Log in

View Full Version : Heat & A/C question about water flow in heater system


Farrar
07-29-2011, 10:58 AM
Hi, folks.

Referencing this diagram,

2975
I can see that the water for the heater system flows out from the back of the water pump, through a big loop to the heater core and back, and then into the expansion tank via the small hose (Part #1) connected to the T-fitting (Part #5). That's where one short heater hose (Part #3) is attached.

My question is: what is the other heater hose (Part #3) connected to? It goes nowhere in the diagram. I assume it is also a "return line" since it connects to the same T-fitting, but where does it come from and what is it attached to?

Thanks,
Farrar
DMCMW Dave
07-29-2011, 11:09 AM
Back of the driver side cylinder head.
Farrar
07-29-2011, 11:11 AM
Back of the driver side cylinder head.

Thanks, Dave! So it is also a "return" hose?

Farrar
DMCMW Dave
07-29-2011, 11:57 AM
Actually I think you have the water flow backwards. It comes out of the head, through the valve, to the heater core, and returns to the back of the pump (suction side). This makes sure that the water to the heater is right off the hot part of the engine.
Morpheus
07-29-2011, 12:02 PM
Actually I think you have the water flow backwards. It comes out of the head, through the valve, to the heater core, and returns to the back of the pump (suction side). This makes sure that the water to the heater is right off the hot part of the engine.

That's what I was curious about... Also, when connecting hoses to the heater core itself, should it flow top to bottom or does it matter?
Farrar
07-29-2011, 12:05 PM
OK, so does that mean that the small hose at the top of the expansion tank is a "send" hose and the large hose on the bottom of the expansion tank is a "return" hose?

Farrar
DMCMW Dave
07-29-2011, 01:54 PM
OK, so does that mean that the small hose at the top of the expansion tank is a "send" hose and the large hose on the bottom of the expansion tank is a "return" hose?

Farrar

The small hose is a self-bleeder for the heater lines/engine.
The large hose is simply the fill/expansion hose for the system into the bottle. There is some circulation due to the bleeder dumping into the tank all the time.
Bitsyncmaster
07-29-2011, 02:03 PM
This reminds me of something on my list of things to do. I wanted to replace the vacuum shut off valve with an electrical one. But the cheap one I found requires a pressure differential (I think it was 2 PSI). I was just going to install it and see if it worked but there is an arrow showing the flow direction.

So the flow would be from the hose from the head to the valve?
content22207
07-29-2011, 03:54 PM
2982

Bill Robertson
#5939