Visco clutch

[Jassper]

OK, I tested my visco clutch - when cold it would spin say 20x after the engine stopped, when over 100 degrees it would spin the same. Didn't take a lot to figure out the clutch did not work.

There still was some resistance against rotation but the resistance went away once the fan was turned a few times.

I took the clutch off yesterday and had a closer look. Everything seemed to be fine with it, when heated with hot air the bi-metallic strip would bend upwards and release a tiny rod, when cooler the strip would bend back down and press the rod inside.

I was lucky enough to have another visco clutch, non working that I put aside a few years back. I opened that clutch and collected all wax that was there. Drilled a hole in the first clutch, heated the wax (though the matter reminds me more of honey rather than wax) and poured it in. Made a thread, put a screw in the drilled hole.

Had it tested, it still rotates rather freely when cold but when over 100 degrees it rotated only say 8x instead of 20x. The problem now is that I have no bad clutch to open to collect the wax from.

Yet ... the wax when rubbed between my fingers reminded me strongly of one STP engine oil additive. The same colour, same consistency (being sticky and dense). I think I will buy a bottle today and pour some of it in the clutch. I can't make it much worse than it already is, but I can definitely make it better. Maybe. If not I will end up with having to buy a new clutch, which I would have to anyway had I not repaired it. If I succeed I will know a remedy for a shot visco clutch for a few $$$.

Btw - the rod operated 'valve' is no miracle - the rod, when in, presses on a metal strip which end covers a hole in a rotating plate. The cover is neither very tight nor very exactly shaped. Given the density of the wax it probably suffices though. When the bi-metallic strip bends up, the rod doesn't press on the metal strip and the hole opens a bit and the wax slowly gets beneath the second plate in the clutch causing more friction. I saw that the clutch could never really lock up, only increase its friction.

When the engine cooles down the hole closes (but as I say it isn't tight at all) and the wax that is there gets spinned off by centrifugal force and returns to a reservoir in the middle of the clutch.

Anyhow, will inject some of the oil additive in to the clutch and test whether it was a good idea.