As I think I already mentioned , I am driving a TR8 sans thermostat, and
last weekend drove 200 miles in 93 degree heat at 75 freeway, and some stop
and go and temp was exactly the same as with the thermostat. So whatever
the theories, in my case no diff.
----------
From: Michael D. Porter <mdporter@rt66.com>
To: Bruce T. Clough <cloughbt@batman.flight.wpafb.af.mil>
Cc: triumphs@autox.team.net
Subject: Re: thermostat
Date: Wednesday, July 02, 1997 1:56 AM
Bruce T. Clough wrote:
>
> Mike, I don't mean to pick on you:
>
> >... Even when fully open, the thermostat provides
> >some restriction to flow--this is necessary to allow coolant circulating
> >through the radiator enough time to dissipate heat. Without the
> >thermostat, coolant may pass through the radiator too quickly for
> >adequate heat exchange...
>
> ...but this falicy has been posted here too many times. One more time,
> please people, repeat after me:
>
> EVEN THOUGH THE COOLANT RUNS THROUGH THE RADIATOR QUICKER, IT RUNS
THROUGH
> THE RADIATOR MORE OFTEN. THE "MORE OFTEN" PART MORE THAN MAKES UP FOR
THE
> "THROUGH THE RADIATOR QUICKER" PART, CAUSING A CAR WITHOUT A THERMOSTAT
TO
> RUN COLD.
Sorry not to have made my point accurately. Should not have mentioned
radiator--but there is a point to having a restriction in the cooling
system at the place the thermostat is located. The water pump forces
water into the block, and it goes out the thermostat opening to the
radiator inlet. Removing the thermostat does increase the flow rate, but
without the restriction it creates, also reduces the effective coolant
pressure in the block. The lower the effective pressure, the higher the
rate of nucleate boiling in the engine water jackets when the engine is
fully warm and under load, which reduces the surface area from which
heat can be taken by liquid coolant.
As far as a car without any restriction at that point running cold, this
is only true when the heat rejection rate of the radiator is higher than
the waste heat introduced into the coolant, either because of the
ambient temperature, or the rate of airflow through the radiator, simply
because the temperature of the jacketing does not get high enough to
induce nucleate boiling. Put that same engine to pulling a hill on a 100
deg. F day, and it will very likely overheat. In one sense, this is
somewhat analogous to installing a radiator cap of a lower pressure
rating than is optimal.
As one other person suggested, overheating can and does occur (my
experience with my TR4 was the same as mentioned)--and it's been true
for a number of engines in my experience in the past, and I think for
the current one. <g>
> Sorry to keep repeating this stuff, but we need to understand how things
> really work if we are to fix them.
And that is how things really work. Now, is someone going to tell me
that nucleate boiling is a figment of the imagination? <g>
Cheers.
--
My other Triumph runs, but....
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