Mark,
If you drive TR2 through TR4A, this is quite important. If you have a 6
cylinder Triumph or a Spit, this does not apply. The Stag has a special
stat as well, and the same principles apply, but the Stag stat uses a
blanking plate, not a skirt (sleeve).
The TR2-4A uses a thermostat housing that has a bypass hose to allow
coolant to circulate through the engine when the engine is cold and the
thermostat is closed. When the engine warms up, the stat opens, and now
your flow is supposed to go through the radiator. A sleeve on the original
Smith's skirted thermostat would move with the operation of the stat, and
shut off the opening to the bypass hose. Now a majority of the coolant will
flow through the radiator.
The absence of the blanking sleeve causes your radiator to not get a
majority of the coolant flow. The coolant will take the path of least
resistance, which is through the bypass hose, not the radiator. I have read
that cooling system operates at something like 30% efficiency with nothing
blocking the bypass hose! You will overheat quickly.
Since the original skirted thermostat is as scarce as hen's teeth, very few
folks are running original thermostats. The typical fix is to plug the
bypass hose totally, or put a restrictor in the hose that allows only a
fraction of the original flow. On my TR3B I put a washer with a 3/8 in hole
in the bypass hose, and had satisfactory results.
XK's Unlimited <www.xks.com> developed a great fix. Yes, they designed it
for an early Jaguar of some type, but it fits our TR's perfectly. They use
a modern 160 degree high flow thermostat and tack on a collar that acts
like the blanking sleeve. It works great. A lister (Hi Jack!) hounded Moss
when he had them on the phone for something, telling them they should look
into handling these XK Unlimited stats. Lo and behold, the new stats
appeared in my latest Moss catalog! From the picture, Moss is either buying
the stats from XK, or is using their idea.
I installed my XK stat and left the restrictor in my bypass hose. I
typically run from 170 to 180 at speed, and have seen the temp gauge as hot
as maybe 200 in traffic. YMMV.
No connection with XK's or Moss, yada yada... Just always happy to see
vendors manufacturing more parts to keep our cars going!
At 08:11 AM 3/1/99 -0800, Mark Gendron wrote:
>> From: Henry Frye <thefryes@iconn.net>
>> Subject: Re: SLEEVED THERMOSTATS !!!!!!!!!!!!!
>>
>> The 'stats Moss are selling are the ones we have talked about for some
>time
>> now. XK Unlimited makes them.
>
>I missed that discussion. What's the story with these thermostats?
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Henry Frye - thefryes@iconn.net - Connecticut, USA
Stag MkI Getting Sorted Out
TR3B Driver
TR250 X 3 The BIG Project - Will Be Worth the Wait
Homepage http://members.iconn.net/thefryes/
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