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Alternator problem

B

BigDanT

Member

I've got an issue with a 8n sidemount I just got back together. Put a new remanufactured alternator on it and noticed it was putting out just under 16 volts. Took that off , went to Autozone and had it tested, it failed and was given a different one. I installed it and started the tractor, had the same results. I understand I could have gotten another bad one but, we tested this one before leaving the store and it tested good. The alternators are Delco 7127's and are wired like many I have done before, #2 terminal jumped to B post, 12 gauge wire running form B post to terminal block on dash, #1 spade terminal running to coil side of terminal block with a diode installed inline. I'm using all new wire and have a volt meter installed instead of amp meter. I made sure the in dash volt meter was correct by using my Fluke meter while running and it showed the same, just under 16 volts. I also checked the voltage at the #2 and B post terminal while not running and had the correct battery voltage. For giggles I removed the #2 jumper wire and started the tractor, tester showed 14.3 volts at the battery while running??? Could this be a one wire alternator? They tested them at the store with 3 wire connectors and I have used this type before as 3 wires with no issues. I'll be the first to admit I'm electrically challenged but this seems like it may be something simple I'm just overlooking. Any help would be appreciated.

Dan
 
Just for fun run your #2 wire back to battery + at the battery and see what happens.
# 2 is voltage sense and can not get the best reading for voltage needs at Batt + on the Alternator.
 
This explains remote sense a bit

http://www.delcoremy.com/Alternators/Alternator-Features/Remote-Sense
 
If it is trhe common Delco 10si you have 3 wires. The charge wire which goes to the amp gauge. Then you have the 2 wire plug. The #1 wire has the diode in it and goes to the coil ignition side or the switch and the #2 wire goes to the charge stud on the alternator so it knows when the battery has a full charge
 
Old...no amp gauge, has volt meter. System is pretty much wired as per your description except charge wire is going to hot side of terminal block on dash instead of to amp meter.
 
Same difference then ya most would say same thing but not me I like to do things in odd ways some times same as I say down side up instead of up side down
 
I've had three cheap autozone rebuilds go bad, one after the other, after a short time running. They tested fine at the store before I took them home.

When they rebuild these things in the factory, they only replace the bad components, and only test them long enough to confirm basic functionality. If they ran them for any length of time under load, they'd never make it out of the factory.
 
Someone correct me if Im wrong, but you have it wired for an AMP guage, not a voltmeter. The charge wire should go straight to the battery, and one side of voltmeter to battery, the other to ground??
 
Charge wire goes to the amp gauge the non load side so as to see the amps be they + or -. If it is wired right to the battery the amp gauge will never show anything
 
Something else you should check.

Check battery voltage to see what you battery reads not running. You may well have a volt gauge or if your using a VOM you may have one that is not calibrated so. If say you read 12.3-12.6 not running then you are right in the ball park for a correct reading but if your reading say 13-13.6 volts not running then your VOH is out of calibration so any volt reading you take will be off by how ever out it is
 
John M...If you wire your volt meter that way your volt meter would show the battery voltage all the time. I ran the positive side wire from volt meter to the key switched side of terminal block and the negative side of volt meter to ground. Volt meter only shows voltage when key is turned on.
 
Old... I tried that, battery voltage is right on at 12.5 not running. I also checked spade terminal #2 and the "B" post on back while not running and they showed correct voltage of 12.5. I'm still stuck on why the alternator would put out the correct charge voltage of 14.3 when I disconnect the #2 spade form the circuit. Oh and I tried running a wire direct from #2 to the battery but that made no difference.
 
15.2 volts is high side of General Motors "acceptable" limit range. Sounds like all is well to me.
 
Sounds like you need to take it back to auto clone and go to a real auto parts store and buy one. I get all mine form O'Reilly's auto parts and cost is around $45 plus a core and they have a life time warranty to boot. I by ones made for a 1980 Chev pick up no power any thing no AC
 
JMOR..help me out here, if 15.2 volts is GM's high side of the acceptable limit and I'm getting 16 volts how can that be classified as "all is well". Keep in mind that the 16 volt output is at dead idle, I have no idea what would happen if I went to full throttle.
 
Yep, I get all my air fresheners at AutoZone, and all my AUTO PARTS at O'Reilly's. Give you an example, put on my wife's Honda a Auto-Zone Honda steering pump, drove extremely stiff until it completely locked up going 70 mph on I-35 around Kansas City. Never again.
 
not trying to argue but 12 volt coil has internal resister to cut to 6 volts . If your wire is hooked to batt side of coil ok if hooked to side going to points then is six volts. Pleas im not trying to be a know it all just had years of doing it the hard way LOL
 
Wilson...maybe this will help clarify. I'm wired up just like this except I've jump #2 terminal to Batt post on alternator, shouldn't matter they would both end up in the same place.
a246717.jpg
 
Hello BigDanT,

Make sure your alternator is grounded. Battery negative post to alternator housing should be close to zero ohms,

Gujdo.
 
True 12 volt coils DO NOT have an internal resister period!!!!!!!!!!! They are wound in a different way so that internal resistance is such that they work on 12 volts like a 6 volt coil work on 12 volts with a ballast resister. So there in no internal resister in them.

As for the coil effecting the out put of the alternator again nope to different circuits that work with out each other and do not effect each other.

Just like having lights on a tractor they do not effect the ignition system or the charging system because that is another completely different circuit that work independent from each of the other 2
 
This sounds like you have gotten a couple of bad alternators.

I can see nothing wrong with your wiring.

I have never tried disconnecting the #2 wire, but I would think that would increase the voltage, not lower it.

There is a D shaped hole on the back of the alternator where you test the regulator by grounding the tab inside to the case.

Something you might try, with it running, carefully insert the volt meter probe into the D shaped hole in the back of the alternator without touching the case. If you do not get a reading, or the tab shows continuity to ground, the field is shorted to ground, the regulator is improperly installed, or the regulator is shorted internally to ground.

It would not be uncommon for several alternators to have been assembled wrong or have defective regulators. Even though they said they tested it, the test is only as good as the "technician" reading the test.

Do you have another vehicle with the same alternator you could try?
 
Had a neighbor that wired number 2 wire between resister and coil. That's where I though had you done that you would be getting lower signal to alternator. I can see that is not the problem as to your schematic .
 
No it would be called a 12 volt coil plan and simple. Yes the internal resistance is made to work on 12 volts but that is not an internal resister. Works the same as light bulbs. I.E. hook a 6 volt bulb to 12 volts and it burns out but hook a 12 volt bulb to 12 volts and it works. Why well because the internal resistance of the filament of the bulb handles 12 volts and it does not have an internal resister in it
 
Try moving the #2 wire to the charge stud on the alternator that way you do not have a long piece of wire to add resistance and you also only then have 3 inches of wire so less likely to ever break or get hung on something or other wise go bad
 
(quoted from post at 10:12:42 12/30/16) Same difference then ya most would say same thing but not me I like to do things in odd ways some times same as I say down side up instead of up side down
Click to expand...

And there you have it folks, straight from the horses mouth! :lol:
 
I'm with the other guys, take that alternator to an auto electric shop and have them test it.

When the MN based company "Gopher Motors" was still in business the standard joke with mechanics was "put one in a go fer another". And yea they were that bad.

And another poster stated the facts. Some auto parts chains, so they can sell at cheaper prices, have them inspected and repaired as needed only. The places that do that kind of work generally used the cheapest source for replacement parts and hire the cheapest employees too.

Old an me don't get along sometimes to well but in this case he dead on!

Rick
 
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