'79 heater hoses

['79squared]

So, looking all over and cant find anything specific to 73-80 heater hose routing. Opinions are also all over the place.
My heater box inside the cab under the dash (measured 125) gets so hot that the inside of my truck is almost unbearable in hot weather. And yes I have checked and my motor does not run hotter than it should. About 200 on the block and 180 at the heads.
So a couple of questions here.
1. Are my hoses routed wrong? Black one being the top, braided being the bottom.
2.Which connection at the heater core (top and bottom) is in and which one is out? And where should they be connected? (intake, radiator, water pump)
3.Can I just plugging both the passages at the intake and water pump? Will this mess with the flow of the motor? As I dont need a heater at all because its a fair weather truck anyways. And no my ac is not connected and wont be.

[Blessed66]

For whatever it's worth, that's exactly how my 84 is routed. Or was. I had a massive heater core leak and ran the line from the intake straight over to the radiator. Once I bypassed the core, it didn't change anything except not puking out all the coolant into the passenger floor board and trying to overheat. I'd call that a win.

If it's fair weather, I'd say buy a plug for the intake and use a cap on the radiator. Both are usually available at the parts houses for cheap enough. Should be fine.

[tucsonjwt]

I installed a shut off valve (3/4" PEX valve from Home Depot) on the 5/8" line, which I think is the inlet line, with 3/4" being the outlet line. (Not sure on this, but it is what I did.) It should reduce your heater core temperature. It works with non a/c trucks as well. My pic in the thread below shows which hose is which - size of 5/8" is marked on the hose in the pic.

See this thread:

http://67-72chevytrucks.com/vboard/s...d.php?t=676613

You can also add a bypass hose and two nipples as shown in the thread above. Then you won't have to figure out which hose is in and which hose is out. Since you want a permanent bypass, that might be a better option for you.

['79squared]

I've looked at the valves and haven't gotten one yet. Seems easier to just block both holes Im thinking. Either way I think my hoses are running opposite of what they should be but not sure. Well seems to me if the water pump flows out, it should be the feed. Not the intake which is way hotter. So my thinking was water pump feeds and then returns through the intake. But Im still not sure about that either haha.

[kenn]

Hello
My 72 has a valve in the 5/8 line (feed to core) that opens and closes with the hater switch in the cab.
If you don't want heat "ever" than you can remove the lines at the intake and at the radiator.
Cap both lines.
The coolant in the block rotates thru the pump(in one mounting leg and out the other)and when it gets up to temp the thermostat opens and lets it out to the radiator.With the cap on, the coolant stays in the rad untill the stat opens and starts flow thru the rad and block.
I hope this helps.
K.E.N.

['79squared]

Its all good info. Some new some not. Thanks kenn. The one thing (because I have looked and have posted this elsewhere) is that no one can seem to answer what the correct way is that water flows through the heater core. Maybe there is no correct way. I dont know. I had read that it should run from the pump to the heater core and then back to the intake. I have also read the opposite. And then of course there is the option for the radiator.
One of the big questions in my mind though is direction of flow or it just doesnt matter.

['79squared]

Seen it explained that it needs to fill bottom first and flow out the top. This might seem to also keep out trapped air that may form if top filled? Also then, looking at the pic, the 5/8 (bottom) would be the inlet and 3/4(top) the out. At that point, where do you feed it from? The intake or the water pump?

[tucsonjwt]

If you install a bypass hose it won't matter which hose is in and which hose is out. All coolant will recirculate to the original source.

[Titomars]

the coolant flows from the intake to the core and returns via the pump or the radiator, depending on which you have. The hottest coolant goes to the core always, which is the closest port to the backside of the t/stat as in the crossover on the intake.

[Liberty]

Factory on my 82 has the hoses going down to the Wheel Well.
I installed a 1/4 turn ball valve on the 5/8 hose to cut off circulation to the heater core and has made a noticeable difference.

At anyrate, the 5/8 hose goes to the manifold on the engine. 3/4 to the radiator.

Judging by your picture, yours is set up correctly, although the heater hoses are not supposed to be in contact with your Accumulator/Dryer.

Feel free to plug away, your engine is not going to care at all.

[Titomars]

Originally Posted by Liberty

Judging by your picture, yours is set up correctly, although the heater hoses are not supposed to be in contact with your Accumulator/Dryer.

Feel free to plug away, your engine is not going to care at all.

While you are 110% correct about the contact with the accumulator his A/C is not hooked up and working.

[Bigstevex4]

That set up doesn't work so good when its cold. like below zero cold I run the hose to rad to bottom of the block. your dumping all your warm water in the cold rad.

['79squared]

Ya seems more than one way to get it done. I just need to decide which Im gonna choose. About the only time it will even see rain is if I accidentally get caught in it. I don't even have a wiper motor in it right now. So cold weather (even in Washington state) doesn't play a part for me.
As for the ac, yes it is not hooked up and may never be while I have it. Although I do have all the parts. The hoses mounted there are only a temp situation. I lost the fender mount when I had the front all stripped down.
And again thanks for all the help and hopefully if someone else does a search down the road it will help them also.

[Chevy_mud_truck]

The feed line (inlet) you want it coming from the intake that way you get better heat because it hasn't went through the radiator to cool it down and the return (outlet) goes to the radiator or the water pump

[wilkin250r]

The intake manifold is always the feed. It's been a while, so I can't remember if that is the 5/8 or the 3/4, so I'm not sure which side of the heater core it goes to, but the manifold is the hot water coming out of the engine and feeding the heater core.

The return side varies. On trucks with automatic transmissions, the return fed back to the radiator. I believe the purpose is to add a little bit of heat to radiator core and thus the transmission fluid before the thermostat opened up. On Manual transmission trucks, the heater return line went back to the water pump.

[motornut]

When ordering a rad some shops still ask auto/manual cause of the extra pipe in the rad.
I agree better winter heat/faster running block to core.
I'd use a valve,not sure how your weather is but some nights can be cool/damp.
my 79 heater is still hooked like this

[motornut]

the other post on it

http://67-72chevytrucks.com/vboard/s...d.php?t=676613

['79squared]

Ah yes . You have a picture I've been looking for that shows what I wanted to see thanks. Although mine looks to be correct, something has to be done and I have a couple of options. Its not the nicest truck around but Ive put plenty of time into cleaning my "play toy" and it only gets driven on nice days.