Viscous Fan Coupling

In both BMW Concour events and in non-BMW events I have never been penalized for using a factory replacement part from BMW. When a part becomes NLA it is recognized and acceptable to use the proper replacement. And no one has ever asked if I have a 4 or 5 speed either. :D

(and my coupe has never overheated with the viscous clutch and nine blade fan even with an original two row core radiator, it stays below 3:00 on the gauge. And the real test has been sitting on Hwy 1 trying to leave Carmel Valley in August with a million other car week spectators!)
 
Bwana said:
Indeed, what is this piston of which yea speak?
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the piston is esential, this is the type of piston full of a fluid that expands when hot, the piston body is in contact with a sort of mini fan made of copper that sits in the red plastic fan body at the front

when hot air comes out from the radiator, the mini fan catches the heat and conducts it to the piston, the piston expands and presses the friction spyder that bends its arms and presses them against the metal cylinder and thus blocks it, so the two parts become one, and move together
 
Fan coupling.

Knew I had one tucked away. Is this what you want.
 

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Fan coupling

Yes it's unused as you can see it is new in (tatty) packet! I have upgraded to the later style viscous coupling, which was fitted to the last E9. PM me and we can discuss.
 
HB Chris said:
In both BMW Concour events and in non-BMW events I have never been penalized for using a factory replacement part from BMW. When a part becomes NLA it is recognized and acceptable to use the proper replacement. And no one has ever asked if I have a 4 or 5 speed either. :D
...
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Maybe so but when SFDon disassembled my E24 down to parts he found a power steering hose that was not OEM and even worse was from an American car. Don has not recovered from the shock. Rumor is that he is secluded at the Ashram in Mount Baldy where he can only post here when the monks are not watching...

When I get the car back I will modify the Karmann assembly plate to read assembled by Karma...
 
For the coming generations of readers to this thread I would like to add that the red 5-blade fan with a correct working friction coupling together with a radiator and engine with non internal oxidation will work just fine 24/7 :-)
(unless the average temp is +40 degree Celsius on the globe, when reading)
 
Well, call me slow but, as I understand this, the fan engages when the temperature passing thru it is above a certain value? The the piston moves somehow and engages the friction surfaces> So it is a temperature controlled fan, not a centrifugal fan, correct? I guess I've only dealt with centrifugals, never thought about on being controled by temperature.
 
Stefan said:
For the coming generations of readers to this thread I would like to add that the red 5-blade fan with a correct working friction coupling together with a radiator and engine with non internal oxidation will work just fine 24/7 :-)
(unless the average temp is +40 degree Celsius on the globe, when reading)
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Very kind of you to worry about coming generations.

Much better than my Louis XV motto: "Apres moi le culasse fissurée".
 
Bwana said:
Well, call me slow but, as I understand this, the fan engages when the temperature passing thru it is above a certain value? The the piston moves somehow and engages the friction surfaces> So it is a temperature controlled fan, not a centrifugal fan, correct? I guess I've only dealt with centrifugals, never thought about on being controled by temperature.
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Yes,
The piston is behind the copper fan looking device and when it heats up the piston (red center of brass fitting in middle of disk) moves in (toward engine) and that pushes on the center of the clutch disk, in toward engine and that moves the outside clutch surface towards the drive disk outer ring that then locks the fan to turn.

Note-in photo clutch disk is in housing that it locks too.
 

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I don't know about the viscous fan on these cars, but in the Porsche 928 community I was a member of for 18 years, the viscous fluid in the older models (starting in '78) is frequently replaced with new fluid. Might have to drill a hole in the fluid chamber of the BMW coupling, drain out the old fluid and install new silicon based fluid from Toyota. Plug the hole. IF anyone is interested, here is the 928 procedure link: http://www.nichols.nu/tip482.htm
Finally, here is a link with some comments about using the procedure, and pix of the installation on that cars viscous fan model: http://rennlist.com/forums/928-forum/569661-viscous-fan-re-fill.html


Edit: I found there is a new - better and cheaper replacement silicon fluid available. It is a Lucas fluid, $10 for 2 oz (NO - it does not have any electrical component!).

Available from a parts supplier friend of mine in the Dallas area - Roger Tyson, a 'Brit transplant'. Web site is: www.928sRus.com Roger prefers e-mails or telephone calls.
Roger supplies me with parts for my CS and my Sl55. Good source - no relationship other than a good guy and reliable supplier!
 
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That is the early viscous clutch which uses the standard water pump. The spin on model with the big nut requires a newer pump.
 
HB Chris said:
That is the early viscous clutch which uses the standard water pump. The spin on model with the big nut requires a newer pump.
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Thanks HB Chris because I bought these parts as well as a new water pump (same as existing) but then I started to think if it will fit on the existing water pump. Thanks for clarifying, you are very knowledgeable. Really appreciate it


Sent from my iPhone using Tapatalk
 
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