I think its time for a new fan!!
 

So, I end up with friday off so I start to tackle my alternator replacement and get it all out wich wasn't too bad and what else do I find? A 1/4 chunk of a fan blade is gone. $h!# now I guess I will have to try to find one. Any ideas where to look for an fan for an 82 SC? http://forums.pelicanparts.com/uploa...1140813493.jpg

That doesn't look too bad. I don't think it needs to be replaced.

Hi!
Why bother (unless it is really buggin you)? it is on the back side and no one will really see it. Plus the broken piece is so small I don't think it would cause any significant balance problems or excessive wear on the alt. I have a piece like that off of my fan too, no problem, and it is not visually noticible.
Cheers,
.Steven
1980 911SC

Take a similar chunk out of the opposite blade if you are scared about balance.

Unless you've got yourself a concourse car I wouldn't sweat that one bit. Even the miniscule bit of weight that piece had is, I doubt, enough to throw anything off balance.

JMO

I had the same thing. I used a dremel tool and sanded down the area to relieve any stress fractures. It shouldn't be a problem.

anybody know the max speeds these fans turn at? anyway, they don't spin like a centrifuge, so i'd agree, unless someone can state for a fact that this condition would cause premature alternator bearing failure. i wouldn't sweat it..but sure enough someone will post a horror story! ;)
ryan

Depending on your sustained RPMs -you could be generating a fair amount of angular momentum

Angular momentum = moment of inertia × angular velocity

L = Iw

[L - angular momentum (kg m2 s-1); I - moment of inertia (kg m2); w - angular velocity (rad/s)

Basically, at least two (fan pulley is smaller) rotations of the fan for every engine revolution translates to >>12,000 revolutions/min @ Red line (this may upset the alternator bearing some -on the Track)

thats an easy fix I just welded one up last week

I guess I am just going to clean it up and reinstall it as is. I sounds like this is not that big of a deal. (I hope). Ben I would be interested in hearing about your fix on this. Thanks, Derek

ben, did you use your tig welder for this? did you have the broken piece? i'm guessing derek doesn't have the chip that's missing..
ryan

just be sure to subtract the weld seam from the total amount of material to be added... :)


Seriously, don't worry about such a tiny piece. I 'm confident the Porsche engineers added enough tolerance to the fan and bearing.

The fans are magnesium and I did not have the broken piece I just built it up with weld. Most shops do not weld mag as it cost a couple hundred dollars per pound of filler rod so you may have to search around. I have been fixing these for several years for local p-car guys

after its welded up you just hand file it back to shape and you can blend with sand paper or what ever gets you fancy

cool stuff, ben. guess you're the 'mag man' on the board.. ;) we've got specialists here for everything. :)
ryan

I guess so!