[TR] TR4A - Fan temperature threshold question

[Chris Kantarjiev]

> What temperature is too hot for the TR4A engine?
> I am looking to install a thermostatic switch for the electric fan in the near
> future, but don't have any appreciation on the on/off temperatures to look
> for.
>
> I found an in-line switch from Derale that turns on at 180, and off at 165,
> but don't know if those thresholds would be appropriate.

It totally depends on where you measure it.

After years of screwing around with aftermarket electric fan installations, I 
have come to appreciate the wisdom of the setup on most Italian and some German 
cars: put the sensor at or near the bottom of the radiator, not the top.

What you're trying to determine, really, is if there is enough air moving 
through the radiator core to lower the coolant temperature. If the temperature 
at the bottom of the core is "low enough", you know that the radiator is doing 
its job. If it is "too high", then you want to provide extra air by turning on 
the fan.

I usually use an adjustable, but you can use a fixed temperature sensor and 
move the mounting position up and down to make the temp gauge needle do what 
you want. The 4A's thermostat will open somewhere around 180; that's the point 
at which the designers thought the engine was getting too warm and they wanted 
to cool it down. As long as the water exiting the radiator is reasonably below 
that, the job is getting done.

I'd probably start by mounting the sensor about 1/3 of the way from the bottom 
- and plan to move it at least once.

chris