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Damn was getting ready to do the WT ground mod and noticed the upper mount tab is broken on my Alternator.  It's a bosch.

 

Are the bosch and denso alternators interchangeable?  I've been shopping around for a replacement but seems to  be some confusion about the correct alternator, depending on the eighth digit of the vin. ( in my case it's "C")

 

Advance auto has the actual bosch alternator (based on the alternator part#) but the listing says it's for trucks with a vin: 7 https://shop.advanceautoparts.com/p/bosch-premium-100-remanufactured-alternator-al6400x/20851271-P?navigationPath=L1*14920|L2*14999|L3*15587

 

Rock auto has an alternator for vin: C, the listing says its a bosch, but the pictures are denso.  https://www.rockauto.com/en/moreinfo.php?pk=5778228&jsn=3

 

Rock auto also has an alternator for vin: 7 and the pictures of it are bosch:  https://www.rockauto.com/en/moreinfo.php?pk=273175&cc=1441320&jsn=2096&jsn=2096

 

I called a dodge dealer, they said item is discontinued but at least gave me the part# 5104772AA  BUT a google search of that number brings up a denso alternator.

 

A search of the actual part number on my alternator brings up a bosch:  0124525005

 

Which one should I use?  Why is it everyone says my truck vin: "C" should be denso, but my truck has a bosch?  Ok so there is a chrysler emblem on my bosch alternator, but who's to guess if it's the original factory alternator. Sure is old and beat up looking regardless.

 

 

While I was in there I noticed the large positive cable that connects to the alternator (B+)? was rubbing against the top of the alternator body, wire insulation partially worn through. Glad I caught that before shorting out.  Pictures:

 

 

 

 

 

 

 

alternator bracket.png

alternator wire.png

bosch alternator3.jpg

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Interchangable. 

 

Bosch and ND alternators will both fit. I just had this happen on my landlords truck at my other shop. Did the W-T ground wire and pulled the alternator and the nut broke off the top bracket. 

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Personally, I would not be that concerned about the broken ear on the alternator.  There is still plenty of material left on the ear to allow for a good clamp.  The reason the mounting ear failed is because the clamping fastener had lost its tension a long time ago.  Once the tension was lost, the fastener beat against the mounting ear relentlessly at the frequency of the running Cummins engine. 

 

As long as there are no cracks in the remaining part of the ear mount, I would re-use the alternator.  Just check periodically that the fastener remains tight. 

 

- John

Edited by Tractorman
always something
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I'm replacing this alternator and the mounting bolt.  Who knows how many miles it has on it anyway. Could be 230k if it's the factory unit. Getting ready to haul a car trailer next month, can't take chances.

 

Looks like it's been bouncing around for a while, the bolt is worn quite a bit:

 

 

 

 

alternatorbolt.jpg

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10 hours ago, dripley said:

We have twins.

Good one! I guess it's not a coincidence then.  @dripley how many miles were on your truck when this happend?

 

I'll be checking this more often, like every oil change. I'll see if I can scribe a mark on the mount bracket for future reference to observe if the alternator body is moving position.

 

Good bet there are other trucks out there with this issue without knowing it. Might be worth pulling the bolt to inspect & replace if worn.

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1 hour ago, Ironforger said:

Good one! I guess it's not a coincidence then.  @dripley how many miles were on your truck when this happend?

 

I'll be checking this more often, like every oil change. I'll see if I can scribe a mark on the mount bracket for future reference to observe if the alternator body is moving position.

 

Good bet there are other trucks out there with this issue without knowing it. Might be worth pulling the bolt to inspect & replace if worn.

About 260k. Never had that happen one before or since.

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340,000 on original alternator and no issues, BUT very early in its life that very bolt was loose.  I tightened it and it never loosened again.  That bolt has to be tightened to the point of distorting the ears on the mounting bracket enough to actually make them clamp onto the mounting ear on the alternator.  I think that is why some fail and some don't. 

 

@Dieselfuture is correct... you had better eat your Wheaties first.

 

- John

Edited by Tractorman
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