Stealth 993

Maybe the fan housing was strapped down to tightly and distorted it? That all looks weird.

Vandit

This is not the first time something like this has been posted on the this forum or the 964 forum. I can't find that older thread for some reason, but it was really similar to yours, no warning signs (i.e. visible cracks), just a sudden, catastrophic, failure that caused other damage to the car. I think the other guy lost an A/C line from the flying debris.

kjr914

Fan spinning with the engine off = fan belt gone. In the original pic posted, I believe what looks like the fan belt is the worn pulley surface. On the left side, there is no belt coming off the fan pulley down to the crank. You can see the alt belt going down to the crank, but no fan belt.

Black = corrosion.....holy cow that looks bad!

I just went through the belts, alternator replacement, and new fan+bearing install doing all the work myself, so I'm a bit too familiar with it all. Yep the paint is thick....my old fan was peeling, but I also had chipped fan blade tips and cracks in the ends of blades. The fan is a light alloy material and unfortunately it DOES have issues. I suspect this may be dependent on mileage/usage/temperature, so I wouldn't expect every car to be seeing this.

Pictures from my car below show the delam/cracking on the ends of the blades, unfortunately not the best pics:
Chipped paint and jagged crack on end of blade and chipped blade tip.


On the bottom of this blade, there is a 1/2"+ split forming (what I'd call delamination). You can see the split/opening in the end of the blade where there is a darker center section. The top side of the blade shows the deformation pretty well.


+993
One of the threads talking about this:
https://rennlist.com/forums/993-foru...djustment.html

IXLR8

Initially I was thinking black fan belt rub marks as you were, but impossible to tell from pics.

If that is corrosion, it started some time ago and periodic inspections should have picked it up, provided the parts/engine bay are kept clean. There are advantages to that.

I might guess poor handling of the fan assembly at some point, either while off the car or in the car....sort of like not knowing how to install bearings using correct installation procedures. Those tend to fail much sooner.

Out of curiosity, what is the ratio of the engine pulley to the fan pulley. I'd like to calculate the RPM at which these fans spin at.

levtron

My bay is kept very clean. I also had it all taken apart last May when I dropped the engine, and there were no signs of any issues, other then original hair line crack, which is not where it failed...

IXLR8

I've read about those hairline cracks on various threads on RL.

Its unfortunate the fan cannot be removed without loosening the whole assembly, otherwise I'd take it to work and have them go all out on it in the labs...X-ray and whatever else the NDT labs do.

Andy Roe

Hi guys,

Just to cross reference this, the fan on my 964 disintegrated earlier today. Here's a thread on the 964 board:
https://rennlist.com/forums/964-foru...tergrated.html

There was no warning of the failure at all, just a really loud bang!

Andy

BobbyT

These fan failures make me think of the early 911s--setting the timing was done with an old-school timing light, engine running at 6,000 rpm (fan probably spinning at 9,000), with your head pretty darn close to the fan in order to see the timing marks...

AllMine

Just for info sake... I just bought a 95 cab and 1 of the very few records that went with the car appears to be the same failure. I found a 2 inch piece of blade sitting down in the shroud (general engine tin to chassis shrouds) Looks like the repair cost 2600 bucks. New fan,shroud,pulley,belts,sensor,alternator... This was at 78,000 miles.
Curt