I have been using a standard thermostat on my PA and it works fine. I drilled
holes in the thermostat frame to allow some flow.
Jerry
Neil wrote:
> Not sure about specific MMM issues, but generally there should be a bypass
> of some sort to allow some flow even when the thermostat is shut, to prevent
> hotspots occuring before the thermostat opens. In the A-Series engine
> (Spridgets etc) there was a small hose under the water pump that did this,
> the later (A+) engines did not have this bypass hose but had heaters that
> always took some flow. My (Turbocharged) Sprite has this set-up and all is
> well.
> One other issue with putting the thermostat in the hose is it might not
> recieve any heat to open it, even if the water in the engine is already too
> hot, unless there is some flow of water past it. In Vizards A-Series tuning
> book he suggests drilling a couple of holes in the thermostat base plate to
> provide the bypass flow path - maybe this would be worthwhile for the MMM
> application.
> My other thought is regarding non-pumped systems. Would the thermostst in
> the top hose give too much restriction for thermosyphoning to be effective
> enough?
>
> Neil
> PA1218
> '68 CGT, '73 Midget, '71 Sprite Turbo
>
> ----- Original Message -----
> From: "Gill And Dick Morbey" <gd.morbey@virgin.net>
> To: <mg-mmm@autox.team.net>
> Sent: Friday, January 03, 2003 11:49 PM
> Subject: Thermostat in PA cooling system. Worth the effort?
>
> > Dear All,
> >
> > (The following is a repeat of a message I tried to circulate recently - it
> > appeared to go into a black cyber hole!)
> >
> > The excellent Triple M Bulletin bulletin, edited by Philip Bayne-Powell,
> is a
> > fascinating and regular publication available to Triple M register
> members.
> >
> > In the latest one I spotted a tip which may be of help to us Brits at this
> > time of year - fit a thermostat into the top hose. Halfords evidently
> sell
> > one that is a nice snug fit. It is their part no. HTS 610.
> >
> > This set me wondering.
> >
> > The Halfords thermostat is of a type which remains totally closed until
> the
> > temperature rises to 83 degrees C, whereupon it opens. It has no bleed
> hole
> > or bypass valve.
> >
> > My P type has a water pump fitted, which circulates water away from the
> botom
> > of the radiator and assists its flow through the hot part of the engine
> until
> > it reaches the rad header tank. In normal conditions this allows the
> engine
> > to run cool - far too cool, I suspect - 60 degrees in Winter and not much
> > above 75 degrees in Summer. Blanking the bottom of the rad has helped to
> get
> > a bit of extra heat into the system, but not much!
> >
> > So, if I fit a thermostat, I reckon that the water will heat up nicely,
> but
> > will have nowhere to go until the temperature reaches 83 degrees and the
> > thermo valve opens. So instead of being over-cooled, it's likely that the
> > beastie may become over-heated - es[ecialy at the back end of the cylinder
> > head !
> >
> > What opinions do MMM folks have on this subject. And would it be any
> > different for cars that do not have a water pump, and simply rely on
> > thermo-syphoning to move the water around?
> >
> > Best wishes to all.
> > Dick Morbey
> > PA 0743
>
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