v belts

[pzi993]

Well my 25 year old 993 suffered interesting chain failure worth sharing. The alternator 12 point shaft and tool became let's say unreliable. I kept ignoring it applying "German method - apply force and if not working apply more force". This proved to be a mistake and after a few belt changes the shaft could not be well held with 12 point tool and the shaft nut was not well tighten. As a result I observed the following failure:

1. While driving the nut started slipping and the alternator pulley loosened and caught the belt that flew off.

2. Now the alternator stopped spinning but the cooling fan was rotating. What this does it puts the load on the fan bearing beyond its design. It spins with the full speed of the fan and in normal operation is just takes the difference of speed between alternator and the fan. This resulted in the bearing to seize and stop the cooling fan and rip the cooling fan belt.

3. The loss of cooling fan belt triggered the belt sensor on the dash. For some reason I did not understand that funny looking dash light - with the picture of the belt sensor - and I took it as an indicator of the ignition key battery low - which looked like my golf alltrack dash light.

4. Now with no belts and no cooling and no electricity generated the 993 is still driving. That is unusual achievement of German engineering.

5. The car overheats triggering the dash light. Now I get it and stop immediately.

All this was on my way to the Porsche dealership for the appointment to take my wheel lock nuts off after I misplaced the master key. The overheating light went on right in front of the dealership so I just coasted to the dealership parking lot. I went to the service desk and described the situation. They are usually booked and could not take a look at this immediately so we left it in the parking lot till they can have a look and do the wheel locks as well. The next day a nice mp4 video is sent to me by email with the mechanic doing the full inspection of my 993 on the lift. Checking every point of inspection possible - the car showed to be in good shape but the fan/belt job was of course needed. Attached was the estimated bill for the new alternator, new cooling fan, v belts, new pulleys - ~$2k. I opted for the wheel locks to be taken off the car and car towed to my garage.

I ordered new fan bearing hub, belts, alternator and new 12 point shaft tool. Initially I intended to find a machine shop to press out and in the bearing hub in my old fan but after a few calls to machine shops around me I realized that nobody does anything mechanical anymore and standard answer was - "we don't do press jobs anymore". These are the "automotive machine shops" in their names and they have no hydraulic press.

Bought last in stock 12 ton press from harbor freight for $140 and did it myself. The pressing went super easy with 24mm impact socket as the pressing out tool. In the process I gave the magnesium cooling fan housing good scrub in my parts washer with the wire brush which resulted in nice shining surfaces. I did the inside and out with steel wool and now have slick shiny new center piece in the motor.

[OSC911]

Thanks for posting - gives me confidence to do this myself.
Cheers

[joebaehr]

Nice!

[viejopatron]

Greetings. I purchased a high-mileage '95 993 C2 from a friend in February and will be doing the same job as you did. As it has been several years since you did the effort, have you had any subsequent issues with that pesky bearing in the cooling fan?