stock alternator burns brushes

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W-Edge

W-Edge

raceheads.ca
Joined
Mar 8, 2017
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Location
pointe des cascades , quebec
When I say burn I mean burn like on fire inside! Got the car in december , did lots of work to it , now finally driving it but everytime I head out it burns the field brush(the one closest to the valve cover or that angles down to the center hub on the shaft). At first I realised it just stopped charging , came here found info did all the tests that were suggested everything checked out good except field connections at alt., after removing and opening alternator to see why I found the brush melted into the plastic housing , got it unstuck , put it back together and worked great , got new brush kit from auto parts (standard cx-1t) and replaced it (even though it worked ok at this point) got my tags , headed to our cruise night passed on the highway(got 4.10 gears)saw close to 6000rpm , got there parked had funny plastic smell , started it up , not charging , headed to a friends place close by (he has a batt. charger) put the batt on charge got the brush out managed to get it unstuck , left impressed my friends with a nice sideways start dont know if mopar chrome box has a cutoff but it felt like it bounced against it a few times 1st and 2nd gear power sliding sideways , when it straightened out I lookesd at amp gauge and got the needle on lowest position(first time it goes that low) , funny plastic smell again , pulled over only to see fire inside alt and carbon on brush core was glowing red , blew on it to put it out but plastic would reignite untill carbon cooled down then I limped it home on battery power! Question is what to do , anyone make a ceramic holder for the brushes , any other material than carbon for the core itself? pulley change , seem to only find ford and chevy pulleys , combine those two solutions??? What about a gm alternator anyone ever try to fit their guts in the mopar housing(I like to keep a stock look)??? Will upload pics later...
 
Sounds like the brush is not seated properly on the Comutator Rotating element. You could have high bars on it. Is brush yellow and bluish on end.
 
Just guessing, the field winding might have a shorted turn. The short cannot be detected with Ohm meter since since one shorted turn of about 100 turns is too small to detect. The typical operating current falls in the range of 3 to 5A, beyond that is a problem. The brush issue suggests too much current, that suggests the short, because it will result in high current.
 
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loganscuda said:
Sounds like the brush is not seated properly on the Comutator Rotating element. You could have high bars on it. Is brush yellow and bluish on end.
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That is good info i m waiting on a new set of brushes will check the contact , is it possible that it needs to wear in to the round contour before I can rev it? And no it is just a chalky black (carbon) it does have a polished look where it contacts the hub or reluctor (donno how to call it really). When you ask if it is yellow do you mean like a bronze brush , because that is what I m used to in brushes , wouldn t mind changing materials if anyone knows where to order them!
 
KitCarlson said:
Just guessing, the field winding might have a shorted turn. The short cannot be detected with Ohm meter since since one shorted turn of of about 100 turns is too small to detect. The typical operating current falls in the range of 3 to 5A, beyond that is a problem. The brush issue suggests too much current, that suggests the short, because it will result in high current.
Click to expand...
How do I test that , do you suggest repacing the alternator all together??? Thanks for the replys , keep em coming...
 
Yellowish is a sign of arcing the brush should have even wear all the way across the end look for scoring. Hopefully you don't have 50 year old wiring as a new alternator will be higher amp. May cause more issues. Don't quote me in that. But if your wiring is old I would replace. Car fires suck. Carbon is the best brush material. Your brush holders may be worn out
 
There's a procedure right in the shop manual for testing field current draw. I've posted this a skidzillion times. Go to MyMopar and download free service manuals and aftermarket wiring diagrams. You're welcome

I agree......screwed up commutator surface, or short in field windings
 
Problem solved got a rebuilt alternator 60 amp from parts store and so far so good , just charging a little high (15.9v and sometimes meter goes bit over 16v) , I am concerned about that , have retested all wires don t know if I should try a regulator , when I test the voltage at the alt output the reading fluctuates a bit but every 10 seconds or so it drops to like 6.xx volts and then back up again for another 10 secs.??? should I try a regulator or is the new(rebuilt)alt. screwed up...
 
This overcharging (over voltage) IS ALMOST ALWAYS due to either voltage drop in the harness or ground path voltage drop between regulator and battery. I've posted on this hundreds of times

In rare cases this is caused by the regulator, and also rare is a battery going bad

To test for harness/ ground voltage drop:

1....Turn the key to "run" with engine stopped. Hook your voltmeter as close as you can get to the bulkhead feedthrough the "ignition run." This connect to, amoung other things, the VR blue, the alternator blue, and the key side of the ballast resistor

hook your other probe to the POS battery post. You are hoping for a very low voltage, the lower the better. More than about .3V (3/10 of one volt) means you need to start looking

The functional path for the VR blue wire voltage is Battery........starter relay stud.........fuse link.......bulkhead connector.......ammeter (RED)........through the ammeter........out on BLACK........to the welded splice........branch off to IGNITION SWITCH connector.........through the switch.........back out the switch connector on blue "ignition run"......out the bulkhead through the firewall...........and to the under hood ignition loads.

ANY OF THOSE POINTS can and will cause drop

2...GROUND...........run this test with engine running at "low cruise" first with all loads off and again with lights, heater, etc running

Stab one probe directly into the mounting flange of the voltage regulator..........Stab the other into the battery NEG. Again you are looking for a very low voltage, zero is perfect, the lower the better.
 
67Dart273 said:
This overcharging (over voltage) IS ALMOST ALWAYS due to either voltage drop in the harness or ground path voltage drop between regulator and battery. I've posted on this hundreds of times

In rare cases this is caused by the regulator, and also rare is a battery going bad

To test for harness/ ground voltage drop:

1....Turn the key to "run" with engine stopped. Hook your voltmeter as close as you can get to the bulkhead feedthrough the "ignition run." This connect to, amoung other things, the VR blue, the alternator blue, and the key side of the ballast resistor

hook your other probe to the POS battery post. You are hoping for a very low voltage, the lower the better. More than about .3V (3/10 of one volt) means you need to start looking

The functional path for the VR blue wire voltage is Battery........starter relay stud.........fuse link.......bulkhead connector.......ammeter (RED)........through the ammeter........out on BLACK........to the welded splice........branch off to IGNITION SWITCH connector.........through the switch.........back out the switch connector on blue "ignition run"......out the bulkhead through the firewall...........and to the under hood ignition loads.

ANY OF THOSE POINTS can and will cause drop

2...GROUND...........run this test with engine running at "low cruise" first with all loads off and again with lights, heater, etc running

Stab one probe directly into the mounting flange of the voltage regulator..........Stab the other into the battery NEG. Again you are looking for a very low voltage, zero is perfect, the lower the better.
Click to expand...
ran the first test and got 2.8v with the field wire disconected at alt , if I connect it I get full battery voltage(exact same reading) , didnt do the second test (got to open door=ten thousand musquitos)but have tested ground at engine alt and regulator also ran awire direct from VR housing to batt. Without any change , charging was fine before the brushes caught fire then got new alt and overcharging , tried old alt today with new brush and it caught fire right on startup(used to require a trek in the 6 to 7 k to melt brush)so that test was useless , I also put the rotor from the new alt in the old(short was in the field winding)and no change(whereas it use to charge perfect before the fire)...Oh yeah I get serious arching when I unplug the blue field wire at the alt.
 
You may have burned some wires and have an in harness cross connect between wires. If you get the battery charged up, and wind the engine up to simulate highway cruise, what does the voltage run?
 
It might be the regulator may be bad. The overcurrent with bad rotor may have shorted regulator field transistor. That will give the the alternator full field, and result in over voltage. It is not good practice to pull field connection while running, that can damage regulator, or shock enough to stop a heart.
 
67Dart273 said:
You may have burned some wires and have an in harness cross connect between wires. If you get the battery charged up, and wind the engine up to simulate highway cruise, what does the voltage run?
Click to expand...
As far as the wires I checked the best I can , unplugged it at field conn, at ball resistor at firewall (in and out , 2 wires) and back to starter relay , since i ve had the car the horn relay didn t work replaced it , the resistor died too and also the starter relay , so those are all new , i ve had the dash out completely to clean up all the wires (had a problem with dome light and hazard circuit) , on the same token I cleaned and tightened all connections to the cluster fuse box etc... Just to say I didnt recheck at amp gauge. I check resitance and it is all @ 0 and no continuity to ground. One thing I can mention is when I was working with the dash off if I didn t connect the amp gauge wires together the car was dead , no start no lights no fan no radio nutinn DEAD! Is this normal or am I missing a circuit somewhere? I m sorry if I am thickening up the plot here but I think more info is better.
 
KitCarlson said:
It might be the regulator may be bad. The overcurrent with bad rotor may have shorted regulator field transistor. That will give the the alternator full field, and result in over voltage. It is not good practice to pull field connection while running, that can damage regulator, or shock enough to stop a heart.
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Good advice , and for the regulator it is what I think , I checked on dealerconnect yesterday ran the part # and ther is one in stock in montreal warehouse wich means I will have it monday at 12.30pm dealer net is 23.10$cad. employee price is cost +10 , so like 30 bucks tx in. I will try it @ that price but I m still going to try and find if there is an underlying issue!Thanks guys...
 
Oh yeah , tested battery the old way(toaster) holds 800amp for over 20 secs. Electronic tester doesn t detect any flaws (dead cells , reverse polarity...). Also batt will run without alternator for about an hour and still start(weak but itll start), this batt came with the car has a 2015 date on it and I must say one of the best batteries I ve ever had(duralast gold gr24 750cca, don t work for them never even seen that brand in canada(car bought in U.S.)just like to say it when someone has a good product).
 
I had one do that. It went to 20v.
Bear in mind that running wide open with zero regulation,(that's full-fielded) that alternator can practically be used to weld with. I have seen 60 Vac come out of one. So, if the regulator cannot tame the beast to 15ish, thru the ground circuit, then it's defective.
I replaced mine with one from the junkpile and away we went.Oh yeah that's a funny story by itself. I had about a half dozen spares.And they were all regulating at different voltages; from about hi 13s to hi 15s. I picked one that hit 15.2 and called it good; that was a good 10 years ago. My alt is a cobbled together item with each major player from a different alt.( I had a box of maybe 15 of them). Over the years I have replaced each player (coil,rotor and diode pack) at different times at least once. And the brushes several times; once even with new ones,lol. I tell you tho, replacing individual diodes was my least favorite operation. But I figured it was good for my education. After that, I just reconditioned a couple of alternators for spares.I carry spare brushes in my spare parts kit, with a ballast resistor and bulbs, fuses, etc.
 
67Dart273 said:
You may have burned some wires and have an in harness cross connect between wires. If you get the battery charged up, and wind the engine up to simulate highway cruise, what does the voltage run?
Click to expand...
The voltage will quickly go from batt V at strtup to 13.8/14v and even at idle will creep up to 15.5+and if you rev it off idle 1300/1500rpms then it will keep creeping up to 17/18V...Amp gauge reads high(normally 9/16 what it used to read, now 11/16to3/4 @ idle and a feather on the throttle will twist the needle at the end).Ran a jumper from alt. output connection to batt pos+ and amp gauge read normal...
 
The jumper bypasses most of the charge current to the battery, and so it would be normal to see the amp gauge read normal. But if you put a volt gauge across the battery, you will still see the voltage climbing. The amp gauge just shows in what direction the electrons are flowing, and what the difference in potential is between the two sides. If 16v is coming from the alt, but you are also sucking 16 out on the "run" side then the gauge will read normal. If 12.5 is coming from the alt, but the "run" side wants 16v, then it will read discharge. So it's showing direction and difference. In your case there might be 17 coming from the alt, but the ignition might be drawing only 7 or 8, so then you see the huge potential difference. It is the regulators job to keep the potential more or less equal on both sides of the ammeter.
But anything significantly over 15 will eventually damage the battery, and possibly some of the more voltage sensitive devices. Also the dash-gauge regulator will drive the temp and fuel gauges up to a higher level.
The regulator is responsible to regulate the alternators output to a manageable level. After start-up, the battery has been depleted of some power, and it is normal to see the voltage come up for a minute or 5 even at colder temps. But as the battery gets refilled, the charge voltage should return to normal; about 13.5 to 14.2 on these older cars. GM has run 15.2 for decades, and we Mopar guys use the same batteries, so when I found a regulator in my stash that held 15.2, I just bolted it in; it makes for nice bright headlights.
So, if you are getting over 16 the reg ain't working right, get rid of it. The amp gauge is verifying that.
 
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does your regulator have a good ground path (its the case mount to the fender) I would sand contact point and use star washers between regulator and fender. Are you using a squareback or round altrernator? squares usually use electronic regulators, rounds were mechanical. I think last 1 year the round had the dual field of the squareback.
 
W-Edge said:
The voltage will quickly go from batt V at strtup to 13.8/14v and even at idle will creep up to 15.5+and if you rev it off idle 1300/1500rpms then it will keep creeping up to 17/18V...Amp gauge reads high(normally 9/16 what it used to read, now 11/16to3/4 @ idle and a feather on the throttle will twist the needle at the end).Ran a jumper from alt. output connection to batt pos+ and amp gauge read normal...
Click to expand...
Voltage climbing like that indicates wiring or regulator problem. Part swapping, may lead to damage of new parts. Best to use a meter, check field wiring. One goes to 12V IGN, often blue wire, the green goes to regulator field terminal. If the green wire is shorted to ground, the possibility that 67Dart273 suggested, then that would result in full field problem. With green wire disconnected at each end an Ohm meter test to ground could be used to test for short, it should read open.
 
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pishta said:
does your regulator have a good ground path (its the case mount to the fender) I would sand contact point and use star washers between regulator and fender. Are you using a squareback or round altrernator? squares usually use electronic regulators, rounds were mechanical. I think last 1 year the round had the dual field of the squareback.
Click to expand...
squareback and ran wires directly from VR body to batt ground(-)and also @ alt. , with no change.
 
KitCarlson said:
Voltage climbing like that indicates wiring or regulator problem. Part swapping, may lead to damage of new parts. Best to use a meter, check field wiring. One goes to 12V IGN, often blue wire, the green goes to regulator field terminal. If the green wire is shorted to ground, the possibility that 67Dart273, then that would result in full field problem. With green wire disconnected at each end an Ohm meter test to ground could be used to test for short, it should read open.
Click to expand...
Tested wires , no short to ground , will try regulator tonight , available from mopar , already ordered it should get it at 12.30pm , will post tomorow if it fixed problem . Pretty sure when original problem with field winding(short)caused fire in the brushes(amp gauge went totally dead)some current peak destroyed the regulator!
 
Does anybody know where and how the regulator should be mounted , I think it is correct on the car next to the master cylinder but should it be mounted with the plug up top or down?I see lots of people mount it plug down , I m asking because I assume some people will mount it like that because of the writing on it!Mine is chrome (no writing)and plug up...
 
FWI
I recently had the pleasure of working on a 77 Dodge Sportsman van.
The vehicle ran perfect except when I pulled the lights on.Charge voltage was good. I felt the voltage to the coil was a little low. I cleaned everything in sight, charged the battery. Took her for a spin. Everything was good. Pulled the light switch and all the world was smiling. Turned the heater blower on and as soon as I came to a stop, the engine stalled. I full-fielded the alt(which was new) and it was putting out plenty. Charge voltage was right on.

Well I got to thinking. And at my age that sometimes runs into days. You might not believe this, but when I get a problem like this where everything checks out, but there is an obvious problem,and I get stumped, well I just walk away. I present the problem to my brain and let it work on it like it was a separate entity. Sure enough a couple of days later, while I'm doing something completely unrelated, the answer comes to me. Man, I don't know how that works but I love it!
The thought comes to me that the ammeter is defective. And it was. The shunt was not passing enough current on the run side thru what was left of it. So I fabricated a new shunt way bigger than it needed to be, and strapped it across the posts . And voila all is right in the world again.
Except of course the ammeter doesn't work,anymore.
No problem says the customer, I'll find you a replacement some day.
So moral of the story; just cuz the ammeter looks like it works, might not in fact mean; that it is working correctly.
 
AJ/FormS said:
FWI
I recently had the pleasure of working on a 77 Dodge Sportsman van.
The vehicle ran perfect except when I pulled the lights on.Charge voltage was good. I felt the voltage to the coil was a little low. I cleaned everything in sight, charged the battery. Took her for a spin. Everything was good. Pulled the light switch and all the world was smiling. Turned the heater blower on and as soon as I came to a stop, the engine stalled. I full-fielded the alt(which was new) and it was putting out plenty. Charge voltage was right on.

Well I got to thinking. And at my age that sometimes runs into days. You might not believe this, but when I get a problem like this where everything checks out, but there is an obvious problem,and I get stumped, well I just walk away. I present the problem to my brain and let it work on it like it was a separate entity. Sure enough a couple of days later, while I'm doing something completely unrelated, the answer comes to me. Man, I don't know how that works but I love it!
The thought comes to me that the ammeter is defective. And it was. The shunt was not passing enough current on the run side thru what was left of it. So I fabricated a new shunt way bigger than it needed to be, and strapped it across the posts . And voila all is right in the world again.
Except of course the ammeter doesn't work,anymore.
No problem says the customer, I'll find you a replacement some day.
So moral of the story; just cuz the ammeter looks like it works, might not in fact mean; that it is working correctly.
Click to expand...
Wow! Me too , I leave it alone and it just dawns on me , but in your reply you made me remember the day the alt caught fire about 45 mins before , I was sitting at a traffic light when for no reason I turned on the heater blower and the car just stalled , fired right back up ! What is this schunt thing , where do you get that?


Thanks to all so far , lot of helpful trails and tests I don t understand...And no , new regulator didn t fix anything .
 
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