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[TheBoy]

Well live in France... It is needed, in traffic jams or in mountainous areas in summer.
My brand new, BMW-sourced viscous clutch is already busted, after three days. Always engaged, although temp is normal. Even from cold.
As Americans would put it, bummer.

Isn't that northern france?

To be honest, the leccy fans should be more than enough in traffic...

[Pitchfork]

I'm on my fifth defective brand new one, all from BMW!
They tell me it's my fault, my car is rotten, they've never had a problem before.

Leur dire que c'est une charge de testicules!

[chartz]

I'm on my fifth defective brand new one, all from BMW!
They tell me it's my fault, my car is rotten, they've never had a problem before.

Leur dire que c'est une charge de testicules!

Une bande de crétins.

[TheBoy]

I'm on my fifth defective brand new one, all from BMW!
They tell me it's my fault, my car is rotten, they've never had a problem before.

Leur dire que c'est une charge de testicules!

Une bande de crétins.

PMSL

[Pitchfork]

I'm on my fifth defective brand new one, all from BMW!
They tell me it's my fault, my car is rotten, they've never had a problem before.

Leur dire que c'est une charge de testicules!

Une bande de crétins.

PMSL

Avec la merde pour le cerveau!

[chartz]

OK, cut out the funny stuff.
Seriously?

[Pitchfork]

Sérieusement, selon le garçon, ils doivent être entreposés et transportés verticalement.

[TheBoy]

there is no reason why yours should be eating viscous fans, other than the fact that correct storage is critical, and that viscous is an unreliable, crap technology. Always was, and it hasn't been developed for years.  Viscous does have a place, but not in a road car!

[Omegatoy]

thats just plain weird for 5 to go in the same way, as its only the viscosity of the fluid(silicon i think) in the hub that drives the fan blades, and it is supposed to only thicken up when it gets heat from the radiator to thicken and start driving the fan,when it cools down it freewheels and doesnt drive the fan, are you getting new hubs or the complete assembly with fanblades attached? cos im wondering if a different fan may help. stranger things have happened!!
could try and  get yourself a can of freezer spray that is used for freezing pipes by plumbers and spray it on the hub to see if it does let go,  although it is normal for a viscous to come on when engine is started from cold it usually only lasts a minute or so then frees off to freewheel till engine is hot

[Pitchfork]

thats just plain weird for 5 to go in the same way, as its only the viscosity of the fluid(silicon i think) in the hub that drives the fan blades, and it is supposed to only thicken up when it gets heat from the radiator to thicken and start driving the fan,when it cools down it freewheels and doesnt drive the fan, are you getting new hubs or the complete assembly with fanblades attached? cos im wondering if a different fan may help. stranger things have happened!!
could try and  get yourself a can of freezer spray that is used for freezing pipes by plumbers and spray it on the hub to see if it does let go,  although it is normal for a viscous to come on when engine is started from cold it usually only lasts a minute or so then frees off to freewheel till engine is hot

That's a damn good idea, it will be interesting to see what effect it has on mine that is permanently engaged especially if I spray it once the engine is hot
Any idea of the failure mechanism that would cause it to lock?

[chartz]

The problem is the thing is always engaged, whether hot or cold.
The other day I pulled over after a one hour  drive and when I put my hand between the fan and the radiator, the latter was completely cold, not even lukewarm! After a minute or so, the radiator became lukewarm, then I started the engine and it became hot quite quickly. So theoretically, the viscous clutch shouldn't have  been engaged at all, since it's temperature-sensitive. The air flow is so powerful that it always keeps that part cold. Puzzling, this.

[TheBoy]

The problem is the thing is always engaged, whether hot or cold.
The other day I pulled over after a one hour  drive and when I put my hand between the fan and the radiator, the latter was completely cold, not even lukewarm! After a minute or so, the radiator became lukewarm, then I started the engine and it became hot quite quickly. So theoretically, the viscous clutch shouldn't have  been engaged at all, since it's temperature-sensitive. The air flow is so powerful that it always keeps that part cold. Puzzling, this.

The 3 I had in my garage were all the same. The noise and the power sapping was what made me rip them out and stay out. Crap idea. Unnecessary on a road car.

For info, most viscous, even when working right, will be engaged when cold for a min or so before it starts to freewheel a bit. This is normal.

[unlucky alf]

blimey & i only asked a simple question back on post 1 , it now seems to become a right hornets nest

[Omegatoy]

thats just plain weird for 5 to go in the same way, as its only the viscosity of the fluid(silicon i think) in the hub that drives the fan blades, and it is supposed to only thicken up when it gets heat from the radiator to thicken and start driving the fan,when it cools down it freewheels and doesnt drive the fan, are you getting new hubs or the complete assembly with fanblades attached? cos im wondering if a different fan may help. stranger things have happened!!
could try and  get yourself a can of freezer spray that is used for freezing pipes by plumbers and spray it on the hub to see if it does let go,  although it is normal for a viscous to come on when engine is started from cold it usually only lasts a minute or so then frees off to freewheel till engine is hot

That's a damn good idea, it will be interesting to see what effect it has on mine that is permanently engaged especially if I spray it once the engine is hot
Any idea of the failure mechanism that would cause it to lock?

two possible reasons
1 fluid had leaked out
2 early viscous used to be triggered by a bi metallic strip bending with the heat wonder if these are triggered by this method?   
 reason i asked if the just the hub was changed is just to eliminate a unbalanced fan causing vibration which in theory could cause it to lock up its the only thing i can think of!!! 5 hubs all going the same way?

[chartz]

Okay then,. I'll end up changing the fan itself if it comes to that. I shall keep you informed.