Rally Guy

Okay - DO NOT use a two-prong puller when trying to remove the cooling fan for a fan bearing/alternator replacement.

Why?

Here's why!

Based on this damage - can the fan be repaired/rebalanced? Or, does it not really matter? The nick is small and the material is really light.

However - an imbalanced fan will put quite a load on the Fan bearing, no? And THIS is exactly what I'm in there to fix!

On top of this problem - I can't get the Fan (let alone the bearing) off. Can I heat the Fan?

RK

PS. Just re-read this and have two ideas...

1. Fill the cavity with liquid metal, sand smooth. Should approximate the weight of the missing material, within a few 10ths of a gram?

2. Dremel out a similar cavity OPPOSITE this one - again to get the fan near balanced.

Thougths on these to paths to "balance"?

Thanks in advance.

darth

I Tig welded a fin about 10 years ago, it's still holding. You could try some good quality epoxy like Belzona since there's not much stress in that area or just leave it off. The dirt these fans accumalated on the outer circumference is equal to if not greater than to cause an inbalance than the piece you broke off being so close to the inside. Or if you're really concerned remove an equal size piece on the opposite side with a Dremel.

Bill

Rally Guy

Excellent news - thanks for the confirmation. My plan is to clean the fan up - epoxy or "liquid metal" that area - then sand and paint. You'll never know I was this stupid. : )

However - STILL don't have the Fan or bearing off - tips?

RK

Rocket Rob

I just removed my alternator to replace a bad fan bearing. I'm glad I didn't have this happen. Eek! I used a three arm puller, rather than a two. Not sure if that difference was critical. It just happened to be what I have. I used the same puller to remove the bearing from the alternator. The way, we did it. My friend was wrenching the puller while I provided a counter torque with a long 3/8 ratchet extension placed between two of the puller arms. Every few turns, we tapped the bearing with a hammer, hoping the penetrating oil would loosen things up. Eventually, the bearing started to move, slowly.

Once the bearing was off, I could see some rust on the alternator shaft. We sanded that smooth with some emery cloth. I will be placing an order for a new fan and bearing tonight. My bearing was completely shot and the a few of the fan blade tips are broken from contact with the fan housing. I'd rather have a new fan, just to be safe. Did you know that the bearing comes with the cost of the fan?

Good luck on the epoxy repair. It sounds like its worth a try.

darth

Put some antiseize on the shaft before installing the bearing - should make things easier the next time - hoping there isn't a next time!

jimq

I got my new fan at Sunset Porsche. It was alot cheaper then any where else and had the bearing already mounted. Used fans were only $100 or so less then new. I used a Harbor Freight 3 leg puller to get the old fan off the shaft.

garrett376

I also have had no issue using a 3-prong puller... that might be why that happened..

Rally Guy

Yup - I'm thinking/hoping 3 prong is the key - but I'm out of time for awhile so will take to a local shop for disasssembly. Need to be totally ready for reassembly as soon as possible - otherwise it'll be weeks till I can drive it again - and I can't handle that!

Ordered new Fan bearing and Alternator. Alt bearings don't sound too bad - but for a couple hundred bucks - I don't really want to do all this again. Easy enough to do - just fiddly.

Also getting new coils and belts.

Anything else "while I'm in there"??

RK

jimq

Powder coat the shroud

Porsche917K

Yep, you must use a three prong puller. The fan is on too tight to use a two prong given how soft the magnesium fans are.

Either way, this fan spins at a pretty high RPM and ages pretty poorly from what I have seen given the material it is made out of. I would start looking for a replacement. 964's and 993's use the same fan BTW.

springer3

+1 on the 3-prong puller. I also applied PB blaster, heat using an electric air gun, and impact using a hammer and a brass drift punch. One cycle of PB, one cycle of heat, and a couple of taps on the brass was followed by a gentle turn on the puller screw. After about a dozen cycles, the thing was off, and I never gave the puller more than a wrist twist.

I would not epoxy that area - too much risk of the piece flying off at redline and doing harm. Smoothing that with a die grinder, and then making the same shape on the opposite side is a way to balance the esthetics. Inspect for cracks regularly, and you should be fine.

Rally Guy

Thanks for all the advice - will report back on repair.

RK

jimq

there are 2 or 3 Fan numbers for the 964 and each uses a different size pully. I found this out when I replaced mine. The updated fan is the same one TIPs used with the TIP pulley set.

Porsche917K

Good to know