Brand new viscous fan coupling - What am I doing wrong

[Y_Cymro]

Before taking this back to GSF I thought I'd see if I am doing something wrong.

With the old coupling, the temp gauge climbed when my car was idling and stationary. Testing the fan with paper shows it doesn't work well when cold or hot.

Fitted a new one from GSF and there's considerably more resistance when cold and a satisfactory wooshing sound to evidence that it works well when the engine is revved up.

However, when the engine's hot there little viscosity in the coupling - it spins more freely - and no wooshing sound when the engine is revved. The engine gets hotter at idle and when driving than it did before the new coupling was fitted (the white line above 'normal'). I've not done the paper test yet.

Do you think I've just got a dodgy coupling or do I need to do something?

cheers

[stonesie]

It sounds very odd that, like its locking when it's cold and releasing when it's hot?


These things have to be stored correctly as indicated on the box or they can be buggerd before theyre even sold, unfortunatly most folk at these places don't take any notice of that kind of thing.

[Y_Cymro]

Exactly!

It works better when the engine's cold than hot!

[_bmw_316_lad_]

i bought one from gsf to recently and is the same as yours. i done the news paper test but it didint shred

[JJ26]

Nearly all viscous fans will be in a "locked" state when stone cold. Start your car when its stone cold, and hold its revs somewhere around 2500 or bit more, just so you can hear the whooshing sound. Normally after about 30 seconds to a minute you`ll hear it loosen up and the whooshing noice will be gone. That is normal operation. The unit will only ever "lockup" if sufficient heat hits its fins enough to operate the bimetalic strip in the centre of the unit. Is all the fan shrouding complete and in place? If not then the hot air passing from the rad will fly around the fan and not hit the unit properly effecting its operations. My 2p worth .

[spp320i]

Also worth checking the hoses are all getting hot, and your radiator too. If you have a dodgy thermostat or blocked radiator, that can stop the heat getting to the viscous clutch, so it'll never lock on.

I had this problem, and noticed that the bottom hose wasn't getting hot, so the viscous wasn't getting hot enough either. Changed the thermytwat and the problem was solved.

Let us know the outcome - it is entirely possible your viscous is fooked though, it wouldn't be the first time!

[30316]

To add my 2p worth I have had the same problem with 3 new vscous couplers! The 1st one came from Euro Car Parts. I took it back as faulty and they exchanged it but the 2nd one was the same. I then got one from GSF and that's the same! The one from dealers is listed as between £120 and £150 so I wonder if it is a question of what you get what you paid for?

I have checked the whole cooling system and it is all fine but the fan does not lock up when hot so I will be interested in the outcome.

[spp320i]

30316 - if you're certain the entire cooling system is ok - thermostat, rad, all pipes at correct temps etc etc, then it sounds like you've been pretty unlucky with your viscous couplings! Do you have a mate with a known working one that you can swap into yours to test?