348 alternator removal & rebuild

Thanks, found out my alt is working good at this point but still nice to be able to source the parts.

 

Another add on to this thread, for those with the smaller covers, I think a larger cover can be found here, along with other parts. Problem is you have to be an auto electric company.

COVERS

 

Just drift out the incorrect bolt and tap in the original bolt from the old regulator. Simple.

 

Hello everyone,

cool tread. I was looking at it coz, my battery wont charge anymore and today i was enoyed when restarting my355. My idle is also higher then usual (started two weeks ago) and now at 1250 iso 1050. The speed needle jumps so no and then and my cd sometimes restarts. so indeed i think my voltage is not what it should be. before owever, taking the alternator appart, i was wondering if there is a way to check/measure what exactly is gone bad, before by spares etc.. so, any knows what i should measure or verify first? i will already check the red wire going to battery also.
btw, can an over rpm be the cause, coz two weeks ago, i made a mistake by shifting just to late but saw i was just at the 9...

 

Hi all,

For those who needs to buy the parts in the UK, I can highly recommend Jim Roberts. I found this on ClubScuderia.com:

"Getting the bits is easy too now I've found the independent distributor in uk, now a sole trader having been laid off by company, not interested in selling these bits. Has them all in stock in back of his van. I just bought 4 sets for me and mates racing 355 challenges and just used one to rebuild recently clapped out alternator now humming!

Just ring, his name is Jim Roberts 07973 540449, delivers free in south east and will post national.

You need rectifier RN-10 and regulator VRH-2005_4A (last 3 digits may be superceded by new version but dont worry he'll get the right bits for you)."

I called him and he sent the parts in the mail the same afternoon! Great service.

Now looking forward to picking the alternator apart.

Carl

 

Hello guys,

I'm new to this brotherhood! I have a 1992 348tb with 98000km's on it (Canadian). I'm pretty sure I have read this entire thread twice and it has been very helpful.
My battery light would intermittently flicker and turn on under high rpm's, I measured my regulated voltage and found it was drifting below 12V at idle. I found a company who rebuilds lots of Ferrari alternators for a local Ferrari shop, I opted to have them rebuild mine.
They found (as this thread also found) that the alternator had been rebuilt in the past with inferior parts and an incorrect regulator.
My alternator is ND 101211-5071 (90A small body version).
It is now rebuilt with OE Denso bearings, aftermarket stator (170A), and OE Denso regulator 126000-1500. I said I thought it was suppose to be 126000-0400 regulator, but the guy said all the Ferrari's use the 1500 one (?).

The Problem: intermittent battery light issue is fixed, regulated voltage starts at 14.2V but drops to 12V or less as the car warms up. My alternator guy has bench tested this unit extensively to heat it up, but can't duplicate the problem. I've measured the voltage drop on the positive side at 0.13V, negative side 0.004V, battery sense wire 0.004V. I've replaced the belt, perfected tensioning it to 120Hz, replaced the battery. The crank pulley to Alternator pulley is a 2:1 ratio which means at idle it spins slower than my alternator guy can test (his min speed is about 3000rpm). However, despite the ratio, when the Voltage begins to drop even driving the car at 4000rpm's doesn't get it above 13V.
I even bought a Transpo IN220 regulator for cheap and tested it, but got the same results.
BTW, battery light still illuminates at key on and then turns off when vehicle is started.

I have ordered a new Denso 126000-0400 regulator, but haven't received yet. I'm in doubt it will help.

I've been fighting this for a month now, I'm out of ideas.
Any ideas to throw at me?
Thanks for the help.

Mark

 

Forgot to mention that. Yes, they did replace the brushes with Denso OE ones. Slip rings would be on the rotor, correct? The rotor was not replaced, they said it looked fine.

I've had more thoughts on my problem. My rectifier wasn't replaced because they said it was fine. I didn't question it because I figured a diode is either good or bad. However, due to the fact that my problem is regulated voltage dropping when warm (10 minutes), the regulator can't theoretically cause that problem.

The rectifier maybe could cause low voltage? Not sure, stretching my brain. Thinking I might order the new INR739 RN-04 rectifier (mine's the small body 90A ND).

I did test the system for A/C voltage when it was warm, but found none. That was what I was taught is a sign of a failing rectifier. Maybe not always though ...

 

Mark, where did you measure the .13V voltage drop? That seems excessive to me. If you measured that on your alternator output wire to the battery I would suspect it is causing or contributing to the problem. If you have any suspicions whatsoever about that wire I'd suggest making up a temporary wire to supplement the original and see if that solves the problem.

Way back in the dark ages ('70s and '80s) it was common for European cars to come to this country with larger alternators than were fitted in Europe, but the output wires were not upgraded to match the alternators. Lots of odd charging problems could be solved by supplementing the original wire with a seperate 10 gauge lead (keep in mind these were 75 amp alternators at the most).

Just a thought, based on everything you've tried so far and the high voltage drop you listed.

Good luck and please let us know what you find.

 

Mark: Another thing to check is the condition of the harness. On my 89, there is a funky conical connector under the airbox that had white arc flash residue. Got a great replacement cable from Ricambi (150 vs 1400@ferrari). The other thing to check is bad crimps on the large cables from alt. to starter to battery. These are 30 year old cars now.
FWIW.


Jeff Pintler
89 348tb, 86tr, 99 360 3pedal, S-160 Bobcat

 

Thanks for the tips, I will check some more of these out.
I have verified my grounds and confirmed that I don't have any of these "bullet" connectors.
That's interesting that 0.13V voltage drop on the positive side might be considered bad, I will look into this more, the cable idea is definitely simple enough to do. You just run a cable directly to the battery? Or to the Starter post as original?

I recently replaced the rectifier and tried the Denso regulator -0400, but no change.

In my research I have discovered some interesting stuff. I ordered the heat shield by VIN from Ferrari and got a shield that doesn't fit, because it's for the AC Delco Alt. - which apparently is what my car possibly started with.

I started reading some of the Delco threads and found one with quite the detailed info on regulated voltage numbers that do resemble mine! They ended up finding different results with the sense line disconnected? Easy enough to do. I'm pretty sure I've read somewhere on here that there were also wiring updates to the cars when they changed to ND alt. Maybe my issue is all to do with the wiring to the regulator? But it's late tonight and I've no time to do anymore ... I'll update in the near future.

 

I'd suggest augmenting the existing wiring with a temporary 8 or 10 gauge cable running directly from the charge post on the alternator to the positive post on the battery, just to see if that changes or eliminates the symptoms. If it does you can then decide how you want to address the problem. HTH!

 

Hello all,

Here's an update on my diagnosis:
I disconnected the battery sensor wire and found that the battery light stays on, plus my problem persists.
I temporarily routed a new wire for ignition voltage to the alternator connector, but problem still there.
I then temporarily ran a new 4 gauge wire from the alternator to the starter, but the problem is still there.

At this point I'm very confident that the problem is restricted to the alternator.
I also recently measured the size of my alternator pulley and crank pulley, I found the alternator pulley is 6.5cm diameter and the crank is 13.5cm. That makes about a 2:1 ratio, usually I would expect a 3:1 ratio. I don't know what it should be though on this car.

Could someone out there with a NipponDenso alternator measure their pulleys for me?
It would just help me eliminate another uncertainty, Thanks ahead of time for this big favor!

 

Alas, it is fixed. Took some time but I have definitely mastered the alternator.

The pulley was too big.

I ordered a new Alternator from Superformance in England, the 90A small body one, along with the alternator belt that they specified was for the 90A alternator (a 775 belt).
I got the new Alternator and measured the pulley ... Voila it is 5.4mm diameter, pretty much 1cm less than my other alternator (which is now most definitely probably not original Ferrari).

The new alternator happened to have the 6mm stud on the rectifier, my battery cable and sense wire would not fit on the stud with enough clearance to get the nut on.
So I pulled apart the new Alternator to find a transpo rectifier and a regulator with no identifying markings on it, but it didn't look like Denso.
So I installed my 0400 Denso regulator and new rectifier with 8mm stud that I had already bought for the other alternator.
I also found the the 775 belt was too big and the 760 fit much better anyway.

Drove the car, Voltage started at 14.2V and once the engine got warm it settled at 13.8V. It went down to 13.2V with my headlights on, but the previous owner upgraded the headlights so that may be another issue (or even normal).

Either way, I'm calling my alternator done.

New NipponDenso 90A Alternator part# 102211-1451 K38-H
Denso Regulator 126000-0400
Denso Rectifier 021580-4850 (I'm actually currently running a Transpo unit)

Other part numbers I found in my travels:
10-3042-4 Bearing
10-2021-4 NipponDenso Internal Fan SRE Bearing
021620-2720 Denso Brush Holder fits Toyota
340-52002 90A Denso Aftermarket Stator
126000-1500 OE Denso Voltage Regulator Ferrari (I still have this regulator, but not installed, haven't found much difference between 0400 and 1500 in actual operation)
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I was able to measure the pulley on a 355 alternator, and it was 6.5cm. I suspect that someone in the past put a 355 alternator in. I often hear people comment how the 348 and the 355 aren't much different (although I know better), but that probably can lead to situations like this.

I also was told by another tech that the 355 idles higher than the 348 at around 1200rpm's. He had dealt with this in the past, but he's no Ferrari master, so who knows. But that would make up for the slightly larger pulley.

Definitely a different and odd problem, I was doomed from the start of the rebuild.

But nevertheless, it is now documented in the forums.

 

Anyone replaced an alternator on a 456M? I am about to start and want to know as much as possible, before hand. The WSM is not very helpful.

Any tips would be deeply appreciated.

Dennis

 

Have a look through this thread Dennis. There are 34 pages in total.

https://www.ferrarichat.com/forum/australia/495195-456-journey-34.html

An Aussie owner named Gezim picked up a 456 and did A LOT of work to it.

He is an Auto Electrician and owns his own business. I don't remember if he rebuilt his alternator, but if he did it will be in this thread with pics.

You might find some of the other repairs he did useful also.

 

Thanks Pap,

I will follow up,

Dennis

 

Hi Pap,

Went through the thread you passed on to me.

A wealth of knowledge. I will keep as a reference source.

Thanks again,

Dennis