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During my last drive, I used my ac for the first time. Coincidentally, my fan also started squealing really from rubbing the bottom of the fan housing. Any ideas? Bad bearings in the alternator? Never seen this before on any 911 I've owned.
Inspect your fan when you get it off... might be time to do fan+fan bearing. The new fan is about $450 with the fan bearing (bearing alone is about $225), so if your fan has any visible issues its worth buying the whole fan now.
Very informative. Have a 95 , 30,000 miles, fan started making a zinging at 3000rpm yesterday. Checked clearance to housing, top and sides, .014 , bottom feeler gauge won’t slide through. Start with fan bearing?
Very informative. Have a 95 , 30,000 miles, fan started making a zinging at 3000rpm yesterday. Checked clearance to housing, top and sides, .014 , bottom feeler gauge won’t slide through. Start with fan bearing?
Rick,
I have a near-new fan bearing that I'm selling for cheap. Contact me if you're interested.
A while back I noticed some wear on the fan tips and a mark around the fan housing. Once things were apart the fan bearing was found to be bad so I got a new fan.
While putting things back together, it was noticed the fan housing tabs for mounting the alternator were cracked and in fact the entire fan housing was a bit out of round. So I need a new fan housing as well. Not easy to find, and not exactly inexpensive...
At any rate, I bring this up to say you might want to check your fan housing for signs of cracking as well. I don't believe this is a "common" issue, but the cars are over 20 years old now.
^ this. Those four ‘ears’ are a weak point on the fan housing. Even if they are not cracked, they often bend when the alternator is torqued down which means it does not seat properly in the housing.
Usually, this only shows when the alternator is replaced. Up until that point, 30 years of being seated correctly from the factory plus corrosion helped to keep it on the right place. You take it apart and it’s a different story.
We are working on a strengthening ring that goes on the back of the housing to address this problem.
As we make 175A and 240A versions of the 964/993 alternator we were getting lots of support issues after these were fitted. Of course, it wasn’t the alternator at all, just the fragile ‘ears’.
Another source of problems is the top hat shaped bearing for the double pulley. In the back, the bearing is held in by an internal circlip. This clip can vary in size depending on the supplier. The spacer that bears on the bearing must only seat on the inner of the bearing race. If it touches the circlip then it will bind and the fan will not sit square and wobble at speed. We have recently had to alter our alternator spacers to address this issue.
A lot of people over-torque the strap that holds the fan housing to the case, and over-tighten the v-belts. The belts need only be tight enough that they don't squeal or fly off at high RPM's, and no tighter. I see a lot of belts that are way too tight. All you're doing is killing bearings.
08-21-2014, 06:35 PM
Fan rubbing bottom of housing.
