Alternator Woes

[grimlynsan]

Hi all,

 

I have a 77 260z with L28.

 

My charge light on the voltmeter was staying on all the time (it used to stay on with the key half turned and then once started the light would go off).

 

Low and behold, after a couple of days my battery went flat.

 

I figured the cheapest way to get back on the road would be to get another alternator. Dat2kman to the rescue and I have another (hitachi externally regulated) alternator. I put it in an started her up. Now the alternator is charging off the charts! the voltmeter reading is MUCH higher than before - up to 16v when engine braking in fact - it used to peak at ~14) But the light is staying on and when i turn the key off, the engine now stays on and i have to stall it to turn it off.

 

I did some more reading on viczcar etc and figured it might be the regulator that was the issue. I inspected it and found the black wire was completely melted off and fused to the others. I removed it, soldered in a new wire and tested all the wires with a test light. All good. Put it back together and nothing has changed. Same issue.

 

Any advice on what to do next? I read posts of people having the issue of the engine staying running when upgrading to an internally regulated alternator and they fix this by putting in a diode on one of the wires on the 'T' connector but as I am using the same type of alternator and retaining the external regulator I shouldn't have to do this...

 

Any thoughts? Oh, and I don't have the money at the moment to upgrade to a fancy new style alternator which is why I am trying to retain the existing regulator...

 

Thanks all,

 

Lee

[pauly_adams]

there is a black box in the engine bay (voltage regulator), I blew a fuse in mine and it done the identical thing, try replacing the fuse and putting the old alternator in. the regulator looks like this pic

[grimlynsan]

Hey thanks for the response Pauly - this thing is driving me bonkers!

 

Maybe I am missing something really stupid (given my lack of mechanical knowhow this would not be too surprising) so I am posting some sanity checking pics!

 

To recap, here is what happened:

One day, my charge light on my voltmeter doesnt turn off, indicating the alt is not charging.

A few starts later and battery is flat, confirming the light was correct!

I get a replacement alternator (pic below). I swap it in and hook everything up the same.

Now the light still stays on, and so does the car when you turn it off. But now the volt meter in the dash moves when I accelerate etc and seems to be charging the battery. It reads at the top of the dial - very high (light still on though).

I then investigate the regulator. The connection for it has the melted black wire (not sure how long been like that) and the black wire spade connector has been removed from the terminal by PO (or fell out - no idea).

I fix the black wire, plug the spade back in, reconnect. Result is same as before the repair.

I look inside the regulator, it doesnt show any burn marks and I can't see anything inside it (pic below) that looks like a fuse or something that can be serviced.

I start the car again and remove the regulator whilst running. This stops car running (although not sure what this proves).

 

Please tell me if I am missing something obvious:

 

 

[grimlynsan]

All I can think to do is to unplug that black connector from the regulator to see if that makes a difference. Perhaps it was removed for a reason. As the run on issue was occurring exactly as it is now prior to me investigating the regulator and fixing the connection though I think it must be something else. As it also wouldn't explain why the issue happened to begin with.

 

Zed community, please tell me I have done something obviously stupid!

[dat2kman]

Try charging battery overnight on trickle charger

If battery is low voltage, the alternator will work overtime, as showing on the interior guage.

The burnt wires into the regulator are a bit f a worry!

If the gauge is peaking at 16 v, the alt can burn out very quickly, the reg should be adjustable to give a digital metered output of 14.7 volts.

The fuse is a protector.

 

I'm stumped on the engine keeping running on shut down, as the alt was swapped for same type/model!

[grimlynsan]

I just put the original alternator back in, with the black wire spade connector connected (to the regulator).

 

It it exactly as it was before the operation: charge light on always, engine does not run on when switched off, no movement on the volt meter on throttle.

 

I tried it with the black spade disconnected. Everything was as above except the red light doesnt turn on.

 

I conclude from this only that the black spade to the regulator was always connected and it just fell out when I initially accessed it (prolly wiggly because it heated up so much).

 

Are you sure they are the same type of alternator? the original has a plastic cover on it whereas the replacement does not... is this just superfical?

 

Lee

[Six_Shooter]

Are you sure it's not an internally regulated alternator?

 

http://www.atlanticz.ca/zclub/techtips/alternatorswap/

[grimlynsan]

Six_shooter that is a most amazing link! Thankyou!!!

 

So following that link, they have a z and a zx alternator side by side. my original looks more like the ZX (has 'A' and 'E') whereas the image of the z alternator looks more like my replacement, which has labels 'E' and 'Bat'.

 

Not sure if that is a reliable way to tell but it is it would suggest my original alt was an internally regulated one. Pic below, can anyone tell by looking at it if it internally regulated? (it is now installed).

 

I am going back to the garage to see if any of the wires have been looped as suggested for the rest of the conversion. There is no diode installed and both of the T connections are connected at the alt. So maybe someone already converted it, for some reason left the external regulator in the car, connected, and then my alternator died 15 years later and here I am on a a very hot day trying to work it all out :-(

 

[grimlynsan]

Breakthrough! I have both alts out and I have discovered the problem - the replacement alt is internally regulated - it is an LR150 - 200. So I guess that explains why the engine runs on when i turn it off as there is no diode installed.

 

I am however concerned that the voltage output with the new alt is too high as when I had it hooked up it was bouncing off the top on moderate acceleration.

 

Maybe installing a diode will solve this too.

 

 

 

[Zedman240®]

With the two regs connected, they were "fighting" each other. If the current alt is internally regulated, unplug the factory external reg,wire in the loop and solder in the diode (in the right direction!) and it should be fine. From memory, it was the yellow wire? I have a 280 alt in mine and its been working like a charm. I also fitted a $2 ebay LED voltmeter to keep a close eye on my volts as the 240 only has a useless amp meter.

[grimlynsan]

Possibly solved!!!

 

I have the new internally regulated alt in. I have attached the wires as they were previously attached to the original alt. I followed the cable jumping instructions posted above by sixshooter (THANK YOU!!!) whereby you disconnect the external regulator and jumper the cables - no diode required - and as Bob's my uncle the beast lives!

 

I started her up and went for a drive. The light functions as it should, comes on prior to startup then goes off once the engine is on. The only thing that concerns me is that when driving the volts are very high - right at the top of the guage. I am hoping this is just because the battery was nearly flat and once the battery is charged up it will go down to a normal level.

 

Can anyone confirm if this is dangerous? (I don't have a battery charger or I would charge it up and see).

 

What I have learned:

 

1. Changing from external to internally regulated alternator is actually really really easy (if you know that that is what you're doing).

2. Attempting to wire in an internally regulated alternator in an external configuration does not work and causes much frustration.

3. If someone who claims to have failing eyesight gives you a part, you should definitely double-check the label to make sure it is the right part before trying to install it

 

Thanks Zedders for coming to my rescue yet again. My car is for now back on the road for a grand total of $40, some sweat, and a few minor lacerations

[Zedman240®]

Grab a multimeter for a more accurate reading; those zed meters arent the best for that. Should be around 13.8-14.2 Volts.

 

Well done!

[grimlynsan]

Thanks Zedman240, I am sure I have one lying around somewhere... The Voltmeter used to work quite well with the previous alt. Sure, it would dip when the indicators blinked etc but it would give a reading in the range you mentioned (where it should be!). Now that the new alt is in the reading is very high, and I wonder how I can tell what this alt is supposed to output from its internal regulator. I have googled the model LR150-200 but not found any listing for its regulated output.

[Zedman240®]

You don't want to over charge the battery; it will shorten it's life and spill battery acid all over in your engine bay.

[dat2kman]

Lee, i let you have an internal regulator Alt?

Thats now double what you paid me!!

 

If you havent trickle charged the battery (no charger!) then, yes, the Alt will do it's darndest to charge your flattish battery, hence the higher reading on voltmeter, as it charges, it will come back.

Just like the needle on a battery charger does, as it "fills" the battery.

 

[grimlynsan]

Annoyingly, I was putting off doing the external->internal conversion cause I didn't think I could do it and is the very reason I asked you for the same type of alternator as I already had.

 

If I had known I was getting an internally regulated one, I would have paid you more got a more powerful one! This LR150 is only 50 amps.

 

Apparently is comes off newer A-series engines and was found in (USA models):

 

Datsun 200SX (1978 - 1979)

Datsun B210 1978

Datsun 210 (1979 - 1982)

Datsun 310 (1979 - 1982)

Datsun 510 (1978 - 1981)

Datsun 720 PICKUP (1981 - 1985)

 

Now that the wiring is done though, I presume this means (one day in the future when I have run out of other things to upgrade) I can put any internally regulated alternator in there assuming it has the correct mounts.

 

I have been told VL Commodore RB30 alternators just bolt right in and have plenty of amps and are bosch units and readily available. I don't have any metal work machinery so I can't just go fab up a new bracket. Hence I need to find stuff that swaps in. I have found some VL alternators for sale but when I called the wrecker he told me there are three different types and do I know the one I need...

 

Can anyone confirm if alternator mount points are the same across A, L and RB series engines? Cause that seems to be the case but I'd like to know before I buy something online. It would also be nice to get some official confirmation to add to the 'Alternative Alternators' sticky which is not too helpful as it stands.

 

Thanks again for tutelage so far gents,

 

Lee

 

 

 

[grimlynsan]

Further research on ozdat indicates that you can go get an alt from a VN Commodore, take out the guts, and slide them into the z alt case and you have 85amps.

 

That sounds like a more advance operation though...