Steve,

        You're right, it's not positive, no centrifigal pump is. But they will move a lot of water when there's no restriction (like the Thermostat). The problem with that is if you force too much water at too high a velocity through the radiator it won't have enough time to transfer the heat. It really sounds to me like this is a case of an air lock or a defective pump (loose-Impeller, full of rust?) or a plugged up water jacket.

         Stue, it's an actual pump. They will generate pressure when spun hard enough!

Frank/Rebop

Bristol, In ( by Elkhart) 

Centrifugal pump feeds into front of block - around galleries for the cylinders - then into the heads at rear - then forward to the crossover passage feeding your thermosatat housing. That passage is right across the front of the intake manifold - there isn't one at the back of it. Typical engine gains about 10° of water temp between the rear of the head and the thermostat housing.

Bypass port under thermostat is a straight shot back to pump - so is port for heater return hose. They both short circuit system and pass heat around the radiator when open. Heater line goes "dead" when heater is off - bypass provides rapid warm-up function - but is a dead loss (5/8 garden hose sized path around the radiator!) after that. It provides a coolant path when the thermostat is closed at start-up. 

The pump isn't "positive displacement" at all - any restriction at all tries to defeat it. It also turns pretty slowly compared with modern engines - these rascals idle down to 550 no worries. One of the best reasons to get a very free flowing big poppet thermostat.

 
 Steve Metzger       Tucson, Arizona

Stuey, I believe the water pump is actually a true centrifugal pump.  But you're brining up a good point.  How does the colant path go?   I  was just looking at some pictures of a y-block water pump at rockauto.com  and it appears that it takes water from the lower hose or the by-pass hose and then pumps it one of two places. 

1) into the block (the pump impeller sits inside the block and send water through the water passages??) and back to the radiator through the upper hose or to the water pump through the bypass hose.

2) to the heater core and into the manifold??

These are my guesses so I hope someone can confirm.  To summarize the pump has two entrance points and two exit points. The entrance points are the lower radiator hose or the bypass hose.  And the two exit points are either through the engine block or through the heater core?

So in theory if I plugged the bypass and the heater lines, all the water would flow from the lower radiator hose through the engine block and back to the radiator through the upper radiator hose.

Is this right?

Nate - Madison, Wisconsin

 

56 Ford Customline Sedan

 

hi there

i'm hoping someone with more experience than me will jump in here

is the water "pump" actually a pump or does it just assist the natural flow (thermo syphonic)

you may be misleading your self and the problem is the green gloop

waiting to be shot down in flames   and to learn something

stuey

Thanks for the ideas Green.  When I filled the car up I loosened the thermostat housing to let the air out until water started coming out, then tightened it back down so there shouldn't have been too much air in the engine.

The bypass hose is new so it shouldn't have stuff in it, but I didn't explore the points that connect it.  I will pull that little bypass hose back off and check that the connections are free and clear.

The other thing I noticed that I forgot to mention is that the hose I'm using to bypass the heater core (running from manifold right to the pump) never warmed up!  I assumed warm water would be flowing through that thing (it is the heater supply line!) but I kept grabbing it and it was cold, even with the water coming out of the engine was 200F.  I suppse that 90degree elbow on the manifold could still be plugged inside?

Nate - Madison, Wisconsin

 

56 Ford Customline Sedan

 

I suppose the short front bypass hose looks (inside) just like that heater hose? Those burps are from air locks in the engine - big bubbles that have to get passed out of there - especially out of the waterpump housing. The thermostat is trying to regulate too I'd say.

The bypass - and the two points that feed it need to be cleared of gunk so air will pass.

The heater line that returns to the pump needs plugged (for now).

The heater line behind the thermostat housing needs an open pipe elbow, hose attached and a manual valve. Open the valve - and with the engine off slowly fill the engine and rad - to get all of the air out that you can. When it will run nicely out the top of the intake manifild - close the valve. Then try your test again.

 
 Steve Metzger       Tucson, Arizona

So I'm no longer confident that my water pump is pumping any water.  This morning I was flushing the vinegar out of my cooling system by extending the upper radiator hose out over the front of the car (using shop vac extension, see below) and sticking a running garden hose into my radiator filler.  Here is the sequence of what happened.

1) I started the car and let her warm up to temp WITHOUT running the garden hose into radiator yet.  I wanted to see what happened when the thermostat opened. 

2) When thermostat opened, water kind of "burped" out of the upper hose, it didn't run out smoothly.  It would erupt like a volcano, spew some water, then nothing, then erupt again, then nothing.  More like it was vomiting (coming out from boiling or pressure)

2) I let it "burp" out for 30 seconds or so, then I put the hose in the radiator filler.  Very quickl after putting the hose in the radiator, water started running smoothly out of the upper radiator hose.

After going through this sequence a few times, it ocurred to me that the smooth running water out of my upper radiator hose seemed to coincide with me putting the garden hose in the radiator filler.  The thermostat was in place during this, so I'm dicounting the time when the thermostat was closed.

After playing around with this for a while I become convinced the only reason water was ever running out of the upper radiator hose was becuase I was adding water in the radiator and the upper hose outlet was slightly lower than the radiator filler.  To test this theory, I put a block of wood under the upper radiator hose extension (shop vac attachment) so that the outlet was higher than the radiator filler neck.  I then let the car warm up again without the garden hose in the radiator and waited to see what would happen when the thermostat opened.  All it did was the "burping/vomiting" thing again, it never supplied a steady stream of water unless I put the hose back into the top of the radiator.

Should the water pump have been able to create a steady stream of water out of the upper radiator hose (at least for a moment) without me adding water to the radiator?

Is there some other way to test if the wtaer pump is working?   I notice my pump is stamped with "reman" on it in yellow ink.

Nate - Madison, Wisconsin

 

56 Ford Customline Sedan