RE: Cooling system mods

[ggrunwald@domain.elided]

I am going to put in my two Bobs worth on this.  The following description
comes from my study of the Stag cooling system and if anyone has other
opinions I would be happy to hear them as it all helps build my knowledge.

My understanding is that the disk on the back of the correct thermostat
blocks the inlet manifold bypass port when the vehicle is up to operating
temperature.  The theory is that as the car warms up the thermostat is
closed and the bypass port is open.  This allows the coolant to circulate
around the engine via the water pump and inlet manifold.  This gets the
inlet manifold up to temperature quicker and therefore leads to proper fuel
atomisation and vapour flow, leading to smoother running sooner.  Once the
vehicle is up to temperature the thermostat regulates the coolant flow and
allows some coolant to continue to flow through the manifold, with of
course the majority through the radiator, particularly when the thermostat
is fully open.  If the thermostat does not have the bypass blocking disk it
means that some coolant can continue to circulate via the manifold,
bypassing the radiator, when the thermostat is open  This can lead to
overheating which is not good for a Stag.


Guy Grunwald




bducker@domain.elided on 05/11/97 07:09:54 AM

To:   Brian.Tink@domain.elided, owner-stag@domain.elided
cc:    (bcc: Guy Grunwald/Network/energyAustralia/AU)
Subject:  RE: Cooling system mods




At 10:02 AM 10/24/97 +1000, Brian.Tink@domain.elided wrote:
>What's this air conditioning stuff??
>
>My cars come with an air-con system called  "ALL-X"
>
>           ALL  = all windows down and in the case of the stag top off,
and
>            X   relates to the speed in either MPH or KPH
>
>keep staggering
>
>Brian
> <snip>
Yeah, I probably won't use mine very much either, but I want it to work
anyway (words to live by!).
But getting back to overheating, another thought I had relates to the disk
on the back of the mark II thermostat. After thinking about it, it seems to
me that this disk should contact the back of the housing when the
thermostat is installed, so that the spring pressure will only allow
coolant flow through the bypass passage when there is high pressure (and
which will increase as it opens). As I recall, mine did not install under
spring pressure. If you do the math, a 1/2 open thermostat is only open
about 1/8 inch, so it seems likely that the disk must be installed closer
than that, at least. My version of the shop manual doesn't mention anything
about this, but they could be assuming that a correctly manufactured part
(and correctly machined housing) is being used! Does anyone have any better
information?
Robert Ducker