986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - Help: Alternator needs replacing at 42,000 mi? Price jacked up in past year?

socratic · 09-07-2005, 10:31 PM

Ok, so here's the outcome.

The dealer put the rebuilt alternator back. It's running fine, probably better than when I got it a few months ago. Note, originally there was a rattling sound that indicated a bad pulley. Similar to what was experience by the fellow who posted this topic:

Lost my idler pulley Fri.

So the combination of a bad pulley and a worn rotor in the alternator caused a variety of "bad engine noises": a low frequency rumble/rattle at low rpms and a sound that I had originally thought was a gearbox whine around 3000rpm.

All the noises are now gone and the engine sounds very smooth again.

I advise people to listen carefully to the sound their engine makes. If you hear an abnormal rattle or low frequency rumble then it might very well be a pulley(s) and/or the a worn rotor in the alternator. Get it serviced as soon as you can. I noticed in mine that once the wear in either the pulley or the alternator (or both) manifests itself, it gets worse quickly.

If it turns out that it's a worn rotor in the alternator, you may want to consider doing what I did, namely: have the alternator rebuilt by a specialty shop for about $150 USD instead of paying $1100 for an OEM Porsche alternator. Only time will tell how well the rebuild went, but the new pulleys and re-worked rotor in the alternator returned my Boxster engine to the sweet sounding beauty it was before.

09-07-2005, 10:31 PM	#9
socratic Registered User Join Date: Feb 2005 Location: Canada Posts: 183	Ok, so here's the outcome. The dealer put the rebuilt alternator back. It's running fine, probably better than when I got it a few months ago. Note, originally there was a rattling sound that indicated a bad pulley. Similar to what was experience by the fellow who posted this topic: Lost my idler pulley Fri. So the combination of a bad pulley and a worn rotor in the alternator caused a variety of "bad engine noises": a low frequency rumble/rattle at low rpms and a sound that I had originally thought was a gearbox whine around 3000rpm. All the noises are now gone and the engine sounds very smooth again. I advise people to listen carefully to the sound their engine makes. If you hear an abnormal rattle or low frequency rumble then it might very well be a pulley(s) and/or the a worn rotor in the alternator. Get it serviced as soon as you can. I noticed in mine that once the wear in either the pulley or the alternator (or both) manifests itself, it gets worse quickly. If it turns out that it's a worn rotor in the alternator, you may want to consider doing what I did, namely: have the alternator rebuilt by a specialty shop for about $150 USD instead of paying $1100 for an OEM Porsche alternator. Only time will tell how well the rebuild went, but the new pulleys and re-worked rotor in the alternator returned my Boxster engine to the sweet sounding beauty it was before.