BMW e36 316 fan cuts on when first started.

[evans14]

Hi guys,

Having changed rear diff & rear wheel bearing, noise from the rear has gone but another few problems have propped up

One is more serious looks like headgasket going, so will keep an eye on water / oil etc.

Another is when i start the engine, the fan is running at full speed, its not an electric fan, but im not sure how bmw fans work or what is controlling the fan ? how can I stop this happening ? what to look at ?

Cheers

[TheEnd]

It should run all the time, it's on the end of the water pump.

If it hasn't been running, then you'd have overheating problems.

[evans14]

Cheers for the reply just for my understanding... should it alter in speed ? I was told that at idle the fan should spin slow / not at all & increase with the revs, but it starts at full power, so when -6 the fan is cooling the engine, when in reality it does not need the fan until warm (or am I understanding it wrong) must get haynes book for this car.

[TheEnd]

It will always spin at about engine speed or just behind it.
It has a viscous clutch inside when stiffens up when it gets hot.

Right when you start the engine, it'll be quite stiff for a few minutes and then it will ease to almost freewheeling.
Because there is a small amount of drag, it will match the engine speed after a short while until it heats up and then it'll come close to locking and provide the cooling for the rad.