1990 348 with Delco Alternator

The Delco alternator in my 1990 348 bit the dust. Luckily I was only few miles from home so I was lucky to make it to my garage. I have STFA'd and saw lots of good info but some of the material is several years old and many of the web-sites referenced do not exist or the part numbers are invalid (I would like to try to rebuild the alternator myself).

Has anyone had recent experience with this alternator and if so, care to put the info for:

1. Getting a rebuilt alternator.
2. Regulator (P/N and source).
3. Rectifier.

Thank you

 

Thank you both. I completely agree; I also suspect that the rectifier is dying due to the current load imposed by the combination of the fans, AC, lights, etc. Accidentally, the alternator failed exactly in this configuration - I was coming home late in the evening with lights on, AC on and was in traffic meaning I am sure the fans were kicking on. I suspect my battery was not fully charged as I have not driven the car for a while.

I decided to buy the DB Electrical alternator - thank you Demetrius - the 160A version should provide the extra capacity. Then I can use my old alternator for experimentation and may rebuild it and have as a spare.

 

I bought this one as read that 1992 Monaco fits. I hope this is the right one (will swap pulley of course)...

DB Electrical - ALTERNATOR HIGH OUTPUT 160 Amp 3.0 MONACO 90 91 92 EAGLE PREMIER

Will do the usual photos of step-by-step.

I think the Delco unit was a ticking time-bomb and I am actually glad that it failed close to the house as opposed when I am miles from home.

 

OK, so the replacement alternator is on the way so I figured that I should probably remove the old one in the meantime.
First, I loosened the tensioner pulley which is accomplished by undoing the bolt going through the center of the pulley. Then, I loosened the tension on the belt by turning the tensioner CLOCKWISE. Note, when you start feeling resistance STOP as the tensioner is loosened to the max distance. It was still a bit tricky to remove the belt and took some prying. I bet it will be fun putting the belt back.

The rest process is pretty straightforward; the only thing that I should mention here is that you need to remove the aluminum bracket that supports the shift cables. Otherwise the long bottom alternator bolt will NOT clear. See attached photos below where I show the removed bracket (3 nuts that hold it).
I am still trying to diagnose what failed in my unit; I suspect it is the rectifier. Also, the rear bearing on the alternator was shot so it was definitely time to get this fixed.

Now I am trying to figure out how to take the stator apart from the rectifier. I think I need to unsolder the windings next.
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Thank you. Today cleaned, repainted and re riveted the alternator shield. Check out the "home-grade" fiberglass work. I could never believe that this was a Ferrari factory part. Ferrari is not kidding when they say the cars are hand-built ;-)
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Alternator arrived today. It is supposedly a 160A version of the good old Delco alternator. Everything went back perfectly. I swapped the pulley of course as the one included was wide and smaller (more about that later). I think the key to easiest re-assembly is to start with the bottom bolt first (just insert it so it supports the weight of the alternator. Then, swing the top of the alternator in position and get the top bolt snug. Then slide out the bottom bolt and swing the alternator up as much as you can (it will only go about 1" or so at the most). This gives you little more room to slip the belt on the pulley which, even with the tensioner fully loose, is not really easy to get on. That extra 1" really helps. After the belt is on, you can insert the bottom bolt again, get everything tightened up.

I only took a short drive but my observations: it seems to charge OK although I don't think it charges well at idle. Here is my hypothesis as to why: the Ferrari pulley is larger than the one included with the alternator. This would make the alternator spin SLOWER at idle speed than designed. Which means that the field may not be excited until the throttle is advanced.
My battery is fully charged so during normal driving I was observing charging voltage around 13.5-13.7V which is a bit low but in-line what I was seeing with the old, factory alternator.

So to sum up, this model seems to work (given the $219 price it is very attractive and seems nicely built) but the idle charge is an issue. To solve this of course, one could: (a) swap the pulley with smaller one or (b) change the regulator with one which would have a lower set-point. Unfortunately neither option is very straightforward. I will try to drive with this guy for a while and see what happens. It sucks to have your battery discharge slightly at idle.
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Took some measurements with a DVM. All measurements at the battery terminals.

1. Battery resting voltage (overnight) - 12.76V - great!
2. Start-up (cold), all accessories off 14.33V - engine RPM 1200. Great.
3. Turn on the AC and lights - 13.4V - not that great but OK, I will take it.
4. Turned on the high-beams - 12.7V - borderline.

Let the car warm-up to the full operating temp.
5. 12.95V -13.2V - all accessories OFF
6. Now, turn lights, AC, let the fans kick in and I get as low as 11.9V! Houston, we have a problem.

The way I think about it is that given, say 3x1 pulley ratio between the crank and alternator a 200rpm drop at the engine (as the engine warms up) equates to 600rpm drop at the alternator!
So if the pulley size changed even slightly we can be looking at hundreds RPM difference at idle.
Hence my problem.

 

This is an interesting project. I am spending way too much time on this. Anyway, I drove the car a little more over the holidays and really pleased with the results. The voltage dips into 12V on occasion with full load at idle but under normal driving (RPMs), even with full electrical load the alternator is providing plenty of juice. I wonder whether the CS130 regulator has any temp compensation (I think it does) as the voltage seems to drop with increasing temperature.


Jeff - I am curious to find out what exactly you found out. To my understanding the CS130 alternator should have the "S" - sense connection made. Ferrari engineers did not do this and the only connection on the 4-pin plug is the L - lamp that provides functionality of the warning lamp. It is wired, through the idiot lamp and a resistor to the ignition so the lamp is on when the engine is off.

Ideally, the "S" connection on the 4-pin connector should be connected to the main bus bar - routed to the fuse block. I bet that is what the shop was talking about. So I do not think Ferrari made wrong connections, they just got lazy and skipped one wire that would be very helpful to provide bus voltage reference to the regulator vs. the internal referencing.

The other two pins are completely optional - one allows for connection of tachometer for instance (P) - Phase and the last one is a F - field monitor - diagnostics only.

Fortunately for us, Ferrari selected one of the most common alternators for the 348 - the CS130 is so ubiquitous. The problem is that it is a BAD choice for 348 as it does not take heat well and it maxes at around 100A - both issues in the 348. The good news that there are tons of cheap upgrades out there - mine is now a comfortable 160A. As for the heat, I am screwed, you would have to go to a 130D which has DUAL internal fans, better cooling design etc. But it would not fit to the existing bracket.

 

Not a bad idea, and would definitely help. I am very skeptical of the effectiveness of the Ferrari shield to be honest.
The issue with the duct approach is that it would require a completely different alternator (which would be designed to accept the ducting assembly) which means custom mounting bracket. Not insurmountable but would require having the engine out to trial fit something that would work. Just impossible to do while under the car.

 

Hey Jeff,

It is all very clear but one question: where did you connect the "S" Sense wire to? I would think, for it to be effective and based on my experience, you need to run it all the way to the fuse block up-front (since the voltage drop will be the largest from back to front). If so, could you show me/us how you ran the wire?