New Viscous Fan Coupling

[t-tony]

It's full of wax, which is thinner when warm so likely to turn easier when it's warm?

Tony.

 

[Mint]

Quick one on this. When cold, and engine off, my fan will turn a little by hand (1/4 rotation maybe). However, when hot, and engine off, it rotates alot more freely. I thought it was meant to be the opposite?

My old one was a bit like that...

 

[antodeco]

Hmm. I'm trying to figure out if the fan is acting up and that's why I'm over heating in traffic. Might just replace it anyway

 

[Mint]

Hmm. I'm trying to figure out if the fan is acting up and that's why I'm over heating in traffic. Might just replace it anyway

That's exactly the issue I was having. Fine while moving, overheating when stationary

 

[buze]

I've just got a new coupling in mine, and the fan definitely starts when I start the engine (whooshing noise)... then eventually disengages. I didn't think this was supposed to work out like this? Is it normal?

 

[Delk]

I've just got a new coupling in mine, and the fan definitely starts when I start the engine (whooshing noise)... then eventually disengages. I didn't think this was supposed to work out like this? Is it normal?

It is normal. After the fan has been stationary it takes a little time for the fluid to flow all the way around the coupling.

 

[MalcQV]

I'll be doing this shortly. Mine is overheating in traffic. Both hoses get boiling hot and firm when on.
The fan is on from the moment the engine is turned on, and when engine is off, it's quite easy to turn it freely. I assume that suggests it's knackered?

Quick one on this. When cold, and engine off, my fan will turn a little by hand (1/4 rotation maybe). However, when hot, and engine off, it rotates alot more freely. I thought it was meant to be the opposite?

It's full of wax, which is thinner when warm so likely to turn easier when it's warm?

Tony.

My new one is more less like that. The difference is now, once the gauge needle creeps above ½ i hear the fan whooshing and it has not yet overheated again.

 

[roadvoyager1]

This article is a bit long winded but gives a good explanation of how the viscous coupling works and answers the question of why some fans start up rotating and others don't (which is not a failure).
http://www.silvertonradiators.co.za/index.php/2016-06-10-10-57-49/14-viscous-fan-clutches

 

[Mint]

This article is a bit long winded but gives a good explanation of how the viscous coupling works and answers the question of why some fans start up rotating and others don't (which is not a failure).
http://www.silvertonradiators.co.za/index.php/2016-06-10-10-57-49/14-viscous-fan-clutches

Brilliant article Robert, well found. As you say a bit wordy but it does explain why my new fan runs at start up and then goes quiet after a few mins...

'In a correctly functioning system when an engine is started the fan clutch will be engaged to exactly the same extent as it was when the engine was last shut down. This means that even if the engine is ice cold when started, the fan would be fully engaged if the engine was running at full thermal load when it was last shut down.'

 

[antodeco]

Just a quick one. Took the fan off today and put back on the new viscous fan. However, it doesn't seem to actually bolt onto anything? The M6 bolts just go straight through the shroud holes. Are they meant to bolt together or does the VF sit loose onto the shroud?

 

[antodeco]

Actually, I think is just my stupidity and not putting the bolts through the shroud

 

[antodeco]

Update on this. Fan replaced. Overall took less than 15 minutes. When I restarted the car, I could feel the air blasting against my face, and all dust shot up from below the car. Never experienced that before, so I'm assuming this is the fix it's needed. Will test it tomorrow on the way to work, and if all good, I can re-put back on the CAI I had taken off!