Voltage regulator

[schulr]

My VR failed last summer showing voltage spikes so I removed and had it rebuilt by a highly rated shop. I asked that all replaceable parts be replaced as I was not too keen on repeating this job. Some cautioned against rebuilding but the cost difference was too great, $200 vrs ~$900 from our host.

Well you can probable guess where this is going. Returning ffrom a track day at Atlanta Motor Park yesterday, my radio started to cut out again which is a sure sign of voltage spikes. I confirmed this with my volt meter and I was spiking up to 17.

So the question, is there anything other then a faulty VR that could be causing the voltage to spike? Is it a mistake to rebuild the alternator/VR again?

Appreciate any thoughts on this

Bob

[Joe Bob]

Well, you replace a VR and you rebuild an alternator, brushes, shaft bearing etc. I am a firm believer in rebuilds at a local shop for many reasons. Unfortunately the replacement parts just aren't up to former standards. A Bosch isn't German made anymore. Hell, Brazilian parts are better than the China crap.

If the shop is as good as you say, they should replace the VR....labor however is on you.

[schulr]

Yes, that's what they did, new VR and rebuilt the alternator and I'm sure they would work with me on the price. Just a bit gun shy on going for a rebuild again. What else could cause voltage spikes or is it a forgone conclusion it's the VR again.

[wwest]

You MUST have a GOOD, SOLID electrical connection between the battery posts, both, and the alternator and engine ground.

If the battery is not "in" the circuit, or intermittently so, the alternator voltage output will go into orbit...

Check:

Connection to alternator at the starter.

Engine grounding to frame.

Battery posts have been known to fracture inside the battery.

Shorted stator phase in the alternator can result in over voltage, the other 2 phases must make up the difference, voltage at the battery will average ~13 volts but the closer you get to the alternator the more the voltage will be elevated.

Intermittent shorting in my '78, hit a bump in the road, stator phase shorts, over voltage, CDI locks up....

Took awhile to figure that one out.

[schulr]

Thanks wwest, the battery portion is good and its a new agm type. I'll do some more voltage checks and the grounds too before I start to tear down.