Cosmo Kramer

Knee deep in my 88 S4 project, the oil pump gear is in need to either be replaced or recoated. I know the new gear is steel because Porsche changed the part in 1990. I also read that the alloy gears are prone to cracking. How frequently has this happened does anyone know? My alloy gear has no cracks or stress marks and has been on there for 27 years and 130,000 miles.

Just wondering...

wpgshark

My 88, 160k km had stress cracks, almost needed a magnifying glass to see them. The 89 with 100 k was OK.

davek9

The aluminum gear needs/requures a small washer between the gear back and the pump, if using the steel gear this washer needs to be removed.

Guess all depends on how you plan on driving the car if deciding to reuse the aluminum gear.
Porsche changed to steel for a reason, right

928Myles

It's your car and your decision.... BUT
The steel gear is reasonably cheap and the consequences of a broken pump gear quite expensive......

I would personally change it out, especially as your old one is not in good condition anyway.

I remember a post where it was opined that it was only a matter of time before the alloy ones broke.

Myles

Cosmo Kramer

Thanks for the replies, new gear it is! I was just wondering if anyone here had ever seen a timing belt failure due to the gear breaking (I know some have had the nut back off and came off the shaft).