Alternator, voltage regulator, and Alt/Gen warning light issues

[fpshayley]

I am having an alternator charging and gen/alt warning light issue. Background: It is a 65’ Corvair engine in a 74’ VW bus. I’m not sure it was ever charging correctly since I bought it. Probably not, because I took a look at the wiring and there were problems. One of them being that the gen fan warning wire was cut completely clean.

I end up with a new alternator (delco remy from Clark’s), voltage regulator (also Clark’s the cheap one), and new wiring. Gen light turned on when I turn the key to the on position (had never seen it on before, so improving). Unfortunately, it stayed on when I started it. Checked with volt meter and it was not charging. Took vehicle to a shop at this point. They told me the alt was no good. Hard to believe since it was new from Clark’s. I had them take it off and I took it somewhere to test off the vehicle. It was good. Mentioned to shop I thought grounds were no good. Not sure if they cleaned/grinded the ground contact points on chassis before or after this point, but they said they went through 4 regulators that didn’t work including the new one I bought. The 4th cheapest one finally allowed a charge, however gen/alt light was still not going out and they sent me on my way. Got home and tested right away. It was charging, but over a handful of seconds was climbing from 14.3 volts up to 18 volts (!) and then would quickly drop to -1, and then it would do that cycle all over again. Looked like a lot of jumping around.

I need help figuring out what this could be. Don’t want the light not working correctly, and I thought the charge was supposed to read a consistent volt reading (ideally around 14.3) just idling. Not jumping all over the place.

Here is the wiring diagram I followed with a couple differences:

Difference 1: The wire going from Alt + > starter > battery + in diagram… I have it going directly from Alt + to battery +. It’s my understanding it doesn’t make a difference (everything else works fine that I can tell - oil warning light at least, bus turns over and runs). That’s the way it was when I got it and it runs so didn’t want to change too much.

Difference 2: I do not have a ballast resistor at all between #3 on reg, coil and term 15/54 (ignition switch). No resistor there when I purchased. Currently coil is Pertronix flamethrower II (.6 ohms), so it needs 12v. Therefore no resistor needed I believe. Correct me on anything if I am misguided. Right now I have #3 is going directly to the coil. I also believe the ignition switch wire is connected directly to the coil as well. The wire I think is the ignition wire is in the same sleeve as the oil warning light wire. I don’t know it’s that wire for sure, but that’s all I can figure.

Difference 3:
My bus has a push to start, so I don’t crank with the key. Only to turn on. I’m not sure this makes any difference at all with how the circuit works, but including all info I can think of. I am assuming that black wire on the coil goes to term 15/54 on the ignition switch. Mentioning this as I’m wondering if it could be the setup under the dash that could be causing the problem? Have never taken that apart and hesitant to do so.

A couple questions:

I have read about how the gen light works. It gets 12v from one side, which turns it on, and when you start the voltage from the other side essentially “cancels it out” and turns the light off. I see one blue wire going in the back of it. Near it is black spade wire connect next to it, connects to the equivalent other side of the instrument cluster, and to the fuel gauge. That all should connect to fuse 11. Don’t see issues. Read somewhere it it needs to get 4v back fed from the speedometer. Can’t see what is going on behind that really, but speedometer works. Front of bus is all VW wiring, so Corvair folks may not know about any of this, but curious how it works in the Corvair as it might lead me in the right direction.

Is the tab under the voltage regulator for a ground wire or a condenser? I have read both. Regulator is grounded from the case to clean metal on the chassi anyway, but let me know if I should not use that tab as a ground.

Could this be a blown fuse? Wouldn’t anything connected to that fuse not turn on if so? Only issue I’ve had on the dash is the fuel gauge wags, and of course the alt light. Everything else is fine.

Any thoughts on the light and charging issue are greatly appreciated. I’m at a complete loss especially when even the shop couldn’t figure it out.

[cnicol]

One thing I see is misconnection of regulator terminal 3 "battery sense"
This one should go to battery (+) junction block or post. I could go on as to why but more simply, it matters where it gets its 12v.

[Richard]

Regulator on the right is the original styl Reg with relays. The Reg on the left is the newer Semi-conductor style.

The tab under the Reg is attached directly to Reg terminal #4. Terminal #4 is the Exciter Circuit connecting to the Gen Light and Ignition Switch.
DO NOT GROUND THIS TAB.
The Gen Light should have a 10 Ohm, 10 Watt resistor in parallel with it.
GM used a resistance wire built into the under dash harness. In most cases they actually connected one end of the resistance wire to the Acc terminal on the Ignition switch , but it can be connected directly across the Gen Lamp.

Regulator terminal #3 should not be connected to any part of the Ignition system. The purpose of the Voltage Regulator is to determine what the battery needs and adjust the Alternator output accordingly. The wire from Reg terminal #3 to the battery is called a Sensing Wire. This wire should be connected somewhere near the battery, to best "sense" what the battery needs, but GM didn't always do that.

You said, " Regulator is grounded from the case to clean metal on the chassi anyway, ". As long as the body of the Alternator has a good ground connection to the Alternator.
With engine running, Alt charging, connect one voltmeter lead to Regulator body and other voltmeter lead to Alternator body. A good ground should produce a voltage of 0.0 Volts. An Ohm meter is not the best way to check grounds.

The last image shows a resistor added directly across the lamp on a Internal Reg Alternator wiring. Pretty much the same as the External Reg Alternator wiring. Both have Charging wire, Sensing wire and Exciter wire.

[66vairguy]

Some good comments.

Whenever someone adds an "alternator" to a non-Corvair I suggest going with the "internally" regulated 10SI body bolted to the Corvair's unique 10DN front alternator frame, fan and pulley. This simplifies the wiring and and rebuilt 10SI alternators are still readily available. Finding a rebuilt Corvair 10DN with the external regulator is getting more difficult.

NOTE: the old style electro-mechanical external regulator replacements have a bad reputation due to "cheap" construction. The newer electronic style external regulator is recommended. Of course if you go with the internally regulated conversion you don't need the external regulator.

Many examples and discussions on how to convert a 10DN Corvair alternator to a 10SI unit on forums.

[joelsplace]

Also a lot of the new electronic regulators tend to not operate the light properly from what I've heard.
Your voltage fluctuations are an issue. They can't fluctuate below battery voltage like you said so I'm thinking your meter is bad or has a low battery.

[Dennis66]

I had that problem with a "new" solid state regulator not causing my light to come on (key on / engine off). I switched to an old regulator (from a '68 Buick) and it works fine now. The relay contact that grounds the light obviously isn't in the newer regulators. Dennis

[66vairguy]

I had that problem with a "new" solid state regulator not causing my light to come on (key on / engine off). I switched to an old regulator (from a '68 Buick) and it works fine now. The relay contact that grounds the light obviously isn't in the newer regulators. Dennis

Yes I've read that some of the solid state regulators don't work the warning light, but others do. Supposedly the solid state regulator from Clark's works O.K. Anybody here who bought the Clark's solid state regulator???

I'm just glad the 10SI conversion is a low cost and practical solution. That said I should probably buy a few 10SI regulator boards and other alternator parts. As I reminded a buddy back in the 70's "You should buy some spares because new cars are changing and these parts we take for granted will be gone.

[Dennis66]

I went through that with Isuzus. When I had them back in the late 90s to around 2015, parts were plentiful. The boneyards had plenty and prices were reasonable. Now, that has pretty much dried up, and boneyard prices aren't much below buying from Ebay. Dennis

[fpshayley]

Thank you everyone! I moved the terminal 3 wire off the coil and onto the battery + post. Also took that ground i had on the tab underneath off. Working great now! Steady charging voltage, and the light goes out after start.

I have one other unrelated problem. Let me know if I should just create a new topic. I don’t believe it’s the gas pedal spring sticking, but when I put the gas on and release it will stay reved up higher than idle a lot of the time. Sometimes it will fall back down slowly. Can get it in a better spot sometimes if I pull up on the pedal a little with my foot, but it feels like it’s sprung back up all the way. Any suggestions on what I should be looking at that may cause it not to fall right back to idle?

[cnicol]

Good job on the alternator repair!

[Dennis66]

The "not returning to idle" could be linkage, or it could be a vacuum leak. Have a good look at the short hoses that connect the balance tube to each cylinder head at the bases of the carbs. Hoses should be connected, soft, and not cracked. Easy to replace, often hard from age. Then the small hoses going from carb base to choke diaphragm and choke diaphragms too. The diaphragms (usually the plastic housings) get brittle and can crack from age. Distributor vacuum hose, if automatic trans, there will be a hose connecting to the balance tube, and a small diameter metal tube running to the transmission and another short hose connection to the vacuum modulator on the tranny. The modulators can leak too. Dennis