Radiator overflow hose/nipple - what's it for?

Huw Powell human747 at attbi.com
Wed Jul 24 01:25:41 EDT 2002

> > For one thing, when the coolant in the engine and radiator heat up and
> expand,
> >coolant can flow from the radiator into the translucent overflow tank and
> >compress the air in that tank. AND, excess pressure in the radiator beyond
> >the 17-22 lb limit can be directly relieved by the valve in the pressure
> >cap on the expansion tank.
> But ... there is another hose connecting between the bottom of the overflow
> tank and the radiator that would continue to serve this purpose.  Wouldn't
> it?  This hose and a bleed screw in top of the radiator seems to be
> sufficient for the 4kq.  I think the overflow hose really only serves to
> let escape from the system, that's why it's at the highest spot on the
> radiator.  It's only advantage over the 4kq is that no human needs to
> remember to open the vent.

the 4kq has the little top hose as well.  it is a circuit.  coolant
flows into the exp. tank via the little hose, and drains back into the
radiator via the larger, lower hose.  Whatever you do, don't block it.

Gases can build up in the radiator in "normal use", that little hose is
their way back to where they belong, in the expansion tank.

Huw Powell



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