OK, don't flame me because I searched all over the forum for this but couldn't find an answer.

My problem was a rattling noise under my hood. Sounds like a can of marbles rattling around. Intermittant, occasional and not terribly loud. I finally figured out the noise was from my alternator. A friend told me the bearings in GM alternators have been known to fail. The darn thing charges fine but the noise was getting worse so I ordered a nice remanufactured unit. There were a bunch of choices by I decided on the Bosch. It cost a little more than the cheapos but I know I can trust Bosch electrics and it was still less than half what an OEM would have cost.

Here's my question. The Bosch alternator arrives yesterday and it looks identical to my stock unit but it doesn't appear to have the clutch type pulley. I have read what the clutch does but can someone tell me if I absolutely have to switch these pulleys? It's not an impossible job but it will require special tools and expertise. I was all looking forward to just throwing in the new alternator since this is a very easy job in a C5. Can someone tell me if I can keep the pulley on that the new Bosch alternator came with or will the thing squeal and/or cause amperage read problems on my DIC?

Thanks for the help. This forum has helped me so much in the past with learning stuff about my Vette and it's really the only source of hard-to-get info that I trust.

Peace!

 

My recommendation is to return the Bosch & order a new unit from Gene Culley at GM Parts House - he has them listed for around $390 -/+ depending on whether a manual or auto.

With the time and aggravation to swap an old pulley on a new alternator, it's not worth it. The GM replacements are a newer design now so hopefully will hold up.

For something as important as the alternator, I think it's worth the extra $100 or so for a 10 minute job and piece of mind

 

http://forums.corvetteforum.com/search.php?do=process

Key Word: Alternator

User Name: Evil-Twin

Forum: C5 Tech




Read posts by Evil-Twin

 

But for different reasons, only OEM alternators (made in France) will give the correct "data reading" to your system. Without this, your DIC will be always giving you a "charge fault" message.

You don't say what year your C5 is (hard to help you if you don't fill out your profile). 1997-2000 C5s and '01-'02 6-speed cars including the Z06 take a special alternator, here is a post with comments from Evil Twin (a ex-GM Corvette Engineer):

http://forums.corvetteforum.com/show...r%2C+generator

 

the "clutch" type pulley was used on A4's exclusively...

starting around 2000 ???

if that's the only difference with your new one; you can transfer over the pulley from the original alternator.

 

Is your C5 a MN6 (manual transmission)? If so, does this noise only happen in 1st gear from a stop? You have described (marbles in a can) the noise that a MN6 clutch/transmission/driveshaft sometimes makes. This is even described on the C5 video.

 

Thanks for the input folks. I ended up installing the Bosch alternator even though I was a bit wary of complications. Returning the unit seemed like too much agg and the noise was getting loud under my hood. FYI, the Bosch unit couldn't look any more identical to my stock unit except for the pulley difference.

So after the easy install, I fire up my Vette and voila!, it works perfectly and the marbles in a can are gone! I've been running the car for about a week now and all seems well. No DIC error codes and steady charging is being reported. Quiet too. While not a glaring deficiency, I think the clutch pulley is still a good idea so I'm going to have a mechanic with the proper tools make the switch before I return the core. Reason? There seems to be, sometimes, a slight shudder detected in the tension pulley across the engine from the alternator when the engine is placed into D or R. I think the clutch pulley on the alternator probably absorbs that transition torque on the belt.

Anyhow, the part arrived quickly from Autohaus AZ, it installed even quicker, it looks very clean, operates well and the price was about half what a stock GM alternator would have been. Thanks again everyone for the info. I hope that maybe my experience can help someone else, especially if my friend was right in reporting that GM alternators have a history of bearing failure.



BTW, I have finally completed my profile. Sorry for the ommission.

 

Glad you solved your problem.

BTW, these later designed model GM alternators do NOT have a "history" of bearing failures however ANY bearing, given enough time, will eventually fail. FWIW, my original 1999 alternator with 151K+ miles on it is still going strong.

 

GM had the same problems with rear bearing failures on Tahoes etc. I had one completely lock up and stop my motor on my 93 Tahoe / Blazer. Then you could start it right back up, but it would randomly lock up.