Alternator Installation Failure Report and Analysis 

Mar 2022 R. Kwas [Comments added.]

An Amazon owner has experienced a catastrophic failure of his retrofitted Delco Alt on a SW-EM Alt Mount.  This was apparently associated with a suicidal Alternator which decided to shed some of the screws that hold the Alt together (or are supposed to!) and these getting lost...the Alt then doing its best to disassemble itself!!, which resulted in so much vibration and movement, that the rear pedestal of the mount broke away. 

Thankfully, Richard heard and investigated the "new noises" coming from the engine compartment, and upon finding the Alt in the partially disassembled state, was able to use the single remaining bolt to somewhat hold things together, and limp to a place where more serious repairs could be undertaken.  Apparently though, there was enough movement during the long "limp to safety", that the rear pedestal of the mount still fractured and failed. 

Richard also happens to be a Mechanical Engineer, so he was instrumental in analyzing the failure and providing additional info helpful for documenting the case.

Richard Barnes pictures, posted with his kind permission. 

Emergency repairs in progress...


These are the only pictures Richard was able to take upon investigating the new noise...he was focused on other things...! 


Aftermath of a suicidal Delco Alt...not much to see, but the Alt failure has involved the bracket to the extent, that its rear pedestal has clearly separated above the weld, staying with the Alt! 

The full story and detailed Update  (by Richard Barnes) [My comments added]:  

"  I wrote about my inexperience when I got back to New York and the memory was fresh.  A bit long winded. OK. [Join the club!] The order of events and discovery doesnít necessarily point out the origin point.  A list of damages:

 - The alt through-bolts holding the 2 casing halves together broke or went missing. [ I would say loosening and loss of these bolts is the prime failure.]
 - The regulator is damaged. [Secondary damage...]
 - The bearings were dry. [ I would say this is a contributing factor!]
 - The internal wiring was not soldered (not damaged but below expected standard). [...a side-observation.]
 - There were signs the rotor and stator impacted each other.  [...more secondary damage, once the bearings go away and case halves were allowed to dance and misalign. ]
        Not a consistent groove but a series of short gouged lines. 
        I recall seeing 4 in progressively smaller lengths from maybe an inch to a half; quarter etc. 
        I might disassemble to look again when I have spare time.
 - The rear securing part of the bracket broke off when removing the alt  [...also secondary damage...]

We were up in the Catskills The previous weekend.  On Sunday, while in a nearby town, I heard an unusual sound from the engine as I was leaving a parking lot.  I stopped and looked.  My AC Delco alternator was the cause of the noise.  The casing halves were visibly vibrating!  The gap that separates the 2 looked about to open right up.  After I shut her down and inspected I found 2 of the 4 through bolts that hold the 2 halves together missing!.  Scary.

Fortune had me at a massive parking lot ringed by Ace Hardware, Walmart auto and Home Depot.  Actually - hope but no fortune as the time spent looking for a remedy of any sort, such as a substitute for through bolts, was wasted.  Luckily I had a bolt of the right size in my stash of fixings.  I loosened the alt and threaded it into one of the bolt holes.  (Understand, it was vital that the car could transport us.  The best solution of not driving until proper repair is outside my pocket.  A 50 minute Uber would be a small start).

I was anxious and wary but kissed the heavens for luck that 3 bolts might keep her together.  At least back to the hills where Joyce was.  Better for me if the car dies up there and us together than for me not coming back at all that night.  I may as well be dead meat!  Going back I was listening to my engine and to me I was hearing the sounds of a í70ís Pontiac engine.  That whining noise, but not the sound of a belt. When I arrived and popped the hood would you believe- the 2 remaining original through-bolts were gone!  The casing was held together by my single bolt.

I woke early the next morning and started calling parts suppliers and mechanics.  Itís always amazing to me how mechanics refuse to accept that the internet exists!  I get hating the thing.  But itís 2022.  We all have mobile phones whatever we feel about them.  (Right?). No one is looking in the Yellow Pages!  Local mechanics are not showing up in my googling and other searches, as usual.  America is littered with small mechanics shops of every type and formality but there isnít any indication online.  And when I talk to local mechanics in my travels they bemoan the loss of business.

The big suppliers 30 miles around had no available options.  No alts for me.  No repair kits.  Junk yards didnít have cars from the previous century!  Wow!  It was the 15th mechanic/body shop/motorcycle shop that couldnít help me but finally did know a guy that rebuilt alternators.  Mikeís Powerhouse.  Hoorah!  And just 10 minutes drive if I dare it.  But broke down where I was would be little better than 5 miles down the road.  I think itís the same result.

Mike's Power House wasnít in the business of rebuilding 50 year old automobile alternators and generators.  He works more with heavy duty machines.  He was able to reassemble everything from base, new bearings but not a new starter, armature or, most importantly, regulator.  That doesnít get me all the way to fixed but it does reduce the likelihood of engine parts dropping from under the car on the highway.  Mike showed me the internal electrical joints were crimped, not soldered; the bearings were dry;  all the through bolts were gone.  One half was left in a hole.  There was damage on the stator from some impact.  He tested the alt on the bench and in the engine. Things seemed good enough.

I didnít take notice when I had the alt off at Mikeís.  But taking it off a few days later for replacement I saw the AC Delco sticker was on it.  I found the 1 year warranty card later.  This was the correct purchase.  About 3 years old now.

In the last few miles back to Brooklyn I saw the voltmeter climb above 15 a few times depending on what the engine was reving at and what was running.  I had to use the wipers and headlights part ways.  When I parked I could hear the alternator struggling.  Iím not sure what makes the sound but it seems like friction of some sort.  No further external damage to see. 

I ordered the new alternator from Rockauto.  Then I went out to remove the alt.  I removed the lower bolt most of the way and went up top to finish removing the top securing bolts.  As I held the alt in my hand after removing the top bolts it seemed to move off kilter.  I pulled the lower bolt the rest of the way out, pulled the alt out and found the rear securing piece of the bracket had fallen on the ground.  I believe it broke off when I pulled the alt away from the car.  I felt it was still there when I unscrewed the bolt and was pulling the alt away from the engine. 

The bracket came off the block as expected.  No loose bolts.  The belt is in fine condition. 

How things unfolded and the order of broken parts I found does not indicate what the actual source of all the failed parts. I donít believe there is any defect with the bracket.  I have removed the alternator a few times since it was initially installed and I always refer back to the original installation notes as I may forget a step.   It might be an issue in the alt or a problem with the bracket installation. I have considered that if a bolt was not secure (which I did not find) the bracket would vibrate and the alt would wear at the bearings and bolts. And those problems would extend further. Itís possible things came in the opposite direction. 

It might be a defect in the alt or a problem with the bracket installation. I have considered that if a bolt was not secure (which I did not find) the bracket would vibrate and the alt would quickly wear at the bearings and bolts. And those problems would extend further. Itís possible things came in the opposite direction. 

Themís the details.  Hopefully part will be here today or tomorrow.  I will update you when it arrives.  Thanks for the materials and the call.  Wish I had been able to meet up last weekend.  Next time for sure. 

Richard "

Replacement Alt installed on a new bracket. 

[End Of Richard's notes.]

Pictures of the offending Alt once Richard got home.  New bolts hold the cases together and internal repairs courtesy of "Mike's Power House".  The Pivot boss shows some signs of vibration wear.  Evident also is an official looking AC-Delco sticker...the Alt doesn't particularly good or bad...but it's clearly what's inside that counts!

321-264 is one of the Alts recommended for installation with the conversion. 


321-264 is a 12SI unit as evidenced by the closed cooling air centrifugal impeller.


The pivot bolt exhibits only slight signs of wear. 


Reference:  Link to Bolt Ratings


UPDATE:  Richard has sent me the (now two-part!) failed Bracket for inspection.

Inspection of failed bracket SN P04 (after approximately 2 1/2 years of service, and failure):

On first look, there is not much more than the obvious broken away rear pedestal.  Of note is that it broke above the weld, showing that the weld itself was stronger than the base structure...that's good!  He did not also include the pivot bolt...only a picture.  Sometimes, things can be learned from it also...  What I am always on the lookout for in situations like this, is evidence of long-term galling as an unmistakable result of relative vibration of surfaces which should have been immovably clamped together...

Front of Bracket...besides the obvious fracture, which is a secondary resultant of the heavily vibrating Alt, otherwise looks typical for having been in service for a while on a car parked outside in New York.  


Backside of Bracket

Rear of Bracket doesn't look particularly bad either...front (left) hole is not painted, as it is the main output current return path.  The middle hole has paint worn away from slight vibration, and the rear (right) hole still has remnants of paint.  


Detailed inspection:  

Besides the obvious break above the weld, some (limited) galling is evident at the rear mounting surface of Alt Pivot.  This is not unexpected given the amount of vibrating the Alt Housing was doing after separating...the important thing to note is that it does not look like it was occurring for a long time...likely only after Alt Housing separated and the assembly became totally unstable.  


Very little, if any galling in evidence at the front Alt mount. 


Only minimal surface galling (with no depth perceivable with a fingernail!) is in evidence at the front bracket-to-engine mount hole...the worst one!  The other two only exhibited very limited evidence of any movement.  


Conclusions:  Bracket to engine and Alt to Bracket show no extraordinary signs of prolonged vibration leading to galling, so prefailure of the Alt, the Bracket and Alt installations were as they should have been and without issues.  The problems would appear to have been caused by the Alt housing halves themselves coming apart (not helped by the fact that the internal bearings were found to be dry on inspection) it would seem that this failure can be attributed to a suicidal (allegedly "rebuilt", but not particularly well!) Alt.  

Lesson learned:  Know and trust your suppliers and check the 4 screws which secure Alt case halves before installation!  Always listen to the noises, and investigate new ones!  Beyond checking those four screws which hold the Alt Housings together, I don't see anything learned here that can be directly fed back into the kit installation instructions or notes.

Richard's Tip:  Assure the four bolts which secure Alt Housing halves are in good condition and tight, and always investigate new or unusual noises!

Finally:  Keep your receipt and guarantee documentation! 


Thanks to Richard Barnes for the pictures and cooperation in this failure analysis.  Otherwise, this article is Copyright © 2022.  Ronald Kwas.  The terms Volvo and AC-Delco are used for reference only.  I have no affiliation with either company other than to keep its products working for me, help other enthusiasts do the same, and also present my highly opinionated results of the use of their products here.  The information presented comes from my own experience and carefully considered opinion, and can be used (or not!), or ridiculed and laughed at, or worshipped, at the readers discretion.  As with any recipe, your results may vary, and you are, and will always be, in charge of your own knuckles, and future! 

You are welcome to use the information here in good health, and for your own non-commercial purposes, but if you reprint or otherwise republish this article, you must give credit to the author or link back to the SwEm site as the source.  If you donít, youíre just a lazy, scum sucking plagiarist, and the Boston Globe wants you!  As always, if you can supply corrections, or additional objective information or experience, I will always consider it, and consider working it into the next revision of this article...along with likely the unique metaphor and probably (likely) wise-a** comment. 


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