355 alternators suck!

Mine just failed, too, a Denso, after a few thousand miles following a rebuild. A buddy with another F355 went thru 5 alternators in 2 years! He finally sold the car after the alt. failed going to Monterey for the last Concorso.

I'm working with a few engineering types (including one from Denso who shall remain anonymous) on a solution, and should have some preliminary results in a few weeks of testing. Stay tuned.

We're data gathering, the more info from the more F355 people, the better. Can you tell me anything about the way yours failed; for example:

* was the warning light on at all?
* how many miles on it?
* ever been rebuilt or modified?
* was it the first to fail? If not, how many before?
* did it fail at cruise speeds or in-town traffic?
* Is it manufactured by Denso or __ ?

Thanks in advance,
Al

 

I don't know if this helps, but I am having the same trouble with my 348. I've owned the car for six months and it's now in the shop for the 2nd time. This alternator lasted about 2,000 miles - 6 months.

It was working fine, then I took off brining the car up to 6,500 rpms and the light came on. I had 20 minutes to get home before it died.

 

If the VR is failing, I would think you could easily install a new one outside the case that could handle the job. It wouldn't be c but you'd have a reliable electrical system as far as that goes.

The diode bridge is more problematic....

Ken

 

FWIW

i blew the VR on mine 3 years ago

no problems since but i'm holding my breathe

i keep my AAA card with me

 

After the factory suggested fix of installing ground straps the failure rate of alternators on 355's that were driven regularly (the batteries were not on a constant cycle of being very discharged from sitting then the alt was working at very high output every time the car was driven) The failures went down to almost zero.

We did have a period of time with some alt failures but that was traced to the rebuilder using cheap non OE parts.


I have not had a 355 alt failure in the shop in 1 1/2 years.

Alternator rebuild shops are not all equal.

 

#1 yes

#2 Few cars are let to sit on a regular basis until the battery is so depleated that it will just start the motor. It happens once in a while on any car but on many Ferrari's it is a way of life and no machine can be required to put out 100% that much of the time without shortening it's life.

The old Bosch alternators were not as small a package but they did seem more tolerant of that kind abuse than the Japanese units are.

 

I've been through 4 alternators on my '95 F355. All times the battery light came on. I had the ground strap added on the second alternator.
All alternators were the Denso factory unit - new.

What gives?

AZFerrari

 

I keep mine on a Deltran tender all the time.

I had the ground strap update.

Here's a suggestion - have you had a heat shield installed? The alternator bakes from the engine heat; my mechanic fabricated a heat shield. Don't have any proof that it works, but I haven't had any problems since, and it was cheap and easy.

vty,

--Dennis

 

Thats not an alternator problem any more than a gun shot wound is a lead poisoning problem.

Some diagnostics need to be done and not just replacing parts.

Don't know the failure mode but lots of possibilities. If it's a bearing failure it could be an over tensioned belt, if a diode failure it could be a polarity problem on a jump start or reversed connections on the battrey maintainer. I've seen that one on a lot of cars.

Your mechanic needs to look into the root of the problem and quit just addressing the symptoms.

 

Dennis, can you post a picture or 2 of the heat shield you had made? This sounds like a very sensible idea.

Also, can someone tell me what to look for to determine whether my car has the ground strap? Where does it connect to and from (or from and to???)

Thanks in advance, Dave

 

It is a rather heavy gage strap that is mounted in a variety of ways directly to the alternator and the oil pan.

Many were home made and that is ok but you have to keep in mind the reason for it's existance. The spring loaded bolt and the lower mount was the only ground path for all alternator output. The design was not a solid, rigid mount for vibration isolation purposes and it was susceptible to corrosion and high resistance that pevented the high levels of current to pass.

That is why the alternators kept failing.

The ground strap needs to be a heavy gage, a simple wire will not due.

 

It's pretty obvious by just looking at the alternator if you have one.
Ferrari part no. is 180904 for around $20-25.

 

All Ferrari electricals suck on every model. The problem may not be with your japanese alterantor but the crap it is connected to. Also, some rebuilders are worthless. I have success with mine over the last dozen years. I have never had a failure yet. Before you suspect a japanese electrical part susspect other systems.

 

The factory ground strap is about 8 inches long. You can buy a similar one at most automotive stores for about $6. Run a search under "355 alternator ground strap" and you will find threads with photos showing the installation/mounting points for the strap.

Though my car has about 37k miles on the original alternator, I recently bought a heavier duty ground strap. The one installed by the dealer (years ago) is made from what looks like a 12 guage wire and appears a bit "crispy", from the current load. I picked up a 4 gauge strap at the auto parts store, and will install it during the next oil change.

 

Dave,

The alternator generates a certain current when it's running. That current at the output wire (B+) is the exact same current in the frame (ground) of the alternator. If the amperage flow exceeded the capability of the heavy gage ground wire and cooked it, it certainally would exceed the capability of the smaller gage output wire and fried that, too.

So, I suggest that if your additional ground wire's insulation is crispy, it was due to either radiant heat from the adjacent header pipe or you had a connector on the wire which had some resistance.

FWIW, Al

 

Thanks for the advice folks - I'll check it out when I get home. Better safe than sorry.

Dave

 

Hey FBB how are ya? I would second that on the quality our eastern bretherns parts, its probably more about what its connected to... Japanese parts and Italian parts humm, kinda like dissimilar metals LOL. My 355C has its orginal unit on it and has had no problems...yet.., this car was raced for three years also. Regards, Vern

 

Now that is funny! Well Vern.. things are great in So Cal. Mid 70's clear skies. Damn ! No snow in the mountains yet= no skiing and bad fishing in the spring. I 99% finished my cage. Some of the critical features are a full containment seat attached directly to the roll cage. So as a result when I drive the car on the track I am bouncing all over the place. This thing is stiff and I feel every single pebble on the road. Now I need to work on dialing in the chassis since basically I feel like a 3000lb go kart with no suspension.

 

If you plate it gold and wear it around your wrist, you be blingin'.

180904 looks like this:
Image Unavailable, Please Login

 

Japanese electrics are second to none ,However I do find that many rebuild shops use inferior Chinese replacement rectifiers and voltage regularor assemblies.Insist on genuine japanese parts(Nippondenso) when rebuilt. it costs more but well worth it.

 

The alternator is the same as Honda NSX apparently.

the rectifier is the weakest link, and then the regulator is also a bit touchy now and then too...

so far, the ONLY after market parts I can find for them are made in.....

the USA.

Rectifier part number INR736

Regulator number.... oh bugger, I'll need to look it up

With the rectifier... the diodes as std have little flat strap tails with a wriggle in, and they blow like a fuse at the wriggle bit... through heat/electrical load/vibration etc. The USA built ones I use, have round tail diodes, and I haven't blown one yet (not to say I wont), and I've had them running on several 360C racing and now the 355 Twin Turbo conversion....

In repeated failure cases, I'd suspect dud parts first, heat source second, then chassis wiring problem after that.

 

It blew before the Calder track day, which was why he went home early.