69 Road Runner completely dead , help me diagnose problem.

[1Bad70Charger]

Well why did I know local mechanic putting on the new elec. voltage regulator would not solve my problem.

Car was charging normal for 5 minutes then started overcharging at 16 V+ when i drove a mile and returned him the car!  

Time to go to the guy in the Chicago Metro area who is a Jet Mechanic and has a top reputation for being an electrical guru for old school Mopars.

Taking this better than I normally would but it REALLY SUCKS, especially when I am missing out of the best month of the year in the Midwest (September).

[68neverlate]

It sucks that what you've done so far hasn't resolved the issue.  It looks like it may come down to a shorting issue (as long as the replacement voltage regulator was not also faulty), although a bad alternator might also give you the same results.  You're probably wise to get an electrical expert involved at this point, especially if you're anxious to isolate the problem and get the car back on the road.   

Keep us apprised of progress/info...

[1Bad70Charger]

It sucks that what you've done so far hasn't resolved the issue.  It looks like it may come down to a shorting issue (as long as the replacement voltage regulator was not also faulty), although a bad alternator might also give you the same results.  You're probably wise to get an electrical expert involved at this point, especially if you're anxious to isolate the problem and get the car back on the road.   

Keep us apprised of progress/info...

Thank you my friend and to everyone else, I will let you know what the electrical expert finds as the car hopefully will be in his possession by the end of the week.   

I am also suspecting a short at this point. 

[Bob T]

I had a similar problem in my old 68 Charger, and it cooked the replacement V reg nearly as soon as it went in.
After going as far as I could with it ( and in the middle of replacing some other wiring including wiring to ammeter posts, starter , alt and new electronic dizzy etc ) I took it to an auto electrical shop and they diagnosed that the battery had sulphated up and was running a higher than standard base charge that got way too high when it came off idle. So we replaced the battery and another V Reg - solid state type and it was mint after that.

Yeah, I would'nt be too impressed with your mechanic at the moment either

[flyinlow]

A few other things you might try yourself.
(1) Try an other battery if you have one available , this would eliminate a sulfated battery, or one with a bad cell or have your battery load tested. I would think if it starts a 505 engine that it is OK, but it would be good to eliminate the battery as a problem source.
(2) Make sure the case of the regulator has a good ground to the firewall, with a poor ground they can act erratic. I am not familiar with the electronic replacement regulator for the older system ,but it still would need a clean ground to be able to regulate properly.
(3) Start the engine, run it until the voltage rises to 16 volts. Then pull the field wire off the alternator. Its should stop charging and the voltage should return to battery voltage. ( 12.5-13.0) If it is still charging, you have an alternator problem.

Good luck.

[1Bad70Charger]

A few other things you might try yourself.
(1) Try an other battery if you have one available , this would eliminate a sulfated battery, or one with a bad cell or have your battery load tested. I would think if it starts a 505 engine that it is OK, but it would be good to eliminate the battery as a problem source.
(2) Make sure the case of the regulator has a good ground to the firewall, with a poor ground they can act erratic. I am not familiar with the electronic replacement regulator for the older system ,but it still would need a clean ground to be able to regulate properly.
(3) Start the engine, run it until the voltage rises to 16 volts. Then pull the field wire off the alternator. Its should stop charging and the voltage should return to battery voltage. ( 12.5-13.0) If it is still charging, you have an alternator problem.
Good luck.

Great advice  

[68neverlate]

I went back and reread this thread from the beginning, as well as reviewed a few other references, in order to try and isolate your issue.  I'm not really at the point where I'm convinced this is a shorting issue just yet.  There's a couple of reasons for this.  First, if you had a short, you should have blown a fuse or the fusible link (unless those have been overriden with higher rated fuses than what is called for or a larger wire in place of the fusible link).  Second, even if a short does exist and a fuse/fusible link did not blow, I think the regulator would still limit alternator voltage to 14.5 volts in a correctly operating charging system.  Since you're seeing 16+ volts, it's should have something to do with the voltage regulator.   

The regulator controls the field current/voltage in the alternator rotor.  This current is provided to generate a magnetic field in the rotor which induces a voltage in the surrounding windings of the alternator when the rotor spins.  The more voltage/current to the field, the stronger the magnetic field created in the rotor.  The stronger the magnetic field in the rotor, the more voltage the alternator produces in its windings.  The voltage regulator monitors voltage from the alternator to control the amount of current/voltage it passes to the field in the rotor.  In order to accurately detect the alternator voltage, the regulator must be working correctly and it must have a solid ground. 

Given the above, the first thing I'd check is that the voltage regulator is still good.  If that checks out, I'd then check to ensure that the voltage regulator is properly and adequately grounded when installed.  The ground is made through the mounting screw, the mounting bracket of the regulator and the hole and surrounding area on the firewall that it mounts to.  Scrape off any grime/paint/rust on the firewall to prepare the surface for a good connection.  Ensure that the screw used to attach the regulator to the firewall is clean and cutting into the firewall metal to make a good connection.  Use a larger screw if you need to to ensure that.     

It still could be something else, but give those a look first and see what you find out...

Hope all goes well with mechanic #2... keep us posted. 

[1Bad70Charger]

Thank you my Mopar brother for putting all that energy into studying this thread and coming up with that long informative advice and suggestions.

GReat post thanks again! 

[1Bad70Charger]

Ok, I am hoping I am fixed, after 2nd mechanic (who works as a mechanic on Jet Planes and Mopars on his spare time) had the car for 24 hours, he cleaned up a lot of the wires that i did not need (serving no purspose) that were in my engine bay, he put on some new wires to replace some other wires that he did not approve of, and he hooked up my vacum booster for the big cam, that was previusly on it its own toggle switch, and the vacum booster now goes on with the ignigition (and the toggle switch is now obsolete).  A mechanical fan was also just installed by mechanic #1, and the two electric fans also previously controlled by the same toggle switch, are gone, and so is all that wiring (part of the excess wiring referenced above).

Amazingly, this was enough for at least now to fix my overcharge problem as the car ran 15 miles home, over 25 minutes from speeds from idle, to 2 to 60 mph, without any issues and without any overcharging.
We did put on a new mechancial voltage regulator just to play things safe, but the car was even acting ok with the old mechanical volt. regulator on it.

So, in his own words when I asked him what fixed the overcharge problem he pointed to the all the excess wiring removed in the engine bay, and said one of those wires (and maybe the voltage regultator).

Here is another bizzare thing that happended that he can explain. B/f newest mechanic removed all the excess wiring, my headlights, horn, and gauges would only come on if the key was in the ignition/accesseory mode. After cleaning up the excess wiring serving no purpose in my engine bay the lights, gauges and horn no come on the way they should without a key needed (which I am happy about, b/c its normal now and b/f was not. Any thoughts on any of this guys?    

Time shall see, so far so good, b/f he worked on it the car would start to overcharge within a few minutes while idling, and yesterday I made it home on a 25 minute drive without issue.  Mechanic #2 did not even get into the dash wires to accomplish this, but as you may recall I had mechanic #1 by pass my ammeter to avoid that taking a dump on me.  He also found that the main power lead wire inside the engine bay had a half ass soder job on it, but does not think that would be enough to be causing a short.


I will hope for the best from here and thank everybody for your input!  

[68neverlate]

Glad to hear your back in business 1BAD... now you should be able to get a little more road time in before the weather turns.       

Thanks for posting the info on the fixes... it helps us all learn a little more.  It sounds like the additional wiring installed to run the aftermarket fans and booster might have caused you some grief... but there are quite a few things mechanic #2 did that could have resolved the issue.  It could have been to do with the replacement of the voltage regulator, one of the additional wires may have been improperly wired or had a short to ground (my vote based on what you told us about the lights, horn and gauges)... even the bad solder joint could have been/contributed to the problem.  It would have been nice if mechanic #2 systematically made those changes so he could have told you exactly what resolved the issue, but hey, that would likely have taken him much longer (and cost you more) to fix the problem.  Important thing is that you're back up and running.

Thanks again for the thread...     

[1Bad70Charger]

Thank you my friend.  

I just hope she continues to stay reliable.   As I log in more miles over the fall (great hot rod weather) the more my confidence factor will go up if she continues to operate properly.

Looking to burn some rubber this weekend  as I was down for 3 weeks and have a lot of driving to make up for!   I'm also hoping that I finally found me a very COMPETENT old school Mopar specific mechanic for the future.