66 318 Poly engine no Heat issues....need help!

hey guys..thought i would start a new thread with my current issue....

im not having any hot air coming out of my vents...all cool...no matter how hot the engine. so when i bought the car i noticed at one point it has leaked some kinda a coolant/refrigerant on my carpet on passenger side...right under my heater core/evaporator....since i have a factory AC car my heater core is attached to the AC thingy....

in a previous post someone had mentioned that before i go and take out half my dash and replace the heater core that it may have a bad heater bypass valve...and to check my heat in the hoses under the hood and see what is going on. so i worked on this a little yesterday and what i found out is kind of head scratching... the little hose that go's from the water pump to the intake is buring hot(as it should be), but the hose from the water pump to the firewall is not warm at all, cool to the touch, the hose from the intake to the firewall is not warm at all, cool to the touch...very strange..so if i grab both hoses say in the area over my valve cover before it go's into the bypass valve in my firewall, both are cool as can be like the engine hasnt even been ran at all....

all this was after about an hour drive yesterday afternoon, so the car was good and hot for sure to operating temperature...i did all this checking while car was running also, and still no heat, no hoses warm to the touch etc....very strange...so i started running possibilites thru my head???

1. is the hoses hooked up wrong(it has mostly new hoses this year)
2. is my water pump not working?(car does not over heat and no seapage from pump)
3. is my thermostat stuck or bad?(still think my car would overheat if this the case???
4. does it need a bypass valve and a heater core both and then things would work properly???

keep in mind my AC worked earlier this year for about 3-4 hours then it lost its refrigerant, so im wondering if replacing the pieces under the dash if that would cure both my problems of AC and heat back to working normally. here is a couple of pics of how things are run under my hood....no comments on how dirty it is please, i havent gotten to that part of the car yet....:idea1:

thoughts? ideas? am i screwed? :icon_hang:

If top rad hose is hot thermostat is open,water flowing by rad neck,cap off,will show pump flow.Be careful please.I would take the two heater hoses join them and see if they get hot,this would at least show the restriction is in the heater.

Take the heater hoses off the car and see if they're clear, I've seen all sorts of things over the years when it comes to dealing with leaking? heater cores.
Some of the things i've seen used to block heater hoses (on purpose) are......marbles, bolts with the head cut off, mutant amounts of silicone pumped into the hose.....then refitted.

Sorry Don, just reread your OP, I missed the bit about mostly new hoses, I'm wondering if someone at some stage has used one of those Anti Leak type products in the cooling system. Some of those can be pretty nasty......they'll block anything, not just the leaks.
Personally,as a starting point i'd take all those heater hoses off the firewall.......stick the garden hose in all those heater related fittings to see if the water flows freely.

is it me or shouldn't the hoses be hot to the touch up close to the firewall? like over the valve cover area? while the car is running and heater is on, you grab those hoses shouldnt they be the least bit hot??? these are not...

i put the hoses on myself, ive had all the hoses off by the firewall...im wondering if something is blocking it down on the block or intake...

maybe the people before me that owned the car knew the heater core was busted and blocked the water flow off for some reason....dunno....scratching my head.

If the water isn't flowing in a circuit, through the heater core and back to the engine it would take forever for the firewall end of the hose to get hot.
By the sound of it, it's getting luke warm due to heat transfer......check the core for water flow Don.

You can bypass the a/c mix valve (at the firewall) by removing the long hose from that valve and the short hose from the heater core, then connecting the long hose to where you pulled the short hose off at the heater core.

I think if that valve is stuck, no water flows through the circuit, and the standing water acts as insulation.

Hold that thought. I was pretty sure I had done this until I read some of the related posts. Might need to verify the coolant path.

OK, looked at mine today...stand by my previous statement...bypass a/c valve using the connections closest to pass side of car.

Have you checked the SECONDARY valve located directly behind the center A/C outlet?

Your heater core is clogged with rust. You can probably get one from your local auto parts store from $35-$70. No big deal.

vintagetin said:

Your heater core is clogged with rust. You can probably get one from your local auto parts store from $35-$70. No big deal.

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i wish that were the case, mine is an AC car so there is more $$$ involved...no one around here has them and cant order them. i found some on fleabay....almost $300...

a/c box

Isnt it the same heater a/c box for 66-70 b-bodies?

if so .....i have what you need or can tell you where to get it.

I`m rebuilding on one right now. i have about 3 or 4 more and one with just heater also ready to go.

..heater core is copper/lead not a problem to rEpair on. I go futher and take out the internal valve$ / rubber hoses.

Replace them with some new copper tubes. Flar or size them. silver solder them in, hook it up to the garden hose and check it out myself.. Also just use one heater control valve from a 72 chrysler on up and put it under the hood with a longer cable. thats is where it should have been in the first place.

I have a rollbar in my car...you wouldnt want to mess with it again because there is only a few inches of clearance. I have to pull the dash to get it in and out.i have lot of pics they are just to big to put on here.

Uncle Don said:

i wish that were the case, mine is an AC car so there is more $$$ involved...no one around here has them and cant order them. i found some on fleabay....almost $300...

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Oh my gosh! I'm sorry to hear that.

bypass the heater control valve before you condemn the heater core. Your hoses will not get hot if no water is flowing through them. The control valve on mine is cable actuated maybe you can reach in there and manually open or close the valve. If it is leaking you will have to replace it anyway. If you still have no flow after you have bypassed it then your heater core is plugged. I have unplugged some by running water from a hose in the reverse direction through them. It works about 75% of the time on newer vehicles. I would really look at that heater control valve though. good luck.

A/C valve is circled in blue.

Heater core is circled in red.

Take hose with yellow stripe and attach to nipple marked with orange stripe.

This will bypass the A/C valve and let you test the heater core.

Pay attention if lots of nasty rust comes out of either place.

69 Runner said:

Have you checked the SECONDARY valve located directly behind the center A/C outlet?

Click to expand...

I repeat myself sometimes

crap im just now seeing the last two suggestions....i'll try that out and see what i get...but if the AC valve is bad don't i have to take all that under dash stuff out to change it out anyways? if so ill replace everything while im in there no?...thanks guys.

YY1 gave you a picture of the hoses to pull. The heater control, or water flow valve, is the one with the blue circle. Disconnect the hoses as stated, pull that unit off the firewall. When these go bad they will leak water inside your car as IF your heater core is bad. While the hoses are off, pull the other hoses off and flush the heater core like the other guys have said. Some MOPARS have vacumn operated controls located in-line with the heater hoses, some are cable operated, yours is located where YY1 put the blue line on the hose. For a TEMP fix, you can connect the hoses like YY1 stated, go to auto parts and buy a manual shutoff valve that you screw shut, cut one of the long hoses and insert the valve inline. When you want heat, you open the valve, when you don't, you close the valve. Again, TEMP fix and will get you out of a pinch. The little short u-shaped hose that runs between the two connections on the firewall makes an excellent connection for this valve and you don't have to ruin your new hoses.
The heater control module that I ask you to pull has gone bad on me many times, and leaks water all over my new carpet, so that is where I would look. The heater core is located under the hoses that YY1 marked with the red circle. Hope this helps

YY1 calls it an AC valve? you call it a heater control/water control valve? if this is bad could this cause my air condition not to work either? if so i hope its this and not my heater core...but in all fairness i can't beleive after 45 years that my heater core is still good lol...but i can cross my fingers.

ok after further investigation.....i did what you recommended above and went straight to my heater core, moved my hoses around to bypass my ac/heater valve whatever its called.... flushed out my heater core first....then hooked my hoses directly up....


WOW. do i have some heat....it'll run you out of that thing...im pretty tickled. now i just have to find one of these valves to replace it and get the air working soon...

i drove it around for about 2 hours today and no leaks..i cant beleive the core is still good. sweetness. thanks for your help guys, really appreciate it. i would have never tried that. now the question is where to find one....fun.