larger and is on top.

Re: Heater core water hose routing
 

Thank you Stocker.

This forum is a wealth of information.

Re: Heater core water hose routing
 

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.