Re: Cooling system mods

[Bob Ducker <bducker@domain.elided>]

Ian Soady wrote:

> Nice to know someone else has the Stag / Commando combination - best
> of
> both worlds if you ask me!!! I think the Commando and the Stag share
> the
> common British feature (at least when we actually made things here
> rather than merely selling them) of getting the basic design right
> then
> rushing into production without sorting out the details.
>
> I have posted queries before about what seems to be air getting into
> the
> cooling system - the most common (and worrying) suggestion is of
> course
> head gaskets but as there are no other symptoms over the last 7000
> miles
> (since May) I'm discounting that (blissful ignorance perhaps). I think
>
> it's a slight leak from a hose (my favourite suspect is the overflow
> hose itself) which is sucking a bit of air back in as the system cools
>
> and potentially ends up with a < atmospheric internal pressure. I'd be
>
> interested to hear more about your device. Its very existence suggests
>
> that air frequently does get into cooling systems.

Greetings Ian...

As I remember reading about the "swirl can", the premise was that any
air in the cooling system would mix with the coolant within a short
period of time after starting the motor, to yield a foam  that reduces
the efficiency of the system. This assumes that the air is not trapped
in pockets that cannot easily mix with the coolant (such as seen in
mid-engined cars whose air bleeds are not carefully used when coolant is
refilled). It uses the vortex formed by the flow of coolant to separate
the air from the foam. As I recall, it is installed in series with the
water return line to the radiator and works in conjunction with a
separate pressurized surge tank, similar to the Stag's, but whose
connection to the cooling system is located right at the input to the
water pump. A line from the center of the swirl tank is connected to the
top of the surge tank, forming a loop that will replace the volume of
air removed from the system by the swirl can, with coolant from the
surge tank. I think the main concern was removal of air that might enter
from the water pump seal and other loose connections (such as you
mention!). If I ever get my Stag cooling correctly, I'll feel qualified
to give you more specific advice! Unfortunately, my recent wife has
convinced me to trade the Norton for a pedal powered bike, which I find
a lot more dangerous alternative in traffic than she thinks!

Robert Ducker
'73 Stag (original)
'73 Stag (chevy 350)