Jim---The suggestions previously offered are good ones. Don brought up
the vacuum retard, which is another cause of engines running warmer at
idle. Some mid-run models had the thermostatic switch in the top hose
that interrupted this retard action in the distributor.
We know at least three things happen when this interrupt goes into
effect:
The vacuum advances about 16 deg., which then speeds up the engine about
500 rpm. This in turn speeds up the waterpump. The effect we know to be
a coolant temperature reduction. (I do not know why the latest or last
TR6 did not have this feature)
Channeling air into the radiator by using a shroud in the front has to
be a good thing, but works primarily when the car is really motoring.
It also does a fair job of keeping sand and road debris out of the rest
of the engine bay.
When the radiator cap does not hold system pressure, the temp is very
lkely to be higher at road speed, as well as at idle.
It's necessary to burp any air out, after filling the system and before
installing the cap. Run the engine long enough to be sure the thermostat
is open. Absence of bubbles is what I look in this process.
WaterWetter is supposed to break down the coolant into smaller droplets,
making it easier to "wet" the surface and carry away more heat. This, as
well as modifying the waterpump design, should not be necessary for a
street-driven car.
It's also said that we shouldn't be too concerned when the temp needle
goes past the half-way point. At least not until it goes to the 3/4
mark. But my own confidence window starts to close well before this!
Dick
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