3G Alternator

[vrinner]

On the race car I have a 3G alternator. At the dyno the voltage readings on the Megatune fluctuated between 13 and 16. According to the tuner, the MS is sensitive to voltage fluctuations and after doing a few pulls and things getting hot, we would get some missing at high rpms when the voltage increased (above 15). Never anything consistent.

First off...the 3G's have internal regulators right...I don't need an external regulator?

2nd, any thoughts on if the alternator could be causing the issues described?

[vrinner]

I also found this online...

Problems after 3G upgrade? Are you having voltage spikes or flickering headlights after a 3G upgrade using a remanufactured alternator? A potential problem could be an internal flaw in the alternator which is a pretty easy fix. The windings inside the alternator pass by a sharp ridge inside the alternator. Some companies use cheap materials to insulate these wires and some use nothing at all to insulate them. In time, vibration can cause contact between these wires and the ridge. The contact causes a temporary short which can cause headlights to flicker, stereo to cut out, etc. What is the solution? If you buy a remanufactured alternator flip it over and push the wires forward away from the alternator case using the vent holes in the rear of the alternator.

[Meotchh]

Yes, it's internally regulated.

Never seen that write up you posted, & I've never worked with a remanufactured 3g. Is yours remanufactured?

You can easily have it tested to ensure there isn't a regulator problem.

[MikeFleming]

That internal regulator is a replaceable item bolted to the rear of the alternator case - iirc the grey/black plastic thing that takes the three-wire connector to the harness. I've forgotten if that also houses the brushes. So if you suspect it's not regulating correctly, replace the regulator.

[Meotchh]

Brushes are internal to the alternator casing.

[MikeFleming]

Brushes are internal to the alternator casing. Not exactly. They're a combined part of the regulator assembly, which bolts (screws) into the back of the alt body. New regulators usually come with a new brush set.
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[Raven855]

Vince, there are several versions of the 3G alternator. There is a large frame and small frame and both of those come with several mounting styles. Both the large and small frame alternators had and early and late style charging system with the later style having "load response" built into the regulator. Load response is the ability of the regulator to compensate the charge based on demand, such as stepping on the brake or AC compressor kicking on. A chart with the different regulators is attached. LRC is load response control in the chart. There are also several sizes of pullies available with a pully from the Chevy Astrovan being the largest. There is also the possibility of running an external regulator on the 3G. The ambulances came with a combination of external regulators or dual 3G alternators. Transpo supplied the original equipment to Ford for the ambulances. The conversion can be done today using a dummy regulator on the 3G and regulator. I did this many years ago on the black Svo. It's adjustable so it allows you to vary the voltage output and has a series of 4 led lights on it so I can do troubleshooting easily. Varying the voltage is good for running differing types of batteries like the gelcell batteries. It also lets the alternator run cooler by offloading some electronic components too

As as for the info you posted, there have been many quality problems with the reman alternators and the info you posted looks like one of the older problems experienced. The MS does like stabile voltages and it looks like you have an issue going on. Tell us what you have on the alternator.

[Patrick]

Vince, do I need to pack a spare 3G for Vegas?

[vrinner]

I had bought the original alternator from PA Performance years ago. Numbers on the outside of the alternator say 20-229-12-2 12V 95A A7F5.
I had it check at Oreily's and everything checked out OK. However the problems we were having were when things got hot and had been running for a while.

I went ahead and got a replacement, remanufactured Ultima alternator. 01-0195 43225316. The case and regulator both say Motorcraft. The regulator has F77U-10316-AA. Silver/Gray case, D style connector. No other visible part numbers on it. I'm gonna put it on the car tomorrow and just verify things are running OK.

I have also since replace the battery with a new one (the old one was shot). But haven't/wont have a chance to really test out the car because I cant really drive it on the street.

[MikeFleming]

All PA Performance alternators have a lifetime warranty.


But haven't/wont have a chance to really test out t e car because I cant really drive it on the street. We just need to build a chassis dyno next year [in your back yard - garage is too small].

[brsvo]

Back yard is too nice to loose as I remember.

[MikeFleming]

Back yard is too nice to loose as I remember. True. Front yard then.