Thread: Radiator fan hub working or not

From the Toyota Surf forums I used to follow (The Tojo's are notorious for getting hot under load) it seems the cheaper viscous fans are not very good.

I'm not sure if it's a similar issue here with a different make, but I'm thinking it could be.

Do you hear the fan 'roar' when the the engine is revved when hot?

You're probably right re the cheaper fans. I don't know. Am kicking myself a bit now for going cheap. Having said that, when you ask me if I hear the roar when the engine is "hot" I have never heard that in 5 years. I had it done a week or so ago and its winter now and even after a 1 hour drive I doubt you could say it was "hot". Infact most times I reckon after even a long drive you could put your hand comfortably on the tappit cover. Might be a different story on a hot summer day in traffic or under load. If "hot" means normal working temperature I haven't heard that roar. Not sure when these things are sposed to kick in? Maybe if the temperature started climbing past normal it will kick in?

The activation temp is about 95-110c at the fan hub, and you should hear a roar for a few seconds at cold startup until the oil is redistributed around the hub. If your cooling system is ok you may never hear it engage. I certainly know when my D2 one engages - slow climb in low range in summer with an auto. Makes a lot of noise.
Terry

How hot is 'getting hot'? How many Km's?

Many diagnose the viscous unit as failed the first time the engine gets abnormally hot when infact the head gasket has let go between the back two cylinders.

Not trying to worry or jump to concussions but I have replaced many 200tdi head gaskets when I was in the UK for this very reason.

Head gasket failure interval on a 200tdi in the UK was reliably 100,000 - 120,000 miles. Swapping the gasket is pretty quick and easy if you get in there and catch it early.

Chances are there will be no other tell tale signs...

If you go this route, new head bolts.