Voltage regulator keeps burning out

[normstow]

Sent: 6/3/2008

My 76 Apollo, (Dodge 440), regularly burns out voltage regulators.  I installed the last one only a couple of weeks ago, and the engine has only been started 2 or 3 times, and it has failed.  I know they fail, as I have fitted a voltage meter, and when the regulator is new, the alternator will push the needle to around 14 volts, (normal).  Then all of a sudden, the needle is pinned to over 16 volts.  A new regulator always corrects this problem, but inevitably, it fails again.  I have replaced it 5 times in less than 12 months.  I have run a new ground from the regulator, thinking this might be the problem, but to no avail.

Has anyone else experienced this problem?

Norm

[MSN Member]

From: DaveVa78Chieftain   
Sent: 6/5/2008
My guess is that you have some faulty wiring.  When you replace the regulator you are moving the wires which results in the problem going away.  I would not be suprised that you could pull the regulator out, then put it (the same one) right back in and the charging system would work ok.  If it does then you have a wiring issue.  The regulator only controls the current going through the the altenator spinning armature.  The armature rotation induces a larger AC current in the field coils.  The diodes in the altenator regulate the AC current back to DC voltage.  If there is a loose or bad connection between the regulator (18 gauge red wire on 3 pin regulator plug) and the battery, then it can think it needs to increase the altenator output.  Several wires (the 18 gauge red sense wire to the regulator and the 12VDC source voltage to the Altenator included) are soldered together inside the wiring harness on the rear of the engine.  That connection can corrode resulting in a bad connection.  When you replace the regulator you end up disturbing the wiring in that area ergo you think you just fixed the problem.  Vibration and heat expansion cause the problem to return.  The problem could also be a failing fusable link at the starter solenoid (mounted to the drivers side frame rail).  Because it is a smaller gauge wire than the rest of the circuit, they can overheat and weaken with time.  Could be broken down do to overheating.  This is a case of working through the charging circuit until you find the faulty connection.

Dave

[normstow]

Sent: 6/6/2008

Thanks for your thoughts Dave.  I will play around with the wiring on the weekend, and see what happens.  If I can't find anything wrong, I am taking it in to the shop next week, and I'll let you know what they find.  Thanks again for you input.

Norm

[denisondc]

Sent: 6/6/2008

A few years back, when I had the radiator out of my Winnie and had removed the intake manifold off, I ran new wires from the alternator, to the vr and to the connection to the main wiring harness. The old wire I removed looked pretty ratty, and was somewhat brittle as wel

[MSN Member]

From: olhillbilly31   
Sent: 6/7/2008

i noticed on my Southwind during the recent problems i was having, that my wires from the alternator looked to be in  bad shape to.. like at one point somebody had hooked into the wires with something, then removed it and left bare spots.. so i got to rewire that...

but how hard will it be to do some major rewiring under the doghouse and dash, is this somethign i should attempt or get somebody to do it..

billy

[MSN Member]

From: island_winnie   
Sent: 6/22/2008

Been dealing with the same thing. I was on VR #3 and looked at voltage levels. The charging voltage was way too high at 16 and better. It dropped to 14 or so after about 30 minutes. This generally indicates a bad ground, so I cleaned everything up, installed toothed washers, and no change. Played some more and brought a good ground directly to the case of the regulator. Bingo - all fine. I've since moved the regulator off that rusty old steel plate and installed it on the dog house frame. Looks like better cooling there. Also look at the ground from the transmission to the frame. It's usually a #10 wire. Make sure the connections are clean and solid.
If the voltage is high, you are right to look to grounding. Now I'm not worried about my batteries going poof after one year.
Jim.

[normstow]

Sent: 8/6/2008

Well, for those interested, my overcharging problem turned out to be the alternator.  After checking all wiring, grounding, and multiple regulators, I insisted the shop change out the alternator.  Bingo!!  Just did a 300 mile round trip over the cascade mountains in very hot weather, and the Apollo ran flawlessly, and the charging voltage never moved from around 14 volts.  Even on a test bench the alternator checked out ok, so must have been intermittent.

[Phåråoh]

Sent: 8/6/2008

Thanks for giving us the verdict!  It's always of greatest benefit when members post the results of their troubleshooting efforts.

~ Phåråoh ~

[DaveVA78Chieftain]

Sent: 8/7/2008

Components expand with heat.  Most likely a diode or some wiring either shorted or opened when the Alternator heated up from usage and the engine heat.  That would be intermittant (ok cold, fails when hot).

Dave

[DanielTBolger]

Usually, that happens when its charging a lot of batteries  I found out they make a 125 amp alternator which will work with a big block Chevy.  I've also put this alt. on some Dodge tow trucks with 440s in them.