Cooling fan thermal clutch

[tdwaters]

I have the water pump, fan, hoses and radiator off 84 BII. Is there a test for proper operation of thermal clutch? Replacing radiator and water pump and do not want to leave a questionable thermal clutch.

 

[ab_slack]

I don't believe it is a thermal clutch. If you are talking about the clutch on the radiator fan shaft.

So far as I know that clutch releases the fan from rotating at higher RPM to avoid the heavier load. I don't know if it decouples completely or lets it run slower.

There are only really one failure mode I have experienced. It doesn't decouple the fan so at higher RPMs the fan gets really loud. It becomes a significant part of the engine sound like that. It sounds like it is blowing lots of air.

The only test I know is to have it on there and see if it does this.

At the other extreme, I suppose it can fail so the fan doesn't really rotate much at all. I haven't ever experienced that tho.

 

[3rd Petal]

I don't know of any scientific test, but basically when the engine is off you should be able to spin the fan by hand but feel some resistance.
If it spins freely with no resistance it is wore out and probably won't spin the fan fast enough to cool the engine properly.
If it won't spin by hand it is seized up. It will still cool the engine when it is seized, but it will probably make the belt squeal at high RPM due to the resistance of trying to spin the fan so fast

 

[ab_slack]

If it won't spin by hand it is seized up. It will still cool the engine when it is seized, but it will probably make the belt squeal at high RPM due to the resistance of trying to spin the fan so fast

All three fan clutches I had that went bad, you could still turn it, they had that resistance, but they would not decouple do whatever they do at higher RPM so would run too fast.

The first instance the clutch had gone bad while I owned the vehicle. The other two instances it was already bad when I purchased the vehicle used. I've wondered if people just drove them that way not realizing what it was, just that the engine sounded odd but seemed to run.