How far can I drive with a bad alternator?

A battery with failed internal cells will kill an alternator. You've got to load test the battery to see if it is the culprit.

A belt that is too tight will burn out your alternator bearings and kill it, too.

A short circuit *could* kill your alternator.

Extreme heat could kill it.

A really bad oil leak dripping onto it could kill it, too.

Your voltmeter in the cig lighter was a great idea!

 

Having similar problem with repeated (91) 348 alternator failures. Had a look and cant see a heat shield at all. Can anyone help I cant see it on any parts list, does the 348 alternator have a heat shield and anyone got part number??
thanks

 

The old 308s have a heat shield on the back of the alternator, and the wiring runs in a plastic tube for protection as well......

I had mine in my hands yesterday but it's back under the car now.

It's a double plate of aluminum with four mounting tabs, allows about an inch of air between the plates and the rear of the unit.....

 

Think I may have answered my own question, found this http://www.eurospares.co.uk/partsListing.asp?M=1&Mo=433&A=1&B=23684&S=&ID4=1022707 showing older alternator heat shield, newer one doesn't seem to have one. Just not sure which category I fit in.

 

Hmmmm....different configuration but that's doing much the same function.....someone must have lost yours or a design update?

 

the alternator sense wire comes to mind. I dunno where the other end of it is attached, but it's job is to tell the voltage regulator what the voltage is at some point far away from the alternator (usually someplace near the battery or other main power distribution point).

the vr then fiddles with the alternator to maintain the desired value at that remote point, which takes care of correcting for loads and other parasitic losses. A flaky sense wire will cause the system voltage to bounce around. Whether a busted sense wire causes the alternator to full field depends on the vr.

I've never worked on a 355, so dunno where the alternator wiring is routed. Any chance of the wiring getting damaged when the engine subframe is r&red?

 

I may have the answer to 355 problems. Fisrt can anyone tell me if the 355 uses a 1 or 3 wire alternator?

 

3 or 4 wire. pretty hard to have a sense wire on a 1-wire alternator

 

Well then you see where I am going with this. I have no clue what your dealer did but he replaced parts and does not check the electrical system. Time for a new mechanic. He has had 6 trys now FNA or not. For example Did he check the voltage at the main junction or battery vs the back of the alternator with all accessories on? Did he measure the voltage drop across output of alt to main junction? Does the alternator compensate for this drop via proper sensing wire to the internal voltage regulator? I can only assume the alts he replaces with are good. But did anyone do a preinstall check of not only voltage on a testor but amp output? Some shops do not have the proper test equipment and so the alt passes a voltage test and they think it is o.k.. I think you have a wiring problem that is draining off the battery and the alts can't keep up because the voltage drop accross crappy Ferrari wires and the sensing wire is not telling the voltage regulator to turn on more power. If you have any aftermarket huge stereo stuff this is made worse. Also, driving style can have an effect as Dave Helms illuded to the rpm of the 355 is much higher than the American cars the alts are designed for. Ferrari compensates by guessing how you will drive and in the pully size of the alts. Ferrari uses standard alts and adapts to their high rpm use. The problem is when drivers take short trips and half the trip is like they are worried they will break the car keeping rpm low. Rarely do I see Ferrari drivers even come close to breaking speed limits. Most dare I say ...drive like miss daisy further worsening alt production problems.