64 - No heat

[chris1044]

I've been lurking for sometime...finally picked up a 64. It's a 20 footer, which means I'm not afraid to use it right up to the point of salt on the roads here in MI.

I've been having some issues with the heat - as in there is none. The truck has the thrift heater in it, engine is a 350 with a high performance Edelbrock water pump - for those not familiar, it's the style that has NO provisions on it for any heater hose. As a result, I've got one hose that feeds the core from the port on the intake manifold, and another that is plumbed just up stream of the thermostat housing - between the engine and radiator inlet. The blower/blend door works fine and I get plenty of airflow over the core then into the cab.

I don't seem to be getting any coolant flow through the core, so today I pulled the hoses and blew through it via the air compressor. This is where my questions starts:

1) Does it really matter which hose is in and out? One's a 5/8" ID and the other a 3/4" - right now I believe the 3/4" is the inlet and the 5/8" the outlet.

2) My core had a plastic restriction orifice in the smaller 5/8" tube. Why? I pulled it in hopes of getting increased flow with it out....no success.

After fully bleeding the air from the system today, I'm once again left with a semi-warm hose from the intake and a cold one going from the core return. I know the core isn't plugged, so there's got to be too much head to flow through it on the return side.

I'm fairly sure I can plug the T-Stat housing port and just dump the core return back into the top of the radiator as there's another plug there. But why would there be a restriction valve in the core? Other suggestions?

[davbowen]

i think you are out of luck with that pump. but heres what found real quick

http://67-72chevytrucks.com/vboard/s...d.php?t=559186

[PGSigns]

Show us a pic of how it is plumbed. From the sounds of it is not correct.
Jimmy

[LVPhotos]

Here is my old layout. Top hose to pump, Lower hose to intake.



http://67-72chevytrucks.com/vboard/s...d.php?t=562723

[awbrown]

a picture would be great ....,but yes if you have one that comes from the intake (not the top of the t-stat housing ) then yes you can plumb it to the radiator, if the problem still exists and you can see flow in the radiator ,or somehow can prove you have flow through the core, then the core should be replaced.. both hoses should be hot ,if they are not then you wont get any heat ... Got that picture??

[PGSigns]

The heater water to the core on a 350 should come out of the pump and return to the intake before the thermostat housing. If you try and run it out of the top of the intake and to the radiator you have bypassed the thermostat with a large volume of water and the engine will not make any heat. The Edelbrock pumps should have the hole for the fitting in it. Out from the pump with the 3/4" hose and back to the top of the intake with the 5/8" hose.
Jimmy

[Scot_Douglas]

I'd call the previous owner and tell him what a dumbass he is.

<edit>
I just looked through all of my photos and don't have one of the setup. I originally went with this suggestion. Since I never put the heater box in my 66, I never realized it wasn't working.

</edit>

[chris1044]

Originally Posted by Scot_Douglas

I'd call the previous owner and tell him what a dumbass he is.

</edit>

This made me ...

Of all the things I should be playing with on this truck - like lowering it or finding a trans that will live behind this mill, I'm worried about heat so I can defrost the windows when my mutt's are cruising with me!

I'll try to upload a pic in the AM - I'm on my phone replying to this. A few things:

1. Current plumbing: Out of the intake manifold port @ the front, to the core. From the core outlet, back to the T-stat housing on the RADIATOR side of the T-stat. The thermostat housing has a second NPT port in it that is for?? The first port has a temp thermistor, the second has got a male nipple fitting to which the outlet of the core is attached to. LV - Can you confirm your intake outlet is going to the smaller tube on your core?
2. Engine has a T-stat in it, and I can 100% confirm the coolant gets somewhere in the neighborhood of 190*F - verified by sticking a thermocouple into the radiator after a drive. T-stat isn't stuck open, and doesn't stick closed
3. Flow in the radiator - very plentiful! This pump moves some water!
4. My radiator has an unused port on the top tank, passenger side - looks like it's 1/2" NPT or so

So, here are my thoughts after reading the responses:

1. I need to find out if the port on the intake (front runner, passenger side) is in fact pressurized. If it is, I should have flow when the T-stat is closed for sure. Heat would suffer once it opens as the coolant will take the path of least resistance back to the radiator
2. I have zero clue why that restriction was in the core....Can anyone confirm this isn't stock? (pics in the AM) It was in the smaller tube if that helps.
3. If I take the outlet of the core from the radiator side of the T-stat housing to the top of the radiator, I'll have less head on it than when it's hooked to the T-stat...however it's essentially in the same place
4. If I *really* wanted, I could solve all of this by drilling/tapping the water pump inlet for a fitting. Mine 110% does not have one.

It does look like I should have the hose from the intake going to the smaller 5/8" pipe on the core, and I'm fairly sure it's reversed...but the core should still get hot.

When I get more time I'll start a build thread...I got an excellent starting post from Scot!

[jtrichard]

Is there a "T" Stat in the engine? is the engine getting up to a decent temp like 190? if you pull the outlet hose (plug where it was hooked) and start the truck how much flow you getting?

[ACK]

Once you have the plumbing figured out and if you're still not getting heat, it's possible a previous owner had a leaky radiator and added Bar's Leaks or similar additive. The stuff clogs the heater core and even if you flush it out, it still can prevent it from getting nice and hot. A garden hose fits over the heater core inlet really nice, if big chunks of crud start shooting out the other side after running it a few minutes, there ya' go.

[Scot_Douglas]

Originally Posted by ACK

Once you have the plumbing figured out and if you're still not getting heat, it's possible a previous owner had a leaky radiator and added Bar's Leaks or similar additive. The stuff clogs the heater core and even if you flush it out, it still can prevent it from getting nice and hot. A garden hose fits over the heater core inlet really nice, if big chunks of crud start shooting out the other side after running it a few minutes, there ya' go.

I'm the PO: While I cannot confirm if the cooling system ever had stop-leak added, I can say that when this little gem was in the truck...



...there was plenty of heat. I'm sure it is because I was too cheap to put a pump on it with a nipple. I bought the serpentine setup complete with the high flow edelbrock pump for less that the price of a new water pump.

[PGSigns]

If you don't run it from the pump and to the intake you will never get much heat. The reason to get the water from the correct place on the pump is flow. Has nothing to do with pressure as the entire system is under the same pressure. The way the hole in the pump is setup bleeds a lot of flow off the impeller. I would put a pump on the engine set up for the fitting. 3/4 hose from pump to the core 5/8 to the intake and all will be good if core is good.
Jimmy

[chris1044]

Originally Posted by PGSigns

Has nothing to do with pressure as the entire system is under the same pressure.
Jimmy

This is a common misconception. Anytime you have coolant flow through an orifice you'll get some type of pressure fluctuation. Engineer's try to minimize pressure drops in the system for obvious reasons, but rarely during operation is the pressure uniform throughout. A couple decent reads on this... Here and Here.

Here are some pics...

The restriction that was in the core:


Just so I'm clear, the port on the intake manifold usually goes to the core inlet, and the outlet of the core goes to the inlet of the pump, correct? Worst come to worst, I pull the pump and drill/tap the inlet for a fitting.


Chris

[PGSigns]

Flow out of the pump to the core. Out of the core to the intake. I fully understand pressure and flow. I do it for a living. Also been working on these trucks for close to 40 years. Got my first one in 1975. Problem with drilling the pump you have is you need to remove the impeller to drill the hole. Your belt setup looks like it is setup for the reverse rotation pump so be careful of what pump you put on it.
Jimmy

[chevy_mike]

Well looking at your picture, you're not really going to get any flow hooked up that way. Both ports (the one in the intake and the one in the t-stat housing) are both flowing back to the radiator. They will give little if any flow into the heater core.

You must have the heater input hose hooked to the water pump. It looks like your water pump was used on some application that likely took the flow to the heater core at another location in the block.

Since I am setting up the same belt setup, I used a water pump from a '92 Camaro, which has the correct output port on the top of the water pump. Here is a pic of the setup.



I like this water pump as it direct the heater hose in the direction of the heater core, so I can route hoses cleanly. This is what you need and then use the return port in your intake and block off the t-stat port (or use if for your temp sending unit).