The alternator replacement thread, Fixed! Options

[904svo]

Made sure you have the correct bulb (not a led ) in the gen lamp socket. Since
this bulb supply the voltage to make the generator work correctly a wrong bulb will
cause strange things to happen.

[VaccaRabite]

Made sure you have the correct bulb (not a led ) in the gen lamp socket. Since
this bulb supply the voltage to make the generator work correctly a wrong bulb will
cause strange things to happen.

I know about the GEN light bootstrap. That light is correct.

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.

I need to find the other two voltage regulators I have and test them. I hope I did not toss them away Saturday/Sunday while doing the alternator replacement.

I know its working better. Before when I did the D+ to DF test there was no load on the engine or anything. Changing the alternator HELPED but I don't think it fixed everything. And I'm concerned there is an underlying issue that killed the alternator. It may well be the VR.
Zach

[Robnxious]

I just got done running this issue down as well myself. While the Alt light would go out when I started the car and revved it, and it SEEMED like it was charging, it wasn't until I replaced my VR that I was able to get the alternator to start correctly charging the battery. I ended up getting a Hella replacement, which is a bit smaller, though it doesn't look like this

https://www.amazon.com/gp/product/B01LT7E5R...=UTF8&psc=1

[MarkV]

Years ago when I thought my mechanical VR was going bad I replaced it with one similar to this:

https://www.ebay.com/itm/Auto-Tune-PT825-Vo...DkAAOSwUrdZdz~6


It is solid state and the electronics are potted. There is a short pigtail and the VR mounts where the screw for the mechanical VR mounts. I think they make an ajustable one as well.

[MarkV]

Adjustable:

https://www.ebay.com/itm/NEW-ALTERNATOR-ADJ...9!US!-1


That one might be for a 6 cylinder?

[VaccaRabite]

I bought one of the solid state pig-tailed voltage regulators off Amazon. Costs a little more but will be at my door wednesday.

By sheer force of will, this will work. I don't want to buy a new relay board. I am worried though that I've now had 4 VRs for this car. I think they have all been the mechanical points type though, and I know mine was ancient. The one from McMark was newish, but may have been damaged by the failing alternator. I don't know what to say about the NOS mechanical one from Bruce.

And if this new one does not work, I've got to assume an issue with the relay board itself, and not the VRs fault at all.

Zach

[plas76targa]

Zach, This issue was the first ‘problem’ i experienced with my 914 soon after buying it in 2005. After all the tests, try several VRs, I put a WTB in the adds and Gerald sent one au gratis. [i was for ever committed to 914 world]. Try a different relay board.

[VaccaRabite]

Well, the new solid state VR did nothing.
I am forced to admit the issue MUST be with the board.

(IMG:http://www.914world.com/bbs2/uploads_offsite/c2.staticflickr.com-1435-1534977902.1.jpg)

Though it is probably folly, I am going to attempt to rehab the board. I have a feeling this board has been the death of 2 alternators and probably other gremlins that have plagued me and McMark and the others who have helped withthis car over the years.

When I took the board off there was already evidence of a previous "repair" where someone had taken the potting off around the VR plug and soldered something down. I'm going to clear all the potting and start from new.

Because I'm stubborn. And I want to drive my car maybe this weekend.

Its frustrating as the car seems to be charging at idle. I had a meter on the battery for about 15 minutes and the battery went from 12.25 volts at start to 12.54 volts after a few minutes.

But as SOON as the engine revved to about 3000rpm, the battery fell to 12.01 and bounced around on the meter.

If I can't find an issue on the board by Friday, I'll suck it up and put up a post for a new board.
@spoke
Zach

[904svo]

With the engine running measure for voltage between the alternator body and the engine case if you measure any voltage you have a grounding problem with the alternator and the engine case with the bolts hold the alternator in place

[Spoke]

While you have the relay board out, measure the resistance between the D+ to D+, DF to DF to Pin 2 of the cabin connector, and D- to D-.

You can see by the schematic below that the relay board doesn't do too much for the alternator except provide a place to mount the voltage regulator and provide a wire back to the dash for the GEN light.

You shouldn't be killing alternators that easily. Check all grounds and the transmission strap. When you had your engine out you didn't paint or powder coat the fan shroud? The alternator is grounded to the shroud and the only direct ground connection to the engine case are the 4 little studs attaching the shroud to the engine. The tin might also provide some grounding but it's really those little studs providing the most grounding.

[mepstein]

Well, the new solid state VR did nothing.
I am forced to admit the issue MUST be with the board.

(IMG:http://www.914world.com/bbs2/uploads_offsite/c2.staticflickr.com-1435-1534977902.1.jpg)

Though it is probably folly, I am going to attempt to rehab the board. I have a feeling this board has been the death of 2 alternators and probably other gremlins that have plagued me and McMark and the others who have helped withthis car over the years.

When I took the board off there was already evidence of a previous "repair" where someone had taken the potting off around the VR plug and soldered something down. I'm going to clear all the potting and start from new.

Because I'm stubborn. And I want to drive my car maybe this weekend.

Its frustrating as the car seems to be charging at idle. I had a meter on the battery for about 15 minutes and the battery went from 12.25 volts at start to 12.54 volts after a few minutes.

But as SOON as the engine revved to about 3000rpm, the battery fell to 12.01 and bounced around on the meter.

If I can't find an issue on the board by Friday, I'll suck it up and put up a post for a new board.
@spoke
Zach

If you need another board, just pm me your address. I have a good one you can have $n/c. If I send tomorrow, you should receive Saturday.

[VaccaRabite]

While you have the relay board out, measure the resistance between the D+ to D+, DF to DF to Pin 2 of the cabin connector, and D- to D-.


You shouldn't be killing alternators that easily. Check all grounds and the transmission strap. When you had your engine out you didn't paint or powder coat the fan shroud? The alternator is grounded to the shroud and the only direct ground connection to the engine case are the 4 little studs attaching the shroud to the engine. The tin might also provide some grounding but it's really those little studs providing the most grounding.

I did in fact powder coat the shroud and tins. That could be it.
I’ll run a ground wire from the alternator bolt to the engine case.

My other grounds are all golden. Trans, battery, and wire harness all made solid connections. I did not know about how the alternator grounded though.

Zach

[VaccaRabite]

If you need another board, just pm me your address. I have a good one you can have $n/c. If I send tomorrow, you should receive Saturday.

Mark. Yes please! Pm sent.

Zach

[Spoke]

I did in fact powder coat the shroud and tins. That could be it.
I’ll run a ground wire from the alternator bolt to the engine case.

My other grounds are all golden. Trans, battery, and wire harness all made solid connections. I did not know about how the alternator grounded though.

Zach

If you didn't scratch off the powder coating from around the shroud mounting studs, the alternator not being grounded is a possibility. A grounding wire from the alternator case to the engine case is a good idea. Before you do this measure the resistance from the alt case to engine case. It should be zero ohms. Use a heavy wire like the one going from the alt to the starter.

There was another 914 owner who had charging trouble and also realized the accelerator cable was getting hot. It turned out the alternator was grounding through the cable.

[VaccaRabite]

I got Epstien's package in the mail today. So that was a good excuse to fiddle with the car after work.

I tested continuity from the alternator to the engine block and to the body. Very strong continuity, about one ohm resistance from the alternator case to the body. From the transmission to the body was basically zero resistance (there was a very small number on the screen of my meter). So, gounding was not an issue.

I replaced the board with a new one from Mark and put everything back. I am using the new solid state VR.

Started the car, and was measuring 12.6 volts at the battery on the meter at warm idle. Unplugged the VR and it dropped to 12 volts on the battery, and the engine idle speed increased slightly. So the car IS charging at idle.

Bring the throttle up to 4K rpm, and voltage dropped to 12.05 volts. So back to its old tricks. With all my lights on (driving lights, head lights, flashers) and the engine at 4K rpm I was only making 11.3 volts at the battery.

Unplugged the VR again and shorted DF to D+ and was making 14 volts at idle and the engine idle lowered noticeably.

I had my laptop plugged in and talking to the ECU, and the ECU is seeing about .6 volts less then my meter is seeing across the battery terminals. The tuning software was occationaly flashing the red "charging" flag.

At this place, I have replaced:
Alternator
VR (several times)
relay board
Alternator harness

I have confirmed that all the engine compartment grounds are in good shape.

About the only thing I can think to do at this time is add a ground wire from the alt to the engine case, but I really doubt that's my issue at this point. :-/

The other option is a bigger alternator (70 amp maybe?).

Is it at all possible that my battery is the issue? I'm using a Odessey race battery.

Thinking out loud. Is it at all possible that the alternator I put in (that I got from @bdstone914 ) was internally regulated? Would double regulation do what I am seeing? How would I tell?

@spoke
@ClayPerrine

Zach

[VaccaRabite]

EVERYTHING seems to be pointing to the voltage regulator. But I've tried three of them now, and they have all acted the same.

I double checked belt tension on the alternator and I can push it in about 1/2 inch, which IIRC was the right tension. I'm not hearing any belt squeal or squeaks at speed, just healthy engine sounds.

I guess I could look for an adjustable VR and turn up the output. I SHOULD NOT need that, but if it works....?

Edit: I just bought an adjustable VR. Hopefully I'll be able to dial in a little bit more output.

Zach

[MarkV]

Well I am stumped. (IMG:style_emoticons/default/confused24.gif)

Idle at 12.6 volts is barely charging a fully charged battery should have 12.6 volts with the engine off. At an idle is should be 13 or more. I would be tempted to start from scratch and clean all of the grounds and terminals. Clean the battery terminals to bare metal. I run a heavy negative cable directly to one of the engine to transmission bolts. It could be that something is working barely at an idle but falls off under any kind of load.

[904svo]

just a WAG try cleaning fuse #9 (both sides) this supply the voltage to excite the
alternator if its dirty it could stop it from charging.

[Spoke]

one ohm resistance from the alternator case to the body. From the transmission to the body was basically zero resistance (there was a very small number on the screen of my meter). So, gounding was not an issue.

If you're measuring one ohm between the alt case and engine block, this should be considered a very large resistance. If indeed you have 1 ohm resistance between alt case and engine block, this would account for strange behavior and not as much voltage applied to the battery.

Ohms law is V = I x R. With 1 ohm if there is 1 amp of charging current, there will be 1V drop in a system where the difference between 1-2V is huge.

You can test to see if you have a voltage drop from alt case to chassis by measuring at the VR from D- to chassis. See the schematic below where D- at the VR is connected to the alt case. Short D+ to DF; start the car and measure voltage from D- to chassis. There's a chassis stud right by the relay board. You should read zero volts or near there.

[McMark]

I can't remember...

Is your alternator harness new?
Battery positive cable?
Battery?

You can also attach the VR directly to the alternator harness, bypassing the relay board, BUT you'll have to add a jumper wire to bootstrap the alt and make it charge.

Another aspect is that a dead/dying battery won't take a full charge, and that can look like charging issues.

Oh and I have the distinct impression your car has a curse on the electrical system.