Just bought this new lifetime warranty alternator from NAPA. They took the fan and pulley off the old alternator and installed them on the new one. Great SERVICE NAPA!

They also had in-stock new metric bolts that I will use to replace the bolt I beat up during the extraction process. Then went to Home Depot and bought some nice spacer washers for the new metric bolts which should help.

Question: If I wrap the alternator in a plastic bag to seal the intake vents from metal particle ingestion, could I use a dremel tool with a metal cut off wheel to shorten the length of the four bolts that hold the alternator together? I'm thinking cutting the bolts off would make it easier to work with the alternator when it is installed on the car.

BTW, went to another car parts place and their receipt noted that there are NO returns on ANY electrical components.....quite different from NAPA's lifetime warranty to the original owner!

Note the location of the electrical connection on the back of this NAPA alternator is somewhat different than the standard Bosch units.....

Attached Thumbnails

     

You might have trouble returning it to NAPA if you cut the bolts off.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Yes no return if tamperd with.Also thats not right ,bolts dont srick out of new lifetime alternators . Dont understand this,, something isnot right.

The bolts are threaded , and the alternator case is also . The bolts should be flush to the aternator case.The bolts should not stick out .The service centre was short of the right length bolts and put a one size in .Take it back and get them to sort it out.Not your job to ,as its wrong. Look like a china job.

Before leaving the building it is a good idea to ask them to test the Alternator for you even if it is a rebuilt one.

Re-confirming it is a good before you install it can help you troubleshoot if after the installation you are still not charging.

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84 300D, 82 Volvo 244Gl Diesel

Looks like those bolts are for the shield.

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'85 300D Cal 280,000 miles
'14 GLK 350 60000 miles

Since its warrantied, bring it back. If it wasn't, my suggestion would be to take out all four bolts, and either trim them or replace them, but not to cut them in place. At the same time, you could rotate the case to the correct clocking.

I replaced the nearly seized factory alternator on my Mazda with a rebuild a few years ago and the first rebuild I had put out like 20 volts from the first time it was started. It caused my dash lights to be extremely bright, so I knew right away something was wrong. It blew both my fog lights but thankfully nothing else electric was damaged.

Had to take it back to the store and they tested it and their test said it was ok. Ended up swapping in the broken alt again to make sure it wasn't my car, had to bring rebuild alt back to the store a second time and talk to the manager for a long time before he exchanged it and then put that one in.

So ended up having to remove and install an alternator three times, and it's an absolute pain in the arse job on the Mazda. This second alt has been holding up but it makes a high pitched whining noise (not the belt) whenever I use a bunch of electricity (head lights and rear defogger for example)

TL;DR
Rebuild alts suck and don't trust the store test. Don't cut the bolts on the one you have: with rebuilds it's an almost absolute guarantee you WILL have to use that "life time warranty" at least once, so make sure the unit stays in a returnable condition. Rebuilds are much, much cheaper than factory units and now you know why.

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"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

What is "correct clocking"?? Doesn't the alternator come from the factory set up correctly?

The back cover (which includes the stator and diode bridge) can be installed in any one of four positions. Since the connector isn't in the right place for the harness, this is fixed by removing the bolts and rotating the case.

Bring it back. It should not be that way.

But if you had to, this ^^^.

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1983 123.133 California
- GreaseCar Veg System

Those bolts should be that way. Its not a problem with manufacturing. The bolts are for the 1985 California model that has an extra heat shield that goes on the back of the alternator. This is the superseded part and is currently the only one that's available from the ORIGINAL supplier. Alternators from other suppliers that have the flush length bolts are either old stock or are of their own casting & manufacturing (non-oem).

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1985 300TD - "Panzer Wagen" - undergoing full restoration (resto - mod)
2014 GLK250 Bluetec - Wife's car

Mercedes-Benz Master Certified Technician.

http://www.flickr.com/photos/joshuajeeper/

I'd return it based on this pic alone. The regulator is a cheap, non Bosch unit.
How do I know? An alternator rebuild place gave me one for nothing and it does not look well made. Very different design than Bosch, with parts potted in Epoxy. I'd return it for one with a Bosch regulator.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Took your advice and returned the alternator to NAPA. I sourced a genuine Bosch 65 amp unit which should arrive in a few days. Since this experience, I am planning on obtaining an extra alternator and extra starter for both cars. Sure, they'll sit on the shelf but if either goes out on the car, I can simply grab one off the shelf and install......minimum down time.

The brushes on the regulator is the only part that wears. The electronic components do not wear out. Actually, they have been "burned in" and are less likely to fail than a new one.

The brushes on the Bosch regulators cannot be un-soldered with a regular iron and has to be drilled out, then the new brushes can be soldered on. Bosch use a very high temperature "solder". This is a tip from the alternator rebuild place that gave me the cheapo regulator.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked