Heater core water hose routing

[timcos]

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

[wheels67]

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.

[timcos]

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

[71meangreenc10]

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

[68C15]

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

[FarmTruk]

Originally Posted by timcos

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

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...

[Stocker]

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...

[timcos]

I do have factory A/C

Tim

[rage'nrat638]

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...

[timcos]

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

[68speedalert]

Originally Posted by FarmTruk

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...

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.

[rage'nrat638]

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

[timcos]

Originally Posted by 68speedalert

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.

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.

[timcos]

Originally Posted by rage'nrat638

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

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

[68speedalert]

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)

[timcos]

Originally Posted by 68speedalert

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)

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.

[rage'nrat638]

Originally Posted by timcos

I do have factory A/C

Tim

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

[68speedalert]

Originally Posted by timcos

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.

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.

[rage'nrat638]

Originally Posted by 68speedalert

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.

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

[FarmTruk]

Originally Posted by 68speedalert

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.

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

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.

[68speedalert]

No problem FarmTruk; glad to help.

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

[timcos]

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

[timcos]

Originally Posted by rage'nrat638

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

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

[MACO]

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.

[68speedalert]

Originally Posted by timcos

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

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