Dancing Ammeter Continues!!!

[Duffman]

I have gone through and checked any/all grounds I could find and see. All seem to be fine, though I am not sure how to find the end of the ground on the alternator as the wire goes into a harness. What if I ground the alternator directly to the frame, would that help determine anything?

I have checked voltage around the alternator while the ammeter is dancing around, it is consistent but measures from 14.60 to 16.2, and all points in between.

I believe that the problem is heat related, as the ammeter is fine until the engine warms up and then it starts dancing between +15 to -15 while parked. I hear a funny whirring noise that goes up and down, can't pinpoint where it is coming from in the engine compartment. When I turn the lights on (while parked, engine running) the ammeter is straight up, no dancing. Once on the road, it dances wildly and will calm down only a little with lights and fan on, though the lights flicker up and down.

Any thoughts?

[Duffman]

Still battling my problem ... Any other thoughts? Arne mentioned checking the alternator ground, should I run a ground wire from the ground connection on the alternator (with internal VR) to the body and see if that makes any difference?

Anything else?? I can't drive my car and it is pathetic to see a grown man cry ...

Thanks to all for any assistance.

[a7dz]

I am going to ask a couple of questions and then some statements. First question is does the alternator charge the battery? When they did the test on the alternator did they use an amp meter to see if the output was constant or just check the output voltage?

There are two things the alternator needs to charge one is voltage to excite the field and the other is a ground. That being said I am going to go into the things I have done to my car as I am refreshing it. After seeing pictures of your car you may want to as well. I have removed the alternator and bracket from the engine block cleaned both the

Block and the alternator mount bracket and then bolted them back together. I also cleaned the mounting surfaces between the alternator and the bracket. You will notice on your original alternator that there is a capacitor bolted to the alternator case a noise filter. The case of the alternator needs this ground as a reference and also as a second safety path should the alternator short out internally.

The second half of this ground or return path is the starter. It also needs to be clean both at the wires that mount to it and the starter to the block. I did the same here. Cleaned both the bell housing and starter mount points. (Since the motor was out I also cleaned all the mounting points between the block, mounting plate and bell housing.)

The next thing to look at it’s the wiring itself. You have stated that the ends have been cleaned at the starter and alternator. Are the crimped on terminals sound is there any visual damage? The insulation melted, discolored copper showing? Lets go on to the next joint in our cars the red white wire goes to an intermediate connection under the dash some place close to the glove box. It is a male female spade terminal it then goes over to the negative terminal on the amp meter have you check those connections? The white wire does the same under the dash and the goes to a couple of connectors behind the fuse box and then on to the positive terminal of the amp meter. These connections common to the fuse box and behind the glove box have been hot in my car and will be replaced before I put the dash back.

Hope this helps

[Duffman]

Thanks, Jim, I am comfortable about the connections around the starter being clean, secure, etc. I will take the alternator off and clean all contacts, etc. Will also doublecheck the white and white/red wire connections again to see if something is not connected correctly under my dash. Will also check the original capacitor on the original alternator and see how it was wired up. Are you suggesting that I place the capacitor on my upgraded alternator casing? Is there another option to creating a back up ground for the alternator, such as running a ground wire from the frame to the alternator itself?

[a7dz]

Will also doublecheck the white and white/red wire connections again to see if something is not connected correctly under my dash.

If you are charging they are correct you are looking for discolored and or dirty connections. I would take them apart one at a time and rebond them per the instructions listed below.

Are you suggesting that I place the capacitor on my upgraded alternator casing?

No, just that you need a good ground to the block.

Is there another option to creating a back up ground for the alternator, such as running a ground wire from the frame to the alternator itself?

I do not recommend it but, I have run a ground wire from the bolt that holds the motor mount on the block to one of the bolts that hold the front cross member on my car.

The other wire you must take apart and rebond is located just forward of your battery common to the wire harness. The harness terminal connects to the fender well with a Philips screw. It is the main ground wire for most of the systems in your car including the alternator. To rebond it take it apart clean the terminal so there is no discoloring left, then clean the fender well common to nut welded to the fender. I ran a tap through the nut to make sure it was clean. Then I replaced the screw and pressure washer. As you reassemble these connections clean all the surfaces with alcohol being careful not to touch the mating surfaces with your fingers after you clean them.

Finding EMI problems is such fun!!

[Duffman]

Thanks, Jim, I appreciate your patience with an electrical neophyte!!

[Duffman]

Per Jim's instructions, I took the alternator off and cleaned all contact points (wire brushed, etc) and put it back on. I found the main ground in front of the battery Jim mentioned (hidden by wire bundle and black paint!), cleaned the contact points up, put a new bolt and washer on and secured it. I double checked the positive and negative connections on the starter and wire brushed again. I started the car and let it warm up, no bouncing ammeter!!! Took it for a drive and it started to bounce around a little (+10 to -10). When I would come to a stop, the ammeter would read straight up, or slightly to the +. Once I take off, it starts moving around again, though not anywhere near as bad as before. It seems to bounce to a constant "beat"; -10 to +10 to -10 to +35, and repeat. When I turn both the lights and fan on the ammeter reads straight up, just fine.

I feel I am getting close but still something is still causing a problem ...

[DeesZ]

I just read this thread again and in my mind keep coming back to the voltage regulator. My car - 1972 with external regulator (at that time) - had almost identical symptoms, including a strange intermittent sound sometimes under the hood. I cleaned all grounds (twice), checked the wires for soundness, etc.... had the VR & alternator checked, and everything passed with flying colors. Basically I feel like I've been on the same path. Everything I did in the end left me with the same intermittent symptoms of wide and abrupt charge / discharge fluctuations, and sometimes that strange sound. After each attempt at a fix, I imagined it to be a bit better, but honestly, in hindsight it was wishful thinking. Finally, one evening at dusk while out for a ride with the parking lights on, the pimple came to a head and popped. I had just hit a 55 mph stretch with a ricer in front of me, so I contemplated passing (the mad bee sound was annoying me). I noticed the ammeter do it's "charge" thing and didn't think much about it, but then it was the Twilight Zone. I dropped down a gear to dispatch the ricer, and the car sputtered while at the same time every light in the dash (remember they were on) got brighter than any dash light ever should. So, I'm sputtering & glowing now, and smoke is coming out of the dash. There was a pull off on the other side of the road, so I swung across and got stopped. Smoke, dash and console (fuse box) now, and the sputtering stopped when the engine died. Now, after making sure I had no flames, there was absolutely nothing - no lights, no starter, no nothing except a lot of hot wires. I had a friend help me drag her home and pushed her in the garage. The next day I investigated. As suspected, a fried fusible link at the starter - really toast. My friend and I concluded that a new VR was appropriate after installing a new f-link and having the ammeter peg itself on charge right out of the shoot. Got a new one the next day and replaced it. Problem basically solved, except for that intermittent strange sound which sometimes sounded like I had a blower on the old l24 (actually kinda cool, but indicative if an issue). The new external reg was much better than the last, but the intermittent sound, etc, got me off my duff to dig in my pile of parts for an alternator. I had one off of an old 280Z that once lived here, but it had an internal VR. So I did what I was tempted to do and got one of the plugs with diode and got rid of the old external VR when I put in the replacement alternator. Sweet results. For some reason those internally regulated units are superior. Not a problem since. Got a few extra amps from the replacement alternator to boot. So, what I learned here is that all along I had a faulty (intermittently so) external VR, and an alternator that liked to make sounds when it had to really work. Oh, yeah, I was quite lucky, too; the fried link incident burnt out or exploded (yes, in the truest use of the term, "exploded") every light bulb in my car that was on at the time (except one lonely dash light at the speedometer). That explained the Twilight Zone effects. Rod Serling would have been proud. To sum up, the VR and alt checked out fine on the bench, but in use there was a different story to be told. I'd swap in another known-to-be-good alternator and VR to see if your problem will be resolved that way. A worst case scenario is that you still have the problem and that wasn't it. But if it is, there is high potential to loosing your baby to a fire, or at least replacing fried electrical components. Sorry this went so long, but I felt I had to share before another Z gets fried. Please keep us posted.

John

[Duffman]

Thanks, John, that was my next solution; getting a new alternator! I will pick one up tomorrow and see what happens!

[DeesZ]

Great! I hope that resolves your issues. Please let us know. Electronics and their performance can be impacted by the temperature, and they can be intermittent. I'm not very knowledgable in that area, but I have learned that electronic gremlins are some of the worst to hunt down and eliminate. Sometimes the old trial and error method is the only alternative we have available, and since you've eliminated so much so far, I think you are about to crack the case.

[a7dz]

Depending on where you get your alternator Might ask and see if they have a clamp on amp meter and have them look at the output of the alternator. Other wise you are up to changing the alternator. There are three things all common to the alternator that could be causing your problem once we know the grounds and power wires are all correct and clean. A faulty diode, bad or dragging bearing or faulty windings.

[Duffman]

Thanks, Jim.

For me this is a simple solution, as I don't have to search any more for faulty wiring, etc. Now, if this doesn't resolve the issue, I will go back to crying ...