Melo928

Hi,

Can anyone confirm which side up bimetallic strip should be installed into viscous clutch? When it’s getting warm should it push or release pin? Based on topics and pictures I found - watermark style text is facing forward and it is bending forward (not pushing that pin) when warming. Is that right?

Thanks,

-mikko

GlennD

Greetings,
I looked at both of my spare couplers and both have the bi-metal strip as you describe. The 928 part number is on the outside and the strip is convex (when looking from the pin side).

Cheers
Glenn

Melo928

Thanks Glenn

Convex when cold? Hmm, mine is flat when cold and bending to text side if heaten.

In your case pin is pressured into very bottom when coupler is cold. Heat will release pin and lock clutch. I think mine (pin) is now in middleways. Should I bend my strip to convex? All instructions says "do not bend" but how it came from the factory - straight or convex..

-mikko

GlennD

Sorry - can't tell you what to do with the strip. I never tried bending mine.
If your pin is not pressed all the way to the bottom, does that mean that your fan coupling is engaged? I would think that would give better cooling earlier.

When I said that my strip was convex when cold, it is just ever so slightly off straight.

I need to check mine again (refill while I run with a spare unit) and will post what I find. I will be taking apart and re-filling. Weekend activity

Perhaps someone else with a more recent memory of the viscous coupler could chime in and share a few pointers w.r.t the bimetal strip

Glenn

Landseer

I think it presses the center pin inwards when heated.
Will post some support info for you to sort through, ok?
Following various embedded links should help.

http://forums.pelicanparts.com/porsc...indicator.html

http://porsche928forums.com/viewtopi...lit=fan+clutch

G Man

I refilled my fan with fluid a while back and found that the rubber seal in the center of the clutch was very hard and brittle. It didn't seem to me that it would be able to seal around the little pin that goes through it into the clutch. Anyone know of a suitable replacement for this seal?

Melo928

My capability to understand english is limited. In picture text they say bi-metal part "buckle" ie. bends in when heaten. In diagram they show that in warm situation bi-metal strip is rised from cold position. WTF.

G Man. I think you don't need that seal. In other version that I have it does not even exist. Fan is supposed to keep always vertical and there is not enough silicon to escape via pin hole. I Could be wrong.

Landseer

Well, the 2 photos are of my fan. It works! Let that be the guide.

I suspect it needs to seal. Otherwise dirt/water could enter.

Melo928

Mine has no seal nor porsche P/N. identical to this http://members.rennlist.com/blueshark/page13.html

There says that watermarks side up and diagram supports that idea. Glenn could heat bi-metallic strip and see which way it will bend. Maybe I'm just too obsessed with these details ; )

Landseer

Well, you can't go too far wrong working on this.

What year, btw?

Melo928

Car is -84 Euro S

If you put it wrong side up it'll be stiff when cold and loose when hot

Melo928

Question: Can you overfill the clutch so that its rotating solid also above 3400 rpms?

and if possible how would that effect to engine performance?

jpitman2

I think in worst case the fluid will always slip some, as it says in the factory note - speed limiting, as there is no lockup.
I refilled mine once, but it spat all the silicon out pretty quickly once reinstalled, so I have gone electric.
jp 83 Euro S AT 54k