Does a 126 Bis need its fan at tickover?

[elanman99]

I have been getting my watercooled 126 bis ready for the road. It had been stood for a couple of year after being resprayed before my ownership so I am not accustomed to normal operation.

The cooling system is fully functional but the radiator fan never runs. I have left it ticking over for 50 minutes and the engine does not overheat, in fact it never reaches the temperature of the first stage of the thermostatic switch.

I am wondering if this normal?

Because at tickover the engine is not really doing any work maybe it just reaches equilibrium and the block just radiates its heat into the surrounding air. Until its road legal I cannot really make the engine work hard hence this enquiry.

Ian

[mintex]

Hi
Mine will kick in if i leave it ticking over long enough, normally only on the first slower speed but it does kick in.
Has the thermostat been taken out of yours or is it stuck open?

[Xylaquin]

According to the workshop manual the radiator doesn't turn on until the coolant reaches 96C, and even then it doesn't go to full speed until the coolant further reaches 101C.

Not a clever design in my opinion.

The previous owner of my BIS modified the cooling system so that it's manually controlled by a little switch to the right of my dashboard cluster. So whenever I see the temp gauge getting close to the mid point/95-100C I simply flip the switch, the fan comes on at full speed, and after about 20 seconds it's back down at 80C. I then flip the switch back off and continue driving.

So yes it's normal for the radiator fan not to turn on. Sometimes I don't need to turn it on at all, particularly when it's cold outside.

[elanman99]

Thanks guys, you've set my mind at rest.

Since I asked the question I have been trawling through posts on this forum and see the temperature topic has been discussed several times. I have not checked the coolant thermostat yet but will give the car some daily use first to shakedown any other potential problems.

Ian

[mintex]

According to the workshop manual the radiator doesn't turn on until the coolant reaches 96C, and even then it doesn't go to full speed until the coolant further reaches 101C.

Mine comes on at the first slower speed when the gauge is between half and quarter then comes on full just before half way   

[Gadge]

Unfortunately the little tabs that the spade connectors conect too on the little coil have long dissapeared so I only have one speed this kicks in when the needle is 2 marks away from the red so I'm presuming that is around 95 degrees

[Xylaquin]

Since the furthest left mark is 70, I reasoned that the furtherest right part of the scale (ie the right-hand side of the red section) was 130.

Based on this, each increment would seem to be 5C

[Amateb8]

The fan on my 126 Bis does not switch on until the indicator reaches almost half way. When it does switch on, it seems to run for about 30 seconds, and the indicator comes down a little. When in comes up to the aforementioned, another 30 seconds, so on and so forth.

It is important that the fan works. As a precaution, I get the radiator flushed at least once every two years (500+ miles a year). I use a coolant/anti freeze mix with distilled water. Regular oil change help the engine cool down process.

[Lloyd74]

On the radiator flush thread I flush mine with power flushing fluid, used by central heating engineers to clean central heating systems, it is a flocculating agent (raises sludge into solution) which wont damage anything in the engine or rad, I drain the system out bang a litre of that in 1st and then just top up with water, run the engine up to temperature and let it cool a few times and then drain it all out WOWZER you have never seen as much black crud, after that the effieciency of the rad was restored and the temp reduced significantly, well chuffed, you can get it from any plumbers merchants for about £10 for a litre or pay loads more for the same stuff RAD FLUSH from your motor factor and only get 250ml. I thought my coolant and system was clean until I did this