replaced the voltage regulator with a new aftermarket unit and had the alternator rebuilt.

car worked normally over the past week (good voltage readings), up to the time I shut engine down last night. driven daily, total about 200miles on new alt. This morning the battery meter dipped below 11V during warm up and got the red batt light plus "generator failure" warning.

Rained hard yesterday but the car's been in the garage over night. could it be water/belt slippage? - my thoughts are any water should have dried by now.

when alternators are "rebuilt", what's actually replaced? I was told the core and bearing on mine were replaced. Suppose the other possibility is the voltage regulator failed. But how to diagnose?... I'm stumped.

In the case, this is not water related, would like try and hone down the issue before giving up and getting a new OEM alt. Help...Thanks!

 

before you do that..there has to be a specialized car electrical system company in your area that can thoroughly check the alternator...they can bench load test it at several different rpm levels and tell you if there is a problem with it...you might find out that the alternator is not the problem...you may have a short somewhere that is causing the problem...it could be intermittent or possibly some wiring is exposed and gets affected by the rain (although the connectors are weather pak but someone could have replaced one with another that is not weather proof)...could be tough to find

 

Any pic of your engine bay between custom Y-pipe and wiring under Positive Terminal (wire from alternator)? This was my story. My 3" Y-pipe at F-hose section rubbed that wire. Under positive terminal, there was thin plastic shielded bare connector. It somehow rubbed under load or vibration. After driving 1-2months it made contact to wire, it short electricity from alternator to ground. My reg was blown.

 

thanks for suggestions guys. Next day car started and Voltage meter shot up just under 14V... might just be water on an exposed circuit. Question here is, if the water shorted the circuit, would it perm. damage it?

just glad it works for now, hopefully won't happen again, dont feel like tearing everything apart of a looksee.

 

FWIW I had the regulator replaced for $20 in my alternator in my 02 996 C4. It died 2 days later and had to replace the entire alternator.

 

I was told the 996 carrera and the 996TT alternators were the same, just different part numbers stamped and of course the TT being more $$. Anybody ever experience this?

 

When I change Alternator, Turbo Alt has fixed fluid clutch in pulley. It allows to slip little under high load and instant acceleration. 996 did not have it. I guess they know we want more power in TT.