How To: Upgrade the regulator & rectifier on the 355 alternator (with pictures)

Nice.

I like how you show how to press out the old bolt.

One other thing.

I'm guessing you didn't have any problems fitting the new rectifier? The reason I asked is because a couple of guys found that the back cover on their alternators was smaller in diameter, and thus the rectifier could have arching going on due to the screws touching the cover = no good.

 

Was that only on the 348's, or was that with 355's? No problem on my 1997 355 spider (5.2 Motronic).

 

Well done! Two things I might add:

1) This can be done sucessfully "in car"...I did it that way. Just need a right angle #1 Phillips screwdriver.

2) You made no mention of the rubber cover for the center brush assembly...mine was in fact stuck (probably from the heat) to the metal cover. It was not until after the job was done a few days later that I worried about if mine was missing...put it back on the lift and removed the cover and there it was.

BTW, has anybody been able to determine the correct part number for the brushes. Though mine were only 25% worn, it would have been great to spend the extra $10 and replace them as well. I tried at a local Romaine Electric wholesaler/rebuild shop, and they could not match it up.

 

Ya know I don't remember exactly?

But I do know that there are different Nippondenso alternators used on the 348/355. Why? Because there are two different belts. One alternator is a 90amp and the other is a 105amp. The 105amp alternator has the smaller belt

Here is what I wrote on page 8 of my alternator rebuild thread: http://ferrarichat.com/forum/showthread.php?t=142329

I don't remember if we ever figured out how to identify if you have the alternator with the smaller 103mm rectifier??

 

Just went back and had a reread of page 8.

Georg's Nippondenso alternator was #101211-5070. So it could be that those are the alternators that are running the smaller rectifiers? I haven't ever looked for the Nippondenso number on my alternator to compare.


Say Hack.......

How come you didn't post the pictures of you rebuild in this thread???? I think you should.

 

Exactly ! Alternators 101211-5070 or 101211-5071 are the small ones with 90 Amp and the 103 mm rectifier, # 101211-7580 is the big one with 105 Amp and 113 mm rectifier.

Regards, Georg

 

Right on Georg! Thanks for clarifying that.

 

See the little two hole metal piece below and to the right of the rectifier laying on the table near the nut in this photo? Can anybody tell me where this goes?

Thanks

Dave
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If I'm looking at the correct piece, it goes on the outside of the cover. It gets held down by the middle nut and screw. You can see it in this link. http://ferrarichat.com/forum/showpost.php?p=136541812&postcount=13

 

Hello, I have a 348, but should basically be same as yours. Here's a pic that shows where mine went.
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Thanks for that. Does it have a purpose? right now the alternator is generating 14.05 Volts steady state and charges the battery just fine, but the red battery light on the dash doesn't go out. Does it have anything to do with that? I've duplicated all the ground connections trying to make the light go out and its still on. I've checked the red wire at Battery and its making connection.

any suggestions?

 

Check your negative connections, and the ground wire to the frame from the alternator.

 

Check the "sensing" wire that runs parallel to the main positive cable.

And when I say parallel, I mean the red 12 gauge wire is bundled adjacent to the main positive wire all the way to the front of the car, and is finally connected in the lead battery terminal itself. If the terminal is changed, and this is overlooked, the system works sporadically.

JM3

 

BUMP - We really need to determine the numbers for the brushes, rotor and stator for both the 348 and F355 alternators. I've tried, but hit a wall. Anybody have better luck? It really seems a shame to "re-build" the alternator without replacing these inexpensive parts to do the job correctly.

 

I already suggested that and he checked on Sunday and found the wire had already been updated with a ring mount and fixed to the postive battery clamp securely.

 

I have duplicated all possible grounds and am now thinking I may have damaged the bundle of 3 wires that leads from the alternator and terminates there with the green 3 prong plug. During the alternator removal from the bracket I noticed I damaged the main power cable rubber protective material using a crowbar to remove the alternator which was snug in the lower two prong mount. I inspected the power cable and it seemed fine. Since the bundle of three wires was right next to it eventhough it didn't appear to be touched it may have been inadvertently severed internally. If I severed it internally (impossible to get to now that i have reinstalled the oil tank and the headers) is there a way to identify which of the three wires on the plug is the sense line? and is it possible to home run that wire to the battery to turn the "battery" light out in the dash? I will be able to properly repair the bundle if that's what the problem is at the next 30K in 5 years but I don't want to stare at that red light for that long.

Thanks for your advice

 

In talking with Earnie he seemed to think the 3 Wire bundle coming from the Alternator 3 prong plug actually follows the front of the engine then turns back into the engine valley. He seems to think it can be removed and repaired with removal of the air induction system and snaked up so that it could be repaired if its is damaged. Does anyone have a schematic or drawing depicting this wire bundle? or the wiring diagram that shows the sense wire and where it terminates.

Thanks

 

Dave and I were talking over the phone and I was trying to explain to him how to remove the wiring loom for the alternator. I also suggested that he see if one of you guys has the wiring diagram for the 355, 5.2. That way he can trace back the wire from the alternator to the light in the dash board. Basically take the guessing game out of what wire goes where.

So............do any of you guys have a wiring diagram for the 5.2?

 

Here check it out Dave. I was having a look at the wiring for the alternator on your car on Daniel's site. http://www.ricambiamerica.com/parts_catalogs.php?M=FE&P=&V=diag&I=1495

The main power cable does lead back to the starter and then to the box. But what I didn't know what that it t-ed off tot he starter. I'm still trying to find something for the plug that goes into the back of the alternator. There is also a little wiring coming off that main cable, before it gets to the starter. I think that's the one jm3 was talking about. Could you have forgotten to hook that up?

 

Ernie,

I only unhooked the 3 wire bundle at the alternator to rebuild to rebuild the alternator. All wires aft remained untouched. There is a single wire that comes from a power lead bundle to the starter but not sure where the other two wire dissapeared to.

Thanks,

Dave

 

I'm still stumped as to where the 3 wire bundle that plugs into the back of the alternator goes. I believe I have a broken wire in the sense line which is turning on my Battery Light on the dash. Can anyone who knows for sure advise?

Thanks

Dave

 

If I remember correctly it comes off the main wiring harness, at least on my 348 anyway.

 

Which of the three pins is the sense line that turns off the "Bat" Warning light on the dash????