Most thermostats these days will stick wide open if the thermostat
truly saw a temp way above its control range.
Check and see if it's stuck open. The problem is, on most cars
the thermostat housing requires enough jostling that they usually break
free and close before you get a chance to look at it.
So you need to drop it in a pan of water on the stove and see if it
open/closes correctly.
What I have found (and heard here on the lists) the flow rates of the
water through the block vs what gets routed through the radiator
seems to be the root problem on a variety of Triumph engines.
I think this still comes back to the shrouded thermostat design that
was to facilitate routing water to the block and the bypass ckts.
4's 6''s 3', Spits, and the late MG 1500's all seem to have the same
general cooling issues. At low speeds the water flows fine....
(as long as your cooling system is relatively clean and the innards of
your block are not scaled or rusted.) At high speeds you get cavitation
and the water pressures, speeds and directions, don't readily lend
themselves to proper flow balance. Hence the shroud on the
thermostat as originally intended to be used on these engines.
The shroud effectively acts like a gate, helping to change flow paths
as it opened and closed. My 1980 Spit, bought brand new in '81
had a shrouded thermostat in it. Weird coincidence.....
just over the last two months while moving into my new
25'x25' garage with house attached (yippee!) I found some old photos
of me working on my 'pride and joy'. Sure enough... right in the
photo is a shrouded, and a non-shrouded 'replacement' thermostat
being installed.
Paul Tegler ptegler@gouldfo.com www.teglerizer.com
----- Original Message -----
From: "Ian Clough" <mc_ian@yahoo.com>
To: "triumph list" <triumphs@autox.team.net>
Sent: Thursday, August 15, 2002 8:11 AM
Subject: Overheated TR6... CRUNCH! GRIND! Sadness.
NoooooooO!
The recent heat wave we're experiencing here in Ottawa
has claimed another victim - my TR6. Sadness.
Driving home yesterday in 35 degre weather (I much
prefer when it's -35), I was at a red light and I
could smell something burning and thought "heh-heh,
some poor sucker's car is overheating". Almost that
same instance I saw steam coming from under my hood!
"Nooooooo! Why me Lord? Why ME??" Luckilly I was
almost home, so I took it really easy. I kept a close
eye on the oil pressure, but the temp gauge was off
the scale. Then it got worse, as I was turning onto
my street, as the revs were going doing to almost idle
I heard the distinct noise of grinding/breaking metal.
Okay, enough whining. The engine is now cool enough
to approach, where should I start? I really don't
want to start the engine not knowing what the grinding
sound was. My first stop will probably be the
thermostat, how can I tell if it was the root cause
and if it should be replaced? Then the engine itself,
what should I test first?
Ian Clough
Chernobyl-Red '75 TR6
HOTtawa, Canada
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