eating Voltage regulators

[Sixt8Chrgr]

My car keeps blowing VR's. The one that is on the car is a larger output than should be on there. This is the second one that the car has blown. Like I said the one that is on the car has a higher output rating than what should be on the car. I am going to put a factory output rating on it today and see how long it lasts, but each time it costs me $50. I have put a new wiring harness on under the hood. I have a new alternotor on the car too. Any ideas on what could casuse this? By putting the stock VR on the car I am trying to see if that will make any difference.

Thanks,

L Shaw

[y3chargerrt]

How good are yoru grounds? This includes the engine to body and regulator body ground and negative battery cable.

[Sixt8Chrgr]

How good are yoru grounds? This includes the engine to body and regulator body ground and negative battery cable.

I have checked them and they seem good. I even put a grounding strap from the bottom bolt of the VR to the firewall ground. This big VR on the car now only has one bolt holding it to the firewall due to the size of the VR. When I put the correct size VR on I will use two bolts. But I will also clean all the grounds to make sure.

Thanks,

[Nacho-RT74]

 

[Sixt8Chrgr]

nacho,

I think I must have a voltage spike that is frying the VR. Any ideas on where to look for the spike or an idea of what may be happening?

[y3chargerrt]

Alternator?

[Sixt8Chrgr]

Alternator?

Its new. I know that is no guarantee, but any other ideas?

[moparjohn]

I just had a simular problem, I was also frying the fuse link, I was overtightening the bolt that hold the power lead to the back of the alternator. This would crack the bridge and you could see sparks from there when the engine was running.

[Sixt8Chrgr]

I just had a simular problem, I was also frying the fuse link, I was overtightening the bolt that hold the power lead to the back of the alternator. This would crack the bridge and you could see sparks from there when the engine was running.

Over tightening what bolt? Not following you on this. I have the two bolts that hold the VR to the firewall and the screw for the green wire.  Help me out here.

Thanks,

[resq302]

MoparJohn is talking about the stud on the rear of the alternator that connects the hot lead wire.  If you ground this wire, you get sparks as it is getting a direct ground, aka, short.  This could cause a spike in the charging system which might be blowing out your voltage regulator.  My thought is to remove your alternator and voltage regulator and take them to a place such as Pep Boys or Advanced Autoparts who have equipment that can test your alternator parts and voltage regulator.

[Sixt8Chrgr]

MoparJohn is talking about the stud on the rear of the alternator that connects the hot lead wire.  If you ground this wire, you get sparks as it is getting a direct ground, aka, short.  This could cause a spike in the charging system which might be blowing out your voltage regulator.  My thought is to remove your alternator and voltage regulator and take them to a place such as Pep Boys or Advanced Autoparts who have equipment that can test your alternator parts and voltage regulator.

Ok I got you.

What is weird is that the VR wiill work for a undetermined amount of time then all of a sudden go out. It always seems to go out when I am starting the car. I.e. the gauge reads normal while driving. (I am always scanning the gauges) turn the car off and come back after a while start the car and the amp gauge reads zero or a slight negative charge depending on what accessory is on.

What type of resistence should I be getting between the two leads on the VR. I took one of mine apart and saw a winding and what looked like a set of points. Everything looked fine in there but could have an open somewhere.

Thanks for the help.

Lawrence

[mopar0166]

SImular issue , any updates? 

[Pete in NH]

Hi mopar0166,

Your 69 had a stock voltage regulator that was an electromechanical type. Most  replacements for this type are  now electronic. What do you have on  your car? Also, what type of alternator do you have on the car? The stock alternator has a single field connection, with the other field connection internally grounded. There are a lot of variations coming from re-builders these days and some of them can damage the regulator. Several members here have had issues with these non stock rebuilts.Some auto parts lines now have two classes of parts one a low cost Chinese line that are mostly junk and the better line. Some of the Chinese stuff fails quickly, I think it pays to get the better line in parts like regulators.

[mopar0166]

Yeah i have a 69, with a brand new rebuilt 440 , new trans etc.  switch from a 318/904 setup.    the only stuff that changed electroniclly was installing msd 6al removing ballast resist,  i actually did replace a blue vr for a new electronic one( im questioning the qualtity of this part) and then adding a few more curicuits for fans and f/p.   the alt is a 60 amp i beleive for a 1986 dodge d 100.  it seems to be graounded and putting out power but low at idle.  also when i would drive it above idle id get voltage spikes and it looked like the headlights and dash would flash.  im thinking the grounds maybe need cleaning but also the V/R is trashed.     

ANy thoughts

[Pete in NH]

I'm not sure but, that 86 dodge truck alternator may be a squareback unit. If so it would be an isolated field unit with two field connections. I'm not sure what you may have on your car. A picture of the alternator and regulator would help a lot in identifying what you have on your car so we can pin down what is happening. A voltage regulator for a 69 would not match up with this alternator unless one field connection as grounded.

[mopar0166]

i do have a field grounded and it is a square back

[mopar0166]

alt , grounded

[Hard Charger]

had a similar issue years ago.

my battery would die every week or so depending on how much I used the car.

turned out to be a fried ammeter in the dash. we jumped the alternator directly to the battery and the problem was gone.

I knew the gauge was gone since the needle fell off due to the heat build-up, just never got around to fixing it. tried everything before we figured it out. but I was going thru VR's also.

[mopar0166]

I have already jumped that gauge and don't use the stock gauges any more.   great suggestion though

[Big Sugar]

Had the same issue a few years back, even though the alt tested fine it tunrned out to be a short in the stator and everytime I stepped hard on the gas the load on the belt would short the alt briefly and burn up the battery and if you weren't  paying attention the battery would boil over,  the problem was most likely caused by a over tightened alt belt.

I now run a hassle free Denso Alt with a built in Voltage Reg.......



Ron

[mopar0166]

ill keep that under consideration.  it'd be an easier choice if i havent already purchased a new alt and volt regualtor more then once .   

[Pete in NH]

This issue has come up before on 69's and it gets a bit confusing and complicated. Is the picture you posted actually your car? It seems I've seen that picture in relation to another member who had a similar issue. If you'll note in the picture posted one of the field terminals is not grounded. What is happening on some 69's is that alternator re-builders are adapting later alternators to supposedly fit 69 and earlier cars. They ground one field brush internally but then use a flag terminal that looks just like the other field connection. They don't tell you which one is grounded so you get a 50-50 chance of getting it right when you connect the one green wire from the voltage regulator. If you guess wrong you ground the regulator output and quite possibly damage the regulator. I think it's getting to the point that if you want to run a squareback alternator on an earlier car, it's probably best just to convert over to a full isolated field system with the standard Chrysler electronic regulator.

[resq302]

Like Pete said, the square back alternator is a dual field terminal set up.  In order for it to work with a 69 and older set up, one of the field terminals needs to be directly grounded to the alternator housing.  The other needs to go to the voltage regulator.  Hopefully you did not hook the one wire up to the voltage regulator that was the field that was grounded.  If so, chances are your voltage regulator is toast.

[mopar0166]

That picture was a bit old, i did say it was grounded, and that wire is not connected to the VR.  the issue is what seems to be voltage spikes, i saw the headlights flashing like it was getting jolts of extra power.  it evenrtally blew the head light bulbs

[Pete in NH]

Okay, With one field terminal grounded as it is for a 69, the other end of the alternator field is connected to the output of the regulator which provides a positive voltage. This voltage drives a field current through the field winding and is whatever value the regulator determines is required to produce 13.5 to  14.4 volts or so at the alternator output. The regulator output voltage usually runs somewhere around 8 volts or so. It soundlike for some reason your alternator is going to what is called a full field condition which means the field is seeing battery voltage. This can only happen if the regulator is intermittently going wide open in output or some other type of wiring short circuit or error is intermittently connecting the field wire to the alternator to full battery voltage. My bet would be something in the regulator. It could be some type of intermittent involving a ground connection or some type of break in the printed circuit board if the regulator is and electronic type. I guess it's  also possible some thing is happening internally in the alternator but, I'm not sure I see what the path would be. But, it could happen if the field winding some how got connected internally to the alternator output post. Do you have a voltmeter you can measure the system voltage with when this voltage surge happens. If it eventually blew the headlights it's going to eventually cook the battery as well.