1970 Challenger overcharging issue

[brown_devil]

I have an issue with my car overcharging sometimes. Alternator was replaced about 5 years ago and has been working fine until now.

A few weeks ago I was going to a cruise night and while driving on the highway for about 30 minutes the amp gauge pegged to the right and my fuel and temp gauges went to the left (standard dash). I pulled over to check the wiring under the hood and saw nothing wrong. At this point the gauges had returned to normal. I pulled back on the highway and continued to the cruise night since I was only a few minutes away. The problem did not repeat.

I left the cruise early so I would not be driving at night with a possible electrical issue. After about 20 minutes the problem occurred again. Pulled over and the gauges went back to normal. Shut the car off and waited a few minutes and then started the car and continued on my way. After about 15 minutes the gauges again went crazy. Pulled over again for a few minutes, gauges normal so I continued home (about 5 more minutes) with no issue.

Figured I had a bad voltage regulator so I replaced it. Had been using the car only locally around town, no highway driving but had driven for over an hour.

Yesterday I took my car out to go to an event, after driving about 15-20 minutes at around 50 mph, the problem occurred again. Pulled over, waited a few minutes and took the car home with no further problem,

I guess I could have another bad regulator, but I feel there is another issue but don't know where to start. It is odd that it only happens at speed and after a while of driving. Could the alternator or battery be causing this?

Any help would be appreciated.

Thanks,

Michael

 

[Chryco Psycho]

Welcome to the site !
the regulator controls the ground for the field & thus the charging rate .
the regulator is the problem , it has been about 40 years since Chrysler has used this type of reg so most are made in China . I had them fail every year in my truck , Mancini may have a better quality one available so check with them .

 

[brown_devil]

Welcome to the site !
the regulator controls the ground for the field & thus the charging rate .
the regulator is the problem , it has been about 40 years since Chrysler has used this type of reg so most are made in China . I had them fail every year in my truck , Mancini may have a better quality one available so check with them .

The voltage regulator I used was a mopar performance regulator from Mancini racing.

 

[70chall440]

Check the regulator ground, it MUST be clean and well connected. Mopar used sheet metal screws when the cars were new but these wear out and over time they are not providing a solid connection. I replace all of mine with nutserts and use 10-24 screws.

That said, your regulator may have died ground or not, this is not an uncommon occurrence and it doesn't really matter how old or new the reg is. What I have seen is that the ground goes and then the reg burns up.

 

[Chryco Psycho]

I meant to mention a good clean ground is a must ...

 

[brown_devil]

I meant to mention a good clean ground is a must ...

Thanks for all the responses.

I had previously replaced the screw with bolts bolted thru the firewall. I cleaned the paint off the regulator and firewall and used the washers with little teeth on the external perimeter. Testing with a meter I have a good ground connection. I guess it is possible I have two bad regulators. I think I have an old one that I can try.

I thought that if the regulator was bad, it would be overcharging all the time (at least when the RPMs are off idle) but it takes a while before the overcharging occurs and I have to be going over lets say 35 MPH since it has not happened in many rides over the past few weeks. I can't get it to happen just holding a high RPM in my driveway (I only tried for about 5 minutes or so). That is the puzzling part to me. It takes a while to occur and so I was wondering if maybe there could be something wrong with the alternator that happens when it gets hot.

 

[Ele115]

Did your battery swell up or start stinking? It could be in your gauge/s circuit. Take a DMM with you and next time it does it, see how many volts you have at the battery. If you are full fielding, it may be discharging and just pouring it into a discharge too to try to keep up. Verify as to whether or not it is actually overcharging. The equipment between your dash and the battery isn't getting any younger, there could be some things to look at between. You could even have a plate coming loose inside the battery

 

[Cratos]

check you amp meter connections could be shorting out .any electrical add on's electric fuel pump ect have you done the amp gauge bypass?

 

[72RoadRunnerGTX]

Do a visual inspection of the charging circuit bulkhead connections, check for loose ammeter connections. If found to be loose, check for heat damaged ammeter insulators. If you are going to by-pass anything, by-pass the charge circuit bulkhead connections before anything else. All added vehicle loads need to be on the alternator side of the ammeter, nothing should be connected directly to the battery or starter relay.

 

[Cratos]

I disagree, instruction with My by bass wire said go from alternator to battery if you are running through the ammeter, your putting full load from non-factory add on's through it and it will overload it! the purpose of the bypass is to remove the load on the factory harness trust me I know I have aftermarket fuel system and outer stuff, and on the bulkhead connector I had melted the black feed wire. do away with the amp gauge and get a volt meter. when you bypass it.

The bypass kit has a fusible like, so it is also protected

 

[72RoadRunnerGTX]

By-pass kit? By-passing every thing at one shot with a wire running from the alternator output to the battery is nothing more than a band aid, doesn’t address the root causes/problems and defeats the purpose and function of the ammeter altogether. The bulkhead connections in the charge circuit are by far the weakest link in the original design, have been since day one, that is fact. The Packard terminals used were never intended to handle more than a few amps when dry and clean. At a minimum, by-pass these connections with a straight run to the ammeter.

The ammeter is intended to only register charge/discharge current to and from the battery, nothing else. Yes, adding additional loads at the battery on any vehicle running a “battery ammeter” will over-stress the ammeter, and related connections including the alternator lead bulkhead connector, beyond its design limit, as well as falsely register this added current as battery charging current. The ammeter, in good condition, can handle quite a bit of current, loose or poor ammeter connections, failed insulators, cause problems. For those wanting to run high add-on loads and keep the original ammeter function, all loads must be on the alternator side of the ammeter, again nothing connected at the battery. Then for those buying into the “spontaneous combusting ammeter” myth, don't care about the information a fully functional ammeter provides, do the full by-pass.

 

[Cratos]

if you add a volt meter you can see how the charging system is working .these old ammeters are know to short out if you over load it. your still powering the dash stuff through the firewall but high draw stuff like fans ,electric fuel systems high power lighting should be feed from the alt/bat not through the stock fuse box wiring.

 

[i_taz]

Maybe you want to try Chryco's patented 'pack the firewall connectors with die electric grease' trick..?
Fixed my gauges bouncing, headlights and radio dying, not charging at idle but before he suggested that
I did put the headlight by-pass relay kit in which should be standard procedure in any car using the ammeter

 

[72RoadRunnerGTX]

if you add a volt meter you can see how the charging system is working .these old ammeters are know to short out if you over load it. your still powering the dash stuff through the firewall but high draw stuff like fans ,electric fuel systems high power lighting should be feed from the alt/bat not through the stock fuse box wiring.

A voltmeter is as useless as an idiot light for monitoring real time charging system health, much more valuable information available from ammeters if you know what you are looking at. Ammeters with properly maintained connections and insulators are not known for spontaneously “shorting out”, that’s just BS, a myth.

We were dealing with failed bulkhead connections at the dealers back in the seventies, it’s a well-documented weakness in the original design. But then these cars were never built to last more than a few years, until the next trade-in. I read a lot of advice here about replacing full harnesses with new reproductions to address these kinds of issues, “just to be sure”. Problem with that is, they are just expensive reproductions of the original design including the Packard terminals in the bulkhead charging circuit. Guess what, that doesn’t fix anything, they burn up after a short while too just like the originals. Dielectric grease on the terminals is not going to allow corroded or heat damaged Packard terminal handle any more current, not a permanent fix by any means.

Nobody said anything about connecting high current add-on loads to the factory dash harness or fuse block. All factory loads at splice 1 can be feed from the original 12 ga black ammeter lead. Larger gauge runs out to the alternator can have added loads taken off that run. Keeps all load on the alternator side of the ammeter.

 

[moparlee]

A voltmeter is as useless as an idiot light for monitoring real time charging system health, much more valuable information available from ammeters if you know what you are looking at. Ammeters with properly maintained connections and insulators are not known for spontaneously “shorting out”, that’s just BS, a myth.

We were dealing with failed bulkhead connections at the dealers back in the seventies, it’s a well-documented weakness in the original design. But then these cars were never built to last more than a few years, until the next trade-in. I read a lot of advice here about replacing full harnesses with new reproductions to address these kinds of issues, “just to be sure”. Problem with that is, they are just expensive reproductions of the original design including the Packard terminals in the bulkhead charging circuit. Guess what, that doesn’t fix anything, they burn up after a short while too just like the originals. Dielectric grease on the terminals is not going to allow corroded or heat damaged Packard terminal handle any more current, not a permanent fix by any means.

Nobody said anything about connecting high current add-on loads to the factory dash harness or fuse block. All factory loads at splice 1 can be feed from the original 12 ga black ammeter lead. Larger gauge runs out to the alternator can have added loads taken off that run. Keeps all load on the alternator side of the ammeter.

View attachment 85177

View attachment 85178

Looks good, thanks for the pics. What ga red and black wires did you run?

 

[72RoadRunnerGTX]

8 gauge pictured.

 

[i_taz]

I don't think the purpose of the die electric grease is to increase capacity of the circuits.
It simply makes a more secure conductive connection which completely maximizes
it's potential. My radio volume evn went up and down at idle. My knee jerk reaction
was to start looking at power master blaster caster 160 amp alternators and all I would of done
is burned the car up and probably the garage. Now I can turn on lights, heater or radio
and it handles it perfectly. Adding additional loads will change things maybe even
halogen bulbs....IDK. I got a bypass kit for them before I knew the bulkhead trick.

 

[72RoadRunnerGTX]

To be clear, Dielectric grease will not improve or make for a more conductive connection. Dielectric grease is non-conductive in of itself. It’s not recommended it be applied directly to any electrical terminals. For sealed connections, it is intended to enhance sealing on connector/terminal seals designed to seal off terminal connections from exposure the atmosphere. It is to be applied to the seals or boots, to improve the performance of modern weather-proof connections. I certainly would not apply it to old-school under-hood unsealed terminals or connectors, wouldn’t “pack” a bulkhead connector with the stuff. In an unsealed connector the grease can attract dirt and dust, creating more problems.

The Packard terminals used are under current rated for use in the charge circuit at the bulkhead. They have been falling since these cars were new, that’s a fact. Corrosion at these unsealed terminals only accelerates high resistance buildup and resulting heat damage. By-pass these charge circuit bulkhead connections if you want a permanent solution.

 

[moparleo]

Since this only happens after driving for 15-20 lets assume it is heat related. Start your car outside. Turn everything electrical on
( except wipers) to load the system. Set fast idle cam and wait.
You will only find it, if you can test the system when it happens. You have to duplicate the problem to find the fault and then to test to see if it is fixed. Also try the "wiggle test". Yes it is a thing. While running wiggle the connections first on the firewall/engine side. It will be mandatory to use a partner to monitor the gauges.
Electrical can be frustrating.
Die-electric grease( silicone) simply seals the electrical connection from the atmosphere stopping oxidation. Because of its high heat shielding ability it is also used on plug boots to help wire removal during plug servicing.

 

[i_taz]

To be clear, Dielectric grease will not improve or make for a more conductive connection. Dielectric grease is non-conductive in of itself. It’s not recommended it be applied directly to any electrical terminals. For sealed connections, it is intended to enhance sealing on connector/terminal seals designed to seal off terminal connections from exposure the atmosphere. It is to be applied to the seals or boots, to improve the performance of modern weather-proof connections. I certainly would not apply it to old-school under-hood unsealed terminals or connectors, wouldn’t “pack” a bulkhead connector with the stuff. In an unsealed connector the grease can attract dirt and dust, creating more problems.

The Packard terminals used are under current rated for use in the charge circuit at the bulkhead. They have been falling since these cars were new, that’s a fact. Corrosion at these unsealed terminals only accelerates high resistance buildup and resulting heat damage. By-pass these charge circuit bulkhead connections if you want a permanent solution.

I'm in no position to argue and won't recommend it to anyone again but it alleviated my paranoia. Even with all new wiring and bulk head I found an apparent fire behind the one headlight buckets and just recently this little beauty. Don't know how long it's been there but there wasn't one function that didn't sporadically fail at some point until I used the grease. Tach, lights, radio, ammeter all over the place, charging not charging. Now I can turn on the blower and the lights barely flicker..

Before I used it for this, I generally used it as you said, just on plug boats. I'm going to clean
the bulkhead connectors and just put some around the perimeter and see if by tightening that way
I have the same positive results. In my defense, part of my thinking was related to how they encapsulate electronics like the ECU circuity and thought it was used on points ?

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