For ignition issues, ALWAYS CHECK THE ALTERNATOR TOO!

Gerald Morris

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Despite sometimes insufferable pride in being an “original thinker” when new to a given discipline, I follow the prescriptive thinking of that discipline’s cognoscenti scrupulously and often to a fault. This being only my second C body Mopar, with the first barely serving me for 3 months before illness, physical and fiscal collapse all converged to remove it from my grasp; I have consulted those sources of prescribed diagnostic method, mechanical technique, material sources et al with the solid satisfaction of seeing every procedure succeed with expected results, until this particular issue arose last night and came nigh to rendering my 66 Newport 2 door hardtop so much rolling scrap iron. Had I not been blessed, (Deo gratias!) with the foresight to install a knife-switch as a kill switch on the negative post of the battery, then all my advanced coursework in electrical engineering, physics combined with years of practical experience with machinery and wiring installations would NOT have availed me toward saving “Mathilda” from the sorry fate of a completely incinerated engine compartment and console wiring harness. Likewise, had I not done exactly the right thing without wasting any time, then all that foresight simply would have become yet more poison salt in the cup of woe I would have had to drain to the last drop.

For the past month, Mathilda showed symptoms indicating a failing ignition coil with ballast resistor and condenser as the other elements in the classic RLC “tank circuit” which I retain for simplicity’s sake as the ignition system. I had already replaced the breaker points first with execrable Chinese garbage from Oh Really? Auto Parts, then excellent NOS Mopar points which served perfectly for the first 3 weeks of April. Then, a slight stutter began to appear in the ignition requiring me to feather the gas pedal a little on take-off or for substantive acceleration in motion. I surmised that I should have included an ignition coil with the rest of my replacements/tune-up and wound up ordering a good Standard from Rock Auto with a second condenser also by Standard to match. Thus, I hoped that inductance and capacitance would be optimally paired and the stuttering ignition would cease for good. I also changed ballast resistors though both of mine read between 0.500-0.700 Ohms, as specified and neither is too badly oxidized, yet….

With only 3 exceptions, my expectations of the new ignition circuit have been happily fulfilled over the past 11 days. Despite the extreme wear on the OLD 383, Mathilda showed the expected bounce in her step. I even tightened a puzzlingly loose battery terminal on my old roundback 60 amp alternator, with apparent good result. But Mathilda still stuttered on 3 occasions the past 10 days…. ALAS! THE 3 EXCEPTIONS PORTENDED AN UGLY REALITY!

Despite having Mathilda VERY NICELY tuned, with even a decent dwell of ~ 28 degrees and a “bump start” requiring just a slight squirt of petrol into the Stromberg after reducing the idle down to ~ 550 rpm, I STILL HAD THOSE SEVERAL SLIGHT IGNITION STUTTERS! I really had resigned myself to a complacent notion that, “Well, its very old and perhaps some ‘slight wiring problem’ has evaded my attentions.” OH HOW SMUG! Pride led me to this precipice.

I planned to replace all my swaybar and strut bushings for today, as warm-up to the ball joints and connecting rod ends. The Monroe OE Spectrum shocks did a LOT for the front end after upgrading from 25+ yr old NAPA shop shocks. I had to adjust the front brakes after installing a new drum and set of pads. Really, I have PLENTY TO DO to this nice old functioning relic. Evidence abounds that I bought something hastily assembled after sitting for years in an old man’s garage, by a none too apt heir who wanted nothing more than what little money he could get for it. I can’t and don’t complain about price. I KNEW what I was getting into. So the following didn’t surprise me at all, really.

Last night, after fueling just a short block from home, I pulled into traffic and THE STUTTER BECAME A DEADLY SEIZURE! FAR worse than ever before, the engine misfired and ALMOST died, then the ACRID SMOKE of 50 yr old thermoplastic insulation began to pour out of my dash and from under the hood. The lights dimmed to dark orange. I hit the ignition key and coasted off the street into the front parking lot of the trailer park across the street from my own. I stopped, hit Park, jumped out keys in hand and unlocked my hood, which I normally keep locked with Master padlocks in clip pins up front. I raised the hood, saw RED GLOWING WIRE THROUGH THE SMOKE, and opened my kill switch. From the first stutter to my opening the kill switch not more than 40 seconds elapsed. I know, I saw this on the smart phone I use for a GPS speedometer.

After the smoke cleared, I saw that not a speck of thermoplastic remained on any wire attached directly to the battery + terminal or the alternator charging terminal. I realized that one synapse of suspicion I had regarding the alternator was the RIGHT one, DAMNIT! I got out my flashlight and started cutting bare, burnt clean stranded copper wire from any connection to anything that would give it current. Then I jumpered the ignition coil, used a flat screwdriver to bump the starter from the ONE wire which DID NOT BURN, the main one from the battery to the starter relay up top of the firewall, and my good tune-up got Mathilda and I around the corner to home, sans any lighting. I showed the wife the strands of insulation-free stranded copper, and she SMELLED how much thermoplastic oxide had deposited itself onto my skin.

At the crack of dawn, I started pulling and cutting apart the ruins of the old ignition harness. Having told the wife that I now strongly suspected the alternator, but still had to consider the prospect that the jury-rigged (to be polite) home crimping job I found on ONE key strand going through the bulkhead connector MIGHT have caused last night’s calamity. I profusely thanked Jesus and St. Joseph for inspiring me to install that kill switch, as had it not been there, so much as another MINUTE really WOULD have been enough to ruin ALL the wires from the battery to the ignition switch. I then pulled the remains of the lug off the alternator, AND THAT WAS WHEN I SAW HOW THE ENTIRE DIODE HOLDER AROUND THAT LUG HAD CRACKED, SENDING THE WHOLE CONDUCTING LUG INTO THE ROTOR AND LOTS OF OTHER WELL GROUNDED METAL AROUND IT! PROBLEM FINALLY SOLVED! Deo gratias! Gratias a Sanctus Iosephus. Amen.

From this happy moment on, I devoted myself to first cleaning up all the melted or burned insulation, then rewiring what is necessary for Mathilda to run safely and properly. Again, Deo gratias, both the field lead and ignition lead were still mostly undamaged. With a little vinyl tape and a few butt splices, those 2 vital wires were routed back to their respective destinations. I made a new charging lead from some red #12 AWG stranded THHN wire I had laying around, and used #10 AWG to replace the damaged power lead from the big lug on the starting relay going through the speedometer cable grommet to avoid the aged bulkhead connector. After carefully cutting away and unwrapping the big bundle under the dash from the bulkhead connector, I found another improvised horror in a bare crimped joint of 4 major current carriers for the lighting, ignition and accessories. I consulted the schematic from the 19665 Chrysler FSM, C 8-74, happily noted that none of the old molex connectors got damaged, routed the main power to the battery bus in the fuse box, attached the ignition to the spare male spade connector adjacent on the bus, and spliced the light lead to the breaker to a neatly wire-nutted joint left accessible by the fuse-box should I need to rip the joint apart in a hurry.

I drove on the battery to the nearby VatoZone, which had another 60 amp alternator on the shelf, installed it there in situ and drove home. The battery was fully charged before I got there, in a distance of 2.7 miles. Everything works…. BUT for some WEIRD reason, the Hot idiot light comes on when I turn the ignition key OFF. Given that I completely disconnected the sensor leads for both the temperature switch and the oil pressure idiot light, I surmise that this nasty little puzzle requires me to again remove the lower dash access cover under my steering wheel. I already cut violet #18 AWG wire designated G-2A in the FSM on the interior side of the bulkhead connector; which is no loss as both it and the grey companion, G-9 for the Cold light both WERE badly damaged by the short and had been taped off and out of use for over a month already, as I prefer mechanical gauges which actually INFORM ME OF THE QUANTITY THEY’RE ASSIGNED TO REPRESENT rather than the obvious “hot” as steam blasts out of sundry crevasses between cylinder head and block or as valve clatter and sickening KNOCKING confirm that the “check oil” light is on for GOOD CAUSE. I don’t dig idiot lights. Never have, never will.

Had I seen more than momentary voltage drop on my analogue volt gauge adjacent to the other two aforementioned, I might have attended to that damned alternator BEFORE getting the nice Standard ignition coil, and saved myself a valuable day’s labor and aggravation. But the only time this was evident was when those slight ignition stutters occurred, and they weren’t severe.

My Moral to all you fellow C-body lovers is: CHECK YOUR ALTERNATOR AS THOROUGHLY AS THE REST OF YOUR IGNITION COMPONENTS WHEN YOU HAVE MISFIRES OF ANY SORT! I’m including a pic of my old one for your final perusal. Note how the 2 diodes closest to the charging stud are actually LAYING ON THE ROTOR and how the case has CRACKED clean through below the stud, permitting this to happen. At least VatoZone gave me the core depost on the worthless thing, which was decent since the one sticker remaining on it marks it CLEARLY as ONE OF THEIR OWN.

cracked-alternator.jpg
 
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detmatt

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Spent some time in the theatre, have you??
I'm glad your car didn't burn to the ground, nice save.
 

Big_John

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I've never seen that type of failure that wasn't caused by the alternator getting dropped or otherwise physically damaged.

I'm a little too easily distracted to get through these long posts... Oh... Something shiny.....
 

Gerald Morris

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I've never seen that type of failure that wasn't caused by the alternator getting dropped or otherwise physically damaged.

I'm a little too easily distracted to get through these long posts... Oh... Something shiny.....

The former owner likely tried using it as a bong. Yes, a cracked case comes of SOME sudden impact trauma as a rule of thumb. Tightening the loose nut on the stud doubtless hastened the final break, but the one week sans misfiring convinced me that "all was well." NOW, it is, w.r.t. ignition. NOW for that front end!
 

Gerald Morris

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Well hell, Gerald, I like you already. Thanks.
Right on! I usually take the same conservative, minimalist approach to repair and upgrade I've seen in your work. I took a B.S. in electrical engineering, only to find that corporate mismanagement these daze wants PowerPoint and code whore engineering. But with old C-body Mopars, there is a whole universe to apply my study, especially the extra physics to! Again, gratias.
 

Gerald Morris

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Spent some time in the theatre, have you??
I'm glad your car didn't burn to the ground, nice save.
Political theatre, but yes, theatre to be sure! I advocate a simple brute-force kill switch for ALL sorts of good reasons. I reckon some suitable over-current protection on all the main power conductors will prevent any opportunity for an encore performance from me. After decades of ownership by the illiterate, not a single factory fusible link was left, nor replaced with anything better, so I've got more shopping to do. Breakers for the =< 30A stuff, slow-blow fuses for under.
 

Mopars & Missiles

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......I also changed ballast resistors though both of mine read between 500-700 Ohms, as specified and neither is too badly oxidized, yet….

REALLY??? If true, this is your "stutter" problem. Surprised it runs at all.

I even tightened a puzzlingly loose battery terminal on my old roundback 60 amp alternator, with apparent good result.

Perhaps over-tightened?? This could be why the case was broken and shorted??

I STILL HAD THOSE SEVERAL SLIGHT IGNITION STUTTERS!

See Ballast Resistor reading above??

The battery was fully charged before I got there, in a distance of 2.7 miles.

Do you drive REALLY slow?? In LOW gear and high RPM??

See questions inserted above. Theatrics omitted for the sake of sanity.

PS. I meant to add, I'm really glad you were able to keep your car from burning to the ground under the circumstances. Scary stuff, for sure.
 
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cantflip

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WOW... Jeff you've met your match!:poke:
Nah... He wins.... I was never competing, just trying to be useful around here. Maybe occasionally a lame attempt at humor... Oh and most importantly, thanks again to Mr. C for helping me fulfill the dream.

Its good to have another engineer around I suppose, one day I plan to post a project I have been wanting to work on. Right now I'm working on getting to Carlisle.
 

Gerald Morris

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Hmm, you're right about the resistance of course. Make those 0.500-0.700 Ohms, COLD. Just checked my running one, at 1.4 Ohms, as I had the motor running recently. My "pocket spare" read 0.8 just now. No, I've had no misfires since yesterday, and expect none for now. When pounding keys late at night, one can omit things like decimal points. My coil normally gets ~ 10.0 V just started, and drops to 8.0 V when Mathilda is all warmed up, so I'd say the ballast resistor is doing its job in the little voltage divider quite nicely.

No, I didn't gorilla arm the damned battery stud, and took care to tighten ONLY the 7/16" nut on the outside, which is for securing the ring connector to the stud. The inner nut holds the stud to an insulating washer and then the case. There was no wobble in the stud, so I left bloody well enough alone there. Still, ANY attention likely precipitated the catastrophic crackup, though I got over a week of almost perfect behavior out of the motor.

See questions inserted above. Theatrics omitted for the sake of sanity.

PS. I meant to add, I'm really glad you were able to keep your car from burning to the ground under the circumstances. Scary stuff, for sure.

Yes, and your sympathy has been duly considered and appreciated for all its worth. I doubt Mathilda would have completely torched, but the entire mess around the starter relay and through the bulkhead connector COULD have burned, and possibly shorted more components in a cascade of over-currents until either the battery ran down or the factory #8 AWG lead going from it to the starter relay finally overheated and melted through. Since I compose for folks benefit, I've corrected my original punctuation blunder so the readers will see 0.5 - 0.7 Ohms, and not 3 orders of magnitude too much! Mea culpa, mea culpa, mea maxima culpa.
 

Gerald Morris

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WOW... Jeff you've met your match!:poke:
Naa, I'm NOT the slightest bit competitive, thanks be to God. I just compose for Charity. Alternators certainly are part of C-body Mopar circuits, and warrant attention! If I save somebody $20- $50 with this post, then I'll die happy with it. Blessed be!
 

Mopars & Missiles

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Hmm, you're right about the resistance of course. Make those 0.500-0.700 Ohms, COLD. Just checked my running one, at 1.4 Ohms, as I had the motor running recently. My "pocket spare" read 0.8 just now. No, I've had no misfires since yesterday, and expect none for now. When pounding keys late at night, one can omit things like decimal points. My coil normally gets ~ 10.0 V just started, and drops to 8.0 V when Mathilda is all warmed up, so I'd say the ballast resistor is doing its job in the little voltage divider quite nicely.

No, I didn't gorilla arm the damned battery stud, and took care to tighten ONLY the 7/16" nut on the outside, which is for securing the ring connector to the stud. The inner nut holds the stud to an insulating washer and then the case. There was no wobble in the stud, so I left bloody well enough alone there. Still, ANY attention likely precipitated the catastrophic crackup, though I got over a week of almost perfect behavior out of the motor.



Yes, and your sympathy has been duly considered and appreciated for all its worth. I doubt Mathilda would have completely torched, but the entire mess around the starter relay and through the bulkhead connector COULD have burned, and possibly shorted more components in a cascade of over-currents until either the battery ran down or the factory #8 AWG lead going from it to the starter relay finally overheated and melted through. Since I compose for folks benefit, I've corrected my original punctuation blunder so the readers will see 0.5 - 0.7 Ohms, and not 3 orders of magnitude too much! Mea culpa, mea culpa, mea maxima culpa.

Was hoping that was a typo, yes 0.5 to 0.6 ohms is the proper ballast resistance for your car, so you should be good there. There are resistors for later model cars that are 1.0 ohm and I believe also some 1.5 ohms as well. Then there are the "dual" ballast resistors that introduce a whole other set of values, we won't get into those.

As for the alternator post, don't know how big of a gorilla you are? Some folks could do that kind of thing and be none the wiser for it. I agree with a previous post, that kind of damage is usually caused by some type of impact or dropping onto concrete. Maybe the casting got cracked when it was being rebuilt previously and only now after who knows how long and how many miles did it finally break completely??

Bottom line, you were able to save the car for another ride, another day. :steering:
 
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