Cooling system query

[Wossname]

Relating to our old (Talbot) camper van really…

When the engine warms up and the thermostat opens, does it just stay open (fully) or does it adjust itself to control engine temp? I’m having a discussion on another site about this; my understanding is that temp control is governed by the fan/fans cutting in and out based on a rad temp sensor, and the stat is fully open once the engine is up to temp. Right/wrong? Do stats have “ midway” positions iyswim? TIA….

[dern]

They have an operating range of generally about 10 degrees between fully closed or fully open. That should be set to be around the operating temperature of the engine so they regulate by adjusting between fully closed and fully open with all the states in between. If your engine operates above the maximum temperature though they'll stay open but that's not where you want to be.

The fans are there to bring down the temperature by 'force' if you haven't got enough airflow to dissipate heat without them.

[Mr. Dazzle]

They typically have a middle position. Otherwise you wouldn't be able to drive with a consistent engine temp when outside temp can conceivably cover a range 80°C wide. Although TBF that's much more of a concern on modern global vehicles.

My car uses an electric variable speed water pump instead cause its marginally more fuel efficient Saves using the engine to drive a pump to work against a valve which is closed alot of the time.

[Le_Fromage_Grande]

Old ones are open or closed, new ones are more variable

[Wossname]

This is an “old” one, so not sure that @dern is right.

[Mr. Dazzle]

It's unlikely to be controlled solely off the fans though, because the fans are actually pretty feeble in relative terms. Even a big fan is not gonna shove air in at anything like the rate just driving along at 40mph does. The motion (or not) of the vehicle generally swamps anything the fans might do.

Which is why you have a thermostat...

[Taipan]

On older vehicles, the coolant temp is determined by the thermostat which works within a certain temp range. The electric fans provide assistance when the thermostat cant keep it controlled, which is typically around town or under continued heavy load.

[dern]

Put it in a pan of water with a thermometer, you'll soon find out.

[Yambo]

I always thought they were called a thermostat instead of a switch for a pretty good reason.

As Dern has said, stick it in a pan of boiling water and watch what it does while controlling the heat.

[Yorick]

The old Yamahas was simply open or shut. Mine broke and engine overheated. Blew up

[Mr. Dazzle]

stick it in a pan of boiling water and watch what it does while controlling the heat.

It's thermostats all the way down!

[Felix]

stick it in a pan of boiling water and watch what it does while controlling the heat.

It's thermostats all the way down!

You having bother? The one in my Maxus is stuck open making the engine run cooler what can increase MPG. It is also fixed in a housing making a mew one bloody expensive. I found out the pipe out from the thermostat is the same diameter as an old Renault 5 thermostat so stuffed it in and its been great since. Engine is smoother and i get more heat from the heater.