chevy G30 '93 coolant - which is which?

Hi All,

I am converting my 1993 Chevy G30 6.2 diesel mini school bus to run WVO (waste veg. oil)  I need to splice into the coolant system problem is I do not know which line is which.  I see two line going through the firewall, one on top of the other and I need to determine which is the line carrying coolant from the radiator to the engine, and and which returns the coolant to the radiator, anyone know off hand which is which?

Thanks,

Rif

I'm guessing your talking about the heater hoses for the heater core ??  If that's the case does one of those hoses run from the firewall back to the rad and connect just below the filler neck ?? That would be the return hose.

golfer,

Thanks for your responce. Yes that sounds right.  So let me just see if I am thinking correctly here.  Would the return hose carry the hottest liquid?  In other words I need to splice into the coolant system to provide hot coolant to circulate througha copper pipe heat exchanger, is the return hose the one I will want to tap?

Thanks again,

Rif

The return line is the cooler of the two.
 
Since there are two hoses going to the heater core one is the inlet ( or supply ) which supplies the hot coolant from the engine to the heater core. As the coolant passes through the heater core it gives up it's heat through conduction. This cooler antifreeze exits from the heater core through the outlet ( return ) hose and empties into the radiator to be cycled through the system again.

Thanks golfer, I think I got it!
 
Regards,
 
Rif

You're welcome.
 
I'm not sure as to which system you're using but here is a link with a basic diagram and explaination how to plumb in a heat exchanger : http://www.frybrid.com/forum/showthread.php?t=3189

golfer, that is a great and simple diagram.  I am using a Greasecar kit but the concept is consistant with the diagram.  Thanks again!

Rif