Hi Dick,
I think you have the right feeling concerning the danger
fitting a thermostat in the top water-hose of a MMM-car.
As long as such a tubular thermostat is closed, there is hardly any
circulation (except maybe through a air-vent hole), and the nearly
boiling water reaches the thermostat much to late.
When I played with such a thing on my N-type, I first drilled some additional
2mm vent holes into the thermostat plate, to allow always a definite
amount of water circulating, but luckily later I found a K-type
works-thermostat.
Only when you use a thermostat which simultaneous opens and closes a by-pass,
as it was used on the works-thermostats (illustrated in the K-type manual),
than you avoid the risk of dangerous hot-spots in the exhaust-seat areas.
You hardly find thermostats with a by-pass, which fits our top hose.
And it also would be necessary to solder a by-pass connection
near the bottom-exit of the radiator, so that, until the thermostat opens,
the water only circulates through the engine.
The best way to handle the temperature, I think, is to fit a blind
in front of the radiator, which can be adjusted by a thin bicycle bowden-cable
from the driver.
When you drive in the mountains, the dessert or in the city-rush-hour,
you can't do without a fan between dynamo and radiator.
The car remains original, when a belt driven fan is used, as it was standard for
the F-type, as the same fan was also additional offered in the list for P's and
N's.
There are also nice, slim electric fans nowadays. ( I like the fans of the SPAL
company)
Gerhard Maier
PS.: Not a few MMM-people also drive a MGA, Midget or MGB,
and for those cars it is worth to look for a old-type thermostat, which still
has the brass-ring, which moves up and down when the thermostat works,
and this ring opens and closes the by-pass.
Modern thermostats, without ring, all the time allow the water to find the
easier way through the by-pass as instead through the radiator,
and so cooling efficiency is not 100% as it could be.
-----Original Message-----
From: owner-mg-mmm@autox.team.net [mailto:owner-mg-mmm@autox.team.net]On
Behalf Of Gill And Dick Morbey
Sent: Saturday, January 04, 2003 12:49 AM
To: mg-mmm@autox.team.net
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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