So here’s another quick repair and yes I know, the engine bay is looking a little rough. Marc at Alpine Autowerks here in Calgary (which is a great operation, by the way) suggested I should coat the fan and housing in spray wax periodically, as it is raw magnesium and will corrode otherwise and this is evident in the below pictures. Well, the ravages of time have not been kind to the fan and housing. When I had it in for a service, Marc noted that the fan blades were contacting the housing.
After doing a bit of research here on Pelican Parts, I decided that the two likely causes were: (1) a bad alternator bearing; or (2) corroded fan blades and/or housing. It turned out to be the latter. So I pulled it all apart – with pictures below.
The housing had a number of small, hairline cracks in it, and there was one area where it was clear that the blades had been contacting the housing.
To remedy this, I pulled out my trusty Dremel to: (1) clearance the area where the blades were contacting; and (2) stress-relieve the cracks. I used a bit of JB Weld to cover up my ugly repair. Interestingly enough, it appears the previous owner had also performed this operation at some point.
Sadly, these parts are no longer available from Porsche, and the aftermarket replacements that exist are made out of aluminum, and are therefore significantly heavier than the genuine OEM parts. Plus the aftermarket replacements are hideously expensive. So hopefully this fix will hold.
One sad side effect was that the captive nut on the fan strap partially pulled through as I was tightening it down. I was using a torque wrench to torque it to spec, so I blame this one on metal fatigue. I ordered a new OEM fan from Pelican Parts and will install it at some point.