Verify your alternator pulley!
 

While rebuilding my spare alternator...
https://986forum.com/forums/performance-technical-chat/87604-rebuilding-alternator.html
... I discovered that the pulley was seized (they are supposed to act like a ratchet, locked in one direction and freewheeling in the other).
So I verified the pulley on my base Boxster that I am selling... and found it was seized also. I bought 2 new pulleys, and installed one in the car. I have now started preparing my Boxster S for its Spring coming out (of storage) and checked the pully... also is seized. Good thing that I bought 2.
That makes 3 seized pulleys out of 3 that I have checked. I am curious to know what other's experience is. I might add that that the pulley on my friend Newart's Cayman also failed, it came apart while driving and threw the accessory belt off, leaving him stranded.

Here they are...

http://986forum.com/forums/uploads02...1773169868.jpg

To remove and install you need these tools, I think they are standard for Bosch alternators.

http://986forum.com/forums/uploads02...1773169892.jpg

Whose pullies, OEM or aftermarket?

http://986forum.com/forums/uploads02...1773175903.jpg

All three are INA F 233525 1

Correct factory part to my knowledge is 997-603-154-01-M40, which is an INA 5350025100, which may or may not be the same part.

https://vehiclelifetimesolutions.sch...TQ4NGFhOGI0ZTY

I feel 1/3 of your pain (cuz I only had 1 boxster with a frozen overrunning clutch on the alternator and you have 3).

When I discovered it, it was because the bearings had also gone south, so the Easy Button was to replace the entire unit. That was after somewhere around 175k miles of year round driving in northwest NJ, so plenty of road salt, etc at play.

According to this chart the Porsche part number is the equivalent of the INA F 233525 1 which. in turn. on other sites is the equivalant to the number that you quote.

http://986forum.com/forums/uploads02...1773235731.jpg

I think it is safe to assume that all three of these pulleys are original from the factory.

I read the INA number off a factory part we happened to have in stock.

Checked mine today, and seized as well. What is actually the issue with them being seized? It would mean that the engine losing revs (while shifting) will also decelerate the alternator, but is that bad? Or is it a belt tension issue where the alternator starts to push the belt which loosens and might cause an issue?

Just wondering as I do not intend to run many more miles on this engine and wonder whether I should put in any effort, or just leave it as is (seeing that most alternators likely have a seized freewheel anyway)...

My understanding is that when you shift and the RPMs drop the alternator (with a seized pulley) will be pushing the the accessory belt and/or the belt has to act as a brake on the alternator. A working pulley will reduce wear and tear on the alternator and belt.

Finally found a pulley on an engine that was OK, while doing maintenance on my friend Tony's Boxster.

My original alternator (well, it looks like it had been replaced at some point) pulley was good, but I replaced the alternator with an upgraded 150A 987 one since I added the electric power steering. Not sure if it was strictly necessary, but I'm happy with it.