The alternator replacement thread, Fixed! Options

[VaccaRabite]

I have AAA gold so my tow was covered. As I gain confidence with the car and drive it further I’ll maybe up my service.

Did a test this morning with a spare VR I had.

Battery charged overnight.

With a newer VR (the one on the car last night when it failed) the Alternator light did not turn on when I put the key in.

With the old rusty “spare” the light lit up on key in, but did not turn off when the car started, even after I revved the engine.

Oh. And WHY AM I NOT WORKING ON A MONDAY you ask? Electrical storm last night took out power to the upper floors of my house (without tripping the breaker) at about 2:30 am; so now I’m waiting for the electrician to see what the damage is. At least 1/2 my House has power. :-/

[mepstein]

I hope the house is ok. We had flooding in SE PA. Couldn’t pull out of the driveway the water was so deep this morning.

[VaccaRabite]

Just did Spokes test of shorting DF and D+.
Battery went from 12.12 volts engine off to 11.87 volts engine on at idle.

If I understand correctly even at idle I should expect to see greater then 12 volts with the VR shorted to Max Effort state. I’m guess the alternator is just dead.



I also made sure the belt was tight, and it was good and tight.
Going through grounds and don’t see anything too off kilter, though I have only looked at engine bay grounds as yet.

This alternator, by the way, only had about 300 miles on it. It failed really quick.

While I’m thinking about t, is there a way to bench test the voltage regulators?

Zach

[VaccaRabite]

I hope the house is ok. We had flooding in SE PA. Couldn’t pull out of the driveway the water was so deep this morning.

I can’t find evidence of lightning having hit the house, but the crash last night was right on top of us.

I turned off the breaker for the suspected circuits so the house didn’t burn down and tried to go back to sleep.

When it rains it pours I suppose. Lol.

Zach.

[1adam12]

I have AAA gold so my tow was covered. As I gain confidence with the car and drive it further I’ll maybe up my service.

Did a test this morning with a spare VR I had.

Battery charged overnight.

With a newer VR (the one on the car last night when it failed) the Alternator light did not turn on when I put the key in.

With the old rusty “spare” the light lit up on key in, but did not turn off when the car started, even after I revved the engine.

Oh. And WHY AM I NOT WORKING ON A MONDAY you ask? Electrical storm last night took out power to the upper floors of my house (without tripping the breaker) at about 2:30 am; so now I’m waiting for the electrician to see what the damage is. At least 1/2 my House has power. :-/

I don't know man... sounds like the beginning of 'War of the Worlds'. If Tom Cruise runs by your house, you should run too! Just say'n lol

[VaccaRabite]

Electrician for the house will be here in a few minutes, but I've searched all the grounds from the cockpit back. Battery to body is pristine. Trans to body has no corrosion. Every place that grounds in the engine bay was tip-top. I need to look in the cockpit yet, but I suspect things will be good there too. The car is kept indoors and I don't have that many miles on the body since the restoration ended back in 2009/2010. If the ground that are exposed to the elements are good, I have to think the cockpit grounds will be good too.

Zach

[ClayPerrine]

Just did Spokes test of shorting DF and D+.
Battery went from 12.12 volts engine off to 11.87 volts engine on at idle.

If I understand correctly even at idle I should expect to see greater then 12 volts with the VR shorted to Max Effort state. I’m guess the alternator is just dead.



I also made sure the belt was tight, and it was good and tight.
Going through grounds and don’t see anything too off kilter, though I have only looked at engine bay grounds as yet.

This alternator, by the way, only had about 300 miles on it. It failed really quick.

While I’m thinking about t, is there a way to bench test the voltage regulators?

Zach

A Bosch alternator is a B circuit alternator. That means that applying 12v to the field (DF) terminal on the alternator will make it provide maximum output, somewhere in the neighborhood of 15 to 18 volts. You should also hear the whine come from the alternator and an RPM drop on the motor.

Zach.. check and make sure the relay board is not the culprit. Pull the 3pin alternator plug off the relay board, and with the car running, apply 12v from the battery positive post to the DF terminal. If you don't get 15 to 18 volts and a whine, I would replace the alternator and the wiring harness to it. There is a group sale on the harnesses going on right now in another thread.

Buy a new Bosch alternator. A lot of the "rebuilt" alternators out there are just cleaned and maybe replace the brushes.

[914_teener]

So was a battery charger plugged in and hooked up to your car when the lightning struck?

[VaccaRabite]

So was a battery charger plugged in and hooked up to your car when the lightning struck?

Yes, but the garage seems to have escaped unharmed.

Electrician is here now, and power is restored to the entire house. A bathroom GFI outlet died though and requires replacement.

Zach

[VaccaRabite]

A Bosch alternator is a B circuit alternator. That means that applying 12v to the field (DF) terminal on the alternator will make it provide maximum output, somewhere in the neighborhood of 15 to 18 volts. You should also hear the whine come from the alternator and an RPM drop on the motor.

Zach.. check and make sure the relay board is not the culprit. Pull the 3pin alternator plug off the relay board, and with the car running, apply 12v from the battery positive post to the DF terminal. If you don't get 15 to 18 volts and a whine, I would replace the alternator and the wiring harness to it. There is a group sale on the harnesses going on right now in another thread.

Buy a new Bosch alternator. A lot of the "rebuilt" alternators out there are just cleaned and maybe replace the brushes.

I'll check it, though it will be after the electrician for the house leaves.

I bought the alternator and VR Bruce had. Its rebuilt but by a local guy that he trusts to do it right. If Bruce trusts it, so do I.

Zach

[ClayPerrine]

A Bosch alternator is a B circuit alternator. That means that applying 12v to the field (DF) terminal on the alternator will make it provide maximum output, somewhere in the neighborhood of 15 to 18 volts. You should also hear the whine come from the alternator and an RPM drop on the motor.

Zach.. check and make sure the relay board is not the culprit. Pull the 3pin alternator plug off the relay board, and with the car running, apply 12v from the battery positive post to the DF terminal. If you don't get 15 to 18 volts and a whine, I would replace the alternator and the wiring harness to it. There is a group sale on the harnesses going on right now in another thread.

Buy a new Bosch alternator. A lot of the "rebuilt" alternators out there are just cleaned and maybe replace the brushes.

I'll check it, though it will be after the electrician for the house leaves.

I bought the alternator and VR Bruce had. Its rebuilt but by a local guy that he trusts to do it right. If Bruce trusts it, so do I.

Zach

If you were close to me, I would give you one of the 8 known good alternators I have sitting on a shelf in my attic. They all have wiring harnesses and the metal air deflectors installed.

[VaccaRabite]

So, new alt, VR and harness are all on order.

Hopefully this weekend I'll be able to start putting on new parts.

I guess to fill the time I could start working on the front of the car. I have a headlight bushing kit my car desperately needs, as well as putting the surrounds back on.

Ass of the car is up in the air, so I could go and pull the tin and the old alternator too. Just get everything ready to go.

And I suppose I could start hooking up the cabin gauges again. You know, so I'd know next time when my charging system is about to take a dump on me.


Zach

[90quattrocoupe]

Nothing to do with the car, but if your GFI plug going bad takes out the whole circuit, then it is wired in series.
The cheap way to wire a house is to wire it up in series. This takes less wiring and less time.
The proper way is to wire a circuit in parallel. A lot of electricians don't want to take the time to put pig tails on the plugs. They just wire up the plugs so the circuit goes through the plug. If a plug goes out, it takes out the whole circuit.

Greg W.

[914_teener]

Check the ignition switch.

[VaccaRabite]

Tonight I put the new alternator, harness and VR in.
The red GEN light shone bright red at key in and turned off as soon as the engine started.

So that’s done, and initial results are promising.

At idle (about 1000 rpm) the battery was showing 12.89 volts (measured at the battery using a multi-meter) and RISING. I did not test amps. Is that about what I should expect to see from the alternator measuring voltage at the battery while at idle?

Haynes is saying 14 volts (mean) at 2200-6000 rpm, but I don’t know where they were measuring that. I guess I should test again tomorrow at a higher RPM. THATS what I get for looking at Haynes after I do the test.
Zach

[Spoke]

12.89V at idle after the engine is warmed up or right after the engine started?

What is the voltage at higher revs?

Above 12.6V is good since the system is charging the battery. The voltage should be 13.5-14.0 at higher revs.

[VaccaRabite]

12.89V at idle after the engine is warmed up or right after the engine started?

What is the voltage at higher revs?

Above 12.6V is good since the system is charging the battery. The voltage should be 13.5-14.0 at higher revs.

Right after the engine started.
I only ran the car long enough to start it and measure voltage. Car was on maybe 2 minutes tops.

Zach

[Spoke]

It sounds ok so far. How many times did you rev the engine? That's when the alternator and VR will reach peak efficiency. As soon as you start the engine the battery has been weaken by the load of the start and the alternator+VR usually are running at low RPM during the start. A measurement at 2-3K after a minute or 2 warm up will let you know how the alternator+VR are working.

12.8-13.1 is good just after the start with low revs. Should increase to 13.25-14V when revving the engine.

[VaccaRabite]

System still isn’t charging right.
I drove the car to the gym, and then around. Maybe 7 miles. Pulled into the house and got the mutimeter out.
At idle I was showing 12.12 volts across the battery terminals.
Revving the car to 3k and I was showing 12.06 across the terminals. I should be seeing more at rev.

Grounds are good
Alternator, voltage regulator, and voltage harness are all replaced. Gen light is acting like it should.
I shorted D+ to DF and the engine loaded up and I saw 15 volts bear idle.

So what’s next?
Relay board?
New VR still suspect?

Zach

[MarkV]

A fully charged car battery should be 12.6 volts so I would say that if you have less than that at idle you are running off the battery.

A normal working charging system should read 13.5-14 at idle.

Do you have a known good VR you can try?

Doesn't make sense that the board is bad if you can jump the VR leads and get it to charge.

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