So I went back to the mechanical clutch fan on my '91 3.0 4Runner replacing the non-working flex-a-lite. It seems to work fine, but I have a question.

I know when the clutch is cold, I should be able to spin the fan fairly easily as the clutch is fairly free. Obviously the tension in the system is enough however that if you were to start the engine, the fan still turns. My question is when the engine hits operating temps for a spell (and I am not overheating now so I think it is working,) shouldn't the clutch be nearly locked up? When I kill the engine and try to move the fan, it moves just about as easily as it did when cold! I would think that the clutch (when hot) would lock up and be very stiff or difficult to free spin.

Do I have a dud clutch? I hope not as I really don't want to try to replace, but not sure what to expect. Again, no over heat issues, but it has only been a week and I haven't driven it much.

JJ

 

Here is a pretty good article on how the viscous fluid clutch operates. If it is indeed bad, I'd replace it with an electric. In fact, why not replace it with an electric? If you need a clutch I'm sure someone on the forum has one they'd probably be willing to send you for just a few bucks.

http://www.popularmechanics.com/auto...t/1772922.html

 

a properly working hot fan clutch should be fairly stiff but you should still be able to move it.

 

Nice link wrench, I always wondered how they worked.

 

Sweet, I think it is working. I am just worried. No overheats however, but of course I've only been a few miles from the house. Wait till tomorrow when I am 50 miles away for the thing to crap out.

JJ

 

You will know when it locks on, It will suck the life out of your engine.
Mine is a little to sensative right now, Old cluch, Ive even sprayed the sping and seal to get it to not kick on so soon

 

Reading that article brings me to a few questions...

On my 90' when I let it sit overnight, and start it up, specially in the winter, my clutch fan is engaged, it sucks alot of air bigtime, after a little bit it free's up. <--- is that normal? If I let it sit overnight and try and spin it, its got resistance, it'll only spin as much as I push it.

Now when I turn the rig on, and the fan slows down, I can go out, and it'll spin maybe 1.5 - 2 times around. Crusing in town and it'll clutch, or lockup (not fully but like it should)

I just want to know if the initial startup thing is normal, some have told me its not, that article to me seems like thats not normal unless its an electric valve. Which I'm sure its not. The fan clutch works normal though. Just curious.