The dreaded electro viscous fan - maybe a fix?

[Dr.Fiero]

Hi all

I had to replace the water pump, so had everything apart anyhow.

I was feeling cheapskate'ish and didn't feel like replacing the coupling - It had been slipping for the last 7 years or so (hey, don't rush me!) but it was only a concern in the summer and the AC was on AND we were driving in stop/go traffic... which where I live just isn't a concern... but the AC would stop working, and in an extreme the engine would start to overheat.

Anyhow, I wish I'd taken some pictures, but didn't. So... you're stuck with a text description.

I stuck the coupling in my vice, nut down. Used a drift/punch, and unthread the 'back' of the coupling. There's 2 notches which makes it super easy. I'd previously bought some silicone shock oil (500cst which it turns out is a bit too light weight - should have gone 1000-2000). Added about 40-50cc's of the 60cc bottle. Cleaned everything up, put it back together (and crossed my fingers!).

New pump went it, the experimental fixed coupling went it. The second I fired it up, you could hear the difference!! It was coupling FAAAAAR more than it had ever done since I've owned it. I was starting to think I'd gone overboard! But after driving it up/down the block, and letting it warm right up it calmed down.

I'll have to wait for a hot day to see how well it really works, but so far so good - and ~$20 beats $100+ for a new one!

 

[TJBaker57]

wish I'd taken some pictures, but didn't. So... you're stuck with a text description

I have opened a couple. Found at least 2 variants. One had an O-ring seal and used shims to control the amount the valve would open? Another type had neither.










Here is a look at the valve mechanism being moved with a magnet..

 

[Dr.Fiero]

Excellent! Mine was the top, and had that shim washer you referred to.

This now also relieves me of the nagging urge to take it apart again to document things better.

 

[Mooseman]

My question would be, was the failure caused by a loss of the silicone oil? If it's overfilled now, wouldn't it make it engage more because the extra fluid has no other place to go?

None of my failed EV clutches had any evidence of leaking silicone. My last one looked fine, no leakage, but it just wouldn't engage when commanded by the Tech 2. I just installed a thermal I had laying around.

 

[Dr.Fiero]

Well, had a chance to drive it a few times now.

While yes, there is a chance I went overboard on the filling... there's no doubt that it's actually doing something (you know - blowing air! Ha!) now, that it never has since I bought it in '17.

I have no intention of pulling it out again (anytime soon anyhow) to do test #2, but I'm suspecting that the fluid had simply broken down viscosity wise. I couldn't SEE any evidence of leakage.

I also have almost no other frame of reference! But the fact that I could very easily spin the fan (engine off - duh) just didn't seem right. Now, it's much stiffer. Would be like spinning a bowl in a sink filled with water before, now it's like a bowl in a sink filled with... runny honey?