Originally Posted by
vee8auto
suggest you just replace it, and I would advise anyone with a viscous clutch fan thats done more than 150,000 kms to just do it.
Mine on my V8 Disco was giving me grief from about 150,000 kms and I spent a lot of money over 3 years chasing an overheat problem not knowing it was the fan all along. If it wasnt for my engine oil pressure gauge I would never have picked it up. Unfortunately I was up around Exmouth when I worked it out.
The clutch wears out, usually through loss of fluid past the shaft seal, and it can happen slowly, or suddenly.
Its virtually impossible to find any guide on the internet on how to check them, but once you see a fresh one working its all very clear that the old one wasnt doing its job.
If the fan is a separate unit have a good look at the base of each balde and you will probably see hairline cracks.
Check with good Landrover parts suppliers and they will probably have access to OEM clutches and fans at reasonable prices.