On Fri, 8 Jan 2021 11:42:12 +1100, Xeno wrote:
> You need to appreciate the two (2) primary functions of the thermostat;
> it gives a faster warmup and maintains a *minimum* operating
> temperature. What the thermostat does, therefore, is totally dependent
> upon the capacity (efficiency) of the cooling system. That means, if the
> cooling system capacity is greater than the needs of the engine, even
> under maximum power, maximum load situations, the thermostat will
> continue to *restrict* coolant flow. That means it will have to either
> *cycle* or, alternatively, maintain an *intermediate flow restriction*
> position.
Hi Xeno,
Thanks for explaining that the thermostat is, in some cases, _restricting_
flow most of the time, even when, from the outside looking inward, we'd
consider the engine well warmed up (e.g., after five or ten minutes).
> remove the thermostat and you have *no control* over the minimum
> operating temperature. All cooling systems are (or should be) designed
> to provide *excess* cooling capacity. That provides some leeway as the
> cooling system progressively degrades through blockage and buildup over
> time.
OK. It makes sense that if the thermostat can be fully open, but if it
usually isn't fully open, that it can regulate the _minimum_ engine temp.
>> At least that was way back when...
>
> Beg to differ, it never was like that. The engine would run *cooler*. In
> fact, even a working and fully open thermostat provides some *extra*
> restriction over an absent thermostat.
Understood and agreed.
o The thermostat itself, is a restriction, even when fully open.
> What's more, some thermostats
> provide a facility to block off a bypass passage once the engine has
> warmed up. Removal of the thermostat on engines so designed will cause
> *overheating* with the thermostat removal since the bypass flow is not
> being blocked off as it should be thereby preventing a percentage of the
> coolant circulating through the radiator.
> https://www.are.com.au/feat/techt/thermostat.htm
Ah. I remotely remember learning something about a "bypass" long long ago.
Thanks for your patient explanation of my misconceptions.