Fan clutch working?

[FGN59]

Although I live in southern France, we seldom get really hot weather (above 35°C-95°F), my car does not have AC, and I have so far never driven it in city traffic, stop and go etc. in such conditions.

What I experience is actually that the engine almost never really gets above its minimum operating t° (85°C?) (maybe it happened once, for a few minutes, after a longish drive on a highway in warm weather as the car was suddenly moving in slow traffic). In fact, the gauge is nearly always below the horizontal, which drove me to check the engine temperature with an infrared gun, during the heating up phase and after a little bit of driving, at the radiator entrance, water pump, engine block (right and left side, front and back). I came away reassured that the temperature was high enough, just barely, in almost all circumstances. The gauge may be off a little bit, but that’s not the reason for my inquiry.

The question I have is how does one check that the fan clutch is working as it should? I have a feeling that the one on my car is always engaged, but I don’t really know how to test it. I’ve read (here and elsewhere) about the newspaper test, but I don’t know what to do with the newspaper except read it  ?

[WRe]

Hi,
the visco fan works hydraulically and depending on the temperature and is controlled by a bimetal spring.
When the engine is cold, the fan should turn with no play and with noticeable resistance.
When the engine is running cold (after start), the fan first runs with it (audible blowing), then it only runs at low speed without any power flow.
If the engine temperature rises above 90°C degrees, the bimetal reacts and opens the clutch's oil supply via a pressure pin.
The fan gets power flow again and runs at approx. 3500 rpm. The function can now be heard distinctly and felt again. If you don't trust your ears you can fold a newspaper and try to bring it between the blades. If you can stop the fan your clutch doesn't work properly or the temperature is not high enough.
Here you cann see and hear how it works: https://kfz-tech.de/Biblio/Kuehlung/Viskoluefter.htm .
...WRe

[stickandrudderman]

You should never physically stop the fan whilst the engine is running. It proves nothing and presents serious risk of injury.
In any case a faulty viscous coupling will only present symptoms of overheating.
Failure to achieve running temperature is most likely to be caused by a thermostat failure.

[FGN59]

Thank you gentlemen for your answers. In other words, the fan clutch can fail to engage, but it cannot be ‘always engaged’?

The fact is I tried stopping or slowing the fan with a rolled up newspaper while the engine was cold, and could never get it to slow or stop, and have on the other hand never heard it run at high speed as in the video either. But then if my engine never overheats, that’s probably normal.

I will investigate the thermostat. Thanks again for your advice.

[stickandrudderman]

In other words, the fan clutch can fail to engage, but it cannot be ‘always engaged’?

Correct.
A lot of people confuse a "viscous coupling" with an "electro-magnetic clutch".
The latter is literally switched on and off by a thermo-switch and will indeed free-wheel until coolant temp reaches the prescribed limit whereupon it will suddenly fully engage. 113s were never fitted with an electro-magnetic clutch.