The V8 Owners Forum -

what are the two stub pipes that come out the back of the water pump, one is open and one is closed, what does the open one do?

They are both returns, as you say, one is blanked off on some variations.

One is the thermostat bypass (short pipe from inlet manifold), the other is heater return (long pipe that runs under the inlet manifold that emerges under the heater outlet at the rear of the manifold).

I presume you don't need the heater return.
I can't quite recall the configuration that has that stub blanked off.

Chris.

when i bought my hilux with rv8 engine, the long pipe was connected to the open stub pipe, i blanked the stub off and connected the long pipe to the short metal pipe coming off of thermostat housing, my truck wouldnt circulate the water today after putting it back together, could that be the reason why?

Could well be. What inlet manifold is it?

On the standard Range Rover one (as I recall), there should be the long pipe running under the manifold that connects to one of the stubs, and a stub underneath the thermostat housing that connects to the other stub. Do you not have both?

Chris.

it has the offenhauser 360, the long pipe was just connected to the left hand stub on pump as you look down on it, nothing on right hand side

I'm not sure I can visualise your actual arrangement but in general the principle is to ensure that the coolant can circulate thro the engine and heater matrix BEFORE the thermostat opens.

This prevents hot spots and allows for cabin heating during that period.

The thing is better explained, in context, on page 2 of the PDF available from here

http://www.vintagemodelairplane.com/pag ... ing01.html

If you actually needed the second outlet, is it possible to drill out the blanked off pipe?

cheers for info. Did you see on ignition forum that i got my rv8 going? timing was out 180.