SNOWBIRD

Went over to the shop to pick up the new alt belts, and they offered to throw one on... As soon as the mechanic opens the hood he points at a fracture in the fan... I expected to come on here do a search and get 50 posts to choose from on the subject..... None???
Doesn't really matter just surprised. More surprised to find $550+ for mine and if it were a turbo $200.. huh? And the turbo only has 11 blades vs 12 on the na...
At least someone is gonna get a cool clock out of it.

Indycam

Cracking is not unheard of but
it is odd that it cracks , imho .
Something is not right when a part like that does not last and last and last .

jimq

braking belts, broken fan. Sure sounds like something is not right .

SNOWBIRD

I've been thinking related issues too... I realize they are on the same shaft, but but but but... How could either one make the other bad? Would think a bearing would go... Harmonics? Has a new alternator too, the shaft on the old one was so buttered by someone using the wrong tool, I had to replace it a few years ago.. Maybe has 6,000 miles..

Indycam

The crack might have started long ago .
A small nick can grow and grow and grow .

Porsche917K

The blade ends started to splay on my fan. I think that some damage to fans occur when people separate the alternator from the fan housing and fail to get the housing seated back on the alternator properly. The fan runs very close to the housing and any interference combined with high RPM damages the fan quick!

AOW162435

Mike,
Make sure that the fan bearing (about $100 from Sunset) is tight as well. Any slop here can lead to the blades eventually machining the inside of the magnesium housing. My assumption is that these blades develop cracks either from contact with the housing (force) or from scratches in the coating that allow moisture to attack the magnesium (corrosion).


Andreas

Rocket Rob

When I purchased my C2, it had a cracked fan. When replacing it, I took the opportunity to have it powder coated red to match the car. :-)

How common is the problem? Not sure. You don't see mention of it on RL.

SNOWBIRD

Hmmm, my blades seem okay... Here is my fan.. Good idea on the powder coat, I think mine will be bright yellow, but out of a spray can.

jimq

you sure that isnt a scratch thats dirty? Looks like a strange place to have a failure.

SNOWBIRD

Made me look again, cleaned it a little.... Looks worse now

Indycam

That is a crazy crack .
Did it start at the blade and run down or did it start down at the vent and run up to the blade or what ?

Geoffrey

The fan is magnesium and it corrodes and cracks over time. DO NOT powder coat the fan, magnesium does not tolerate the heat from the powder coat oven very well, and you won't be able to see the fan cracking very well because the powder coat is so tough.

The Turbo uses the older 911 fan, not the newer 964/993 fan.

Indycam

What would be a good coating for the fan then ?

SNOWBIRD

Dunno how or where it started... Unlike most of you guys, I prefer to open the hood only as needed....
Geoffrey, think it's okay to spray paint?