Voltage Regulator

The fuse to the voltage regulator kept blowing.  At first I thought that it was related to the fuse cleaning that I had recently done.  However, I eventually figured out that something in the voltage regulator had failed.

Removing the regulator isn't too hard, just a couple of nuts on the studs that hold it to the firewall.  Since this regulator had never been apart, the lead seal was still intact.

   

After removing the seal and cover, one component, a 5W zener diode (lower left), had cooked the paint put on the nut holding it in place.  These diodes are still available, so I ordered one.

I took the 330 on a couple of events, but made sure that the battery was fully charged and just drove it on the battery.

The diode finally came (shipping was held up by hurricane Irene) and replacing it didn't fix the problem.  I then measured the two large transistors and replaced one that was bad.  That also didn't fix the problem.  At that point, I called Tom Shaughnessy and had him send me an original regulator.  In fact, he sent three as he didn't know which, if any, were good.

Well, none of them worked, even the one with a 'good' tag on it.  At this point, I began to suspect the alternator.  I confirmed that I was getting power to the voltage regulator and from there to the alternator field so wiring was not the problem.

From information on a thread on Tom Yang's message board, I bought a mid-70s Ford replacement voltage regulator (NAPA #MPE VR440SB).  This requires an unswitched power lead from the battery in addition to the existing wires.  I wired this up and still no joy.

At this point, I measured the resistances at the alternator terminals and asked Lowell Brown to do the same on his 330 GT alternator.

So it's pretty clear that my alternator has a problem, probably a shorted diode which would cause the bad reading for the +B (stator) terminal.  I'm going to remove it from the car and take it to a auto electric shop which rebuilds alternators and starters.

Stay tuned for the resolution.

The alternator was showing an open circuit on the field to ground when it was tested at the auto electric shop.  Once it was apart, the problem was obvious, the same wire that had worn through several years ago had come loose again and was making intermittent contact.  It turned out that the wires wound on the rotor weren't tight to the center, which is probably why the wire came loose again.  The rotor has to be sent out to be rewound.  One of the four brushes was stuck in the holder and will have to be fixed.  So now I wait for a couple of weeks for the rotor to come back.

The alternator got rebuilt and the voltage regulator that I fixed also worked.  So everything is good.  Once everything was working, I also tested the three voltage regulators that TomS had sent me.  Two of the three were good.  I marked them accordingly and returned them with my thanks.

The alternator and voltage regulator worked well for quite a while, but recently, after the car sat in the hot sun all day, the ammeter would show a discharge all of the way home.  After the car cooled down, then everything worked normally, so the problem was heat sensitive, probably a component in the voltage regulator failing when hot.  The FCA 50th anniversary 599 tour will be coming through Seattle in a couple of weeks and my wife and I plan on joining the tour to a dinner at the LeMay Museum in Tacoma.  She, in no uncertain terms, said that we were driving the 308 unless I fixed the charging issue in the 330.  So I got out the NAPA regulator (described above) and wired it up.  It worked fine and yesterday, I drove the car to a blood drive where I volunteer.  It was a hot day and the car was in the sun.  The replacement regulator worked fine on the way home, so the problem is in the original Marelli unit.  I'm done screwing around with it, so I'm going to send it off and have modern guts put into it.  That way it will still look original, but I won't have to worry about 40+ year old components.

BTW, wiring in the NAPA regulator was straight forward.  The case is ground, so the ground (black) wire is not needed.  The field (white) wire goes on the F terminal.  The +12V (green) wire is split and goes to both the S and A terminals.  The I terminal is unused.  I didn't need to provide an unswitched 12V supply.  When I was getting my alternator checked, I brought in this new regulator to have it tested too.  The repair guy mentioned that these regulators need a good ground as a flaky one will cause them to fail.

I sent the Marelli regulator off to have the innards replaced with modern electronics.  It looks the same on the outside, but no more flaky 50 year old parts on the inside.  One thing I took off before sending it off was the lead seal on the screws.  When it was returned, I replace and crimped the seal back on.

   

Since the glove box was out for the clock repair, now was a good time to put the old/new voltage regulator back in the car.

Well, everything wasn't well with the charging circuit.  I had noticed that ammeter was always in the + side, even after the car had been running for a while and the battery should have been fully charged.  I measured the voltage and found that it would run up to ~19V when the car was revved up.  So I pulled out the Marelli regulator, put the NAPA regulator back in and sent the Marelli back to be repaired.  I quick test showed the charging acting normally.  Then I took the car on a trip to Whistler with a drive to Lillooet sponsored by the BC chapter of the FCA.  On the way to Whistler, the ammeter was showing a negative charge most of the time with brief periods of 30A charging. Given that there was some charging, it was likely to be a voltage regulator or wiring problem and not the alternator.  The car wouldn't restart at a gas station.  I was driving with a friend in his very nice 328.  So we rolled my car out of the way and bought a new battery and we continued on.

 

I had sent off the Marelli regulator before I left and received an email that it had tested out fine.  The guy who rebuilds these had three suggestion:

1. Check the 4 way block on the fuse panel that connects the +12V back from the ammeter to everything else in the car.

2. Check that all of the grounds at the alternator, engine block, battery base and voltage regulator are clean.

3. Check that the ignition switch is working properly.  In particular he mentioned that a flaky switch can cause the ammeter to bounce around.

Well, a good look at the 4 way block definitely showed some problems.  The top two terminals had the plastic around the screw melted and one wire had the insulation melted back a ways.

   

I removed an identical 4 way block from the PF coupe fuse panel, stripped back the bad insulation and re-tinned each wire.  I also notice that the new block had jumper wires on both sides of the block while the old one only had a jumper wire on one side.

I also cleaned up the grounds at the battery case and tightened the nut holding the NAPA voltage regulator which provides the ground.  I remember that the tech who rebuilt my voltage regulator mentioned that the NAPA regulator was very sensitive to a bad ground and would go bad.

Well, after doing all this, the alternator using the NAPA regulator still doesn't charge.  I had hoped that my fixes would have solved the problem, but at least, the 4 way block did need replacing so I didn't waste my time.

So I'm going to wait for the Marelli one to get shipped back to see if that fixes the problem.  Until then, I only have short drives planned, so starting with a fully charged battery and no night driving will suffice.

The Marelli regulator came back and putting it in didn't change anything.  I'm beginning to believe that the problem is in the alternator.

When the alternator died before, the outside wire in the rotor got loose and wore through where it was hitting the stator due to centrifugal force. If this happened again, that would explain what I was seeing while I was driving. When the car came to a stop and at idle, frequently it would charge, but after speeding up, particularly after shifting, it would stop. If the wire was relaxing back at an idle and making contact again and then once the revs came back up, the centrifugal force would again separate the broken ends. Now, nothing happens even at an idle, but eventually the wire would probably stay bent out.

So I'm going to pull the alternator and take it back to the shop for testing.

Well, both the voltage regulator and alternator checked out fine.  So I put everything back together and eventually found that the ground at the voltage regulator was the problem.  To prevent further problems, I captured the grounds with a star washer and two new nuts on the studs that hold the voltage regulator.  Then the regulator, washers and nuts to hold it on.  This was, even if the regulator nuts get slightly loose, the grounds will still be good.

Since I sent the Marelli regulator off for testing, I took off the lead seal and wire.  I've had this off a couple of times and the seal was looking pretty ratty.  So I took a lead fishing weight, cut it to the seal size and cut a couple of slots for the wire.  Then I crimped everything together with vise grips.  You can see the new seal and the lead weights I used.