The new Bosch AL-117X 65 amp alternator came in. I took off the pulley bolt and noticed the shaft does not have a notch to fit the original keyed fan and pulleys.

As a trial, I placed the notched fan and pulley on the new alternator then turned the pulley. It appears to drive the alternator but I don't like the idea of the shaft not having a notch to fit the fan/pulley. I need to put this car back on the road today, any ideas are appreciated.

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On this forum people have occasionally reported the same. It is also not uncommon on other makes of alternators.

Personally I don't mind degreasing the Fan and Alternator Shaft with Brake Cleaner and putting a little slow curing JB Weld on the Shaft and I generally use an electric or pneumatic impact wrench to tighten rap the nut with no hold on the shaft or nut.

JB Weld is good for about 250-270 degrees F. That means when it comes time to remove the Far it is easy to get the JB Weld to release if you use a Propane Torch on the Fan. The JB Weld softens or burns and the fan comes off. A wire brush takes off the old burned epoxy.

People that had rebuilt alternators when the got the Car and later took them off to replace a bearing have said there was no Key and they did not suffer any pinning of the pulley. However, I have not seen anyone post a specific torque for the shaft nut and I have never looked for a torque.

I slso use loctite on the shaft nut. But, I normally am reusing the shaft nut.

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84 300D, 82 Volvo 244Gl Diesel

OK, mixed up some JB weld and placed it on the drive shaft, then washer, then fan, then pully. Then placed Loctite on the threads and placed washer on then tighted the nut using a 24mm wrench.

I held the fan with my hand while tightening the nut; question, is there a better way to hold the fan steady while tightening the nut?

The keyways disappeared years ago. Just snug in the bolt nice and tight, and it won't be a problem. JB Weld is a bad idea...it's not likely strong enough to work, but if it was, you'd have trouble removing the pulley in the future.

The internal hex in the end of the shaft is not there as a decoration.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

You can also cut a groove in the shaft using a dremel, and insert a woodruf key.

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1998 E300 turbodiesel

America's Rights and Freedoms Are Not The Enemy!

The torque for the flange nut on the newer alternators with the internal fan is 80 NM.
I don't have the spec for the external fan but probably similar as they are both 16 mm threads.

Special thank you to everyone who assisted. I finished the car up around 4:00 PM today. My main concern was a loud noise that was developing from the engine area after driving the car 15 miles or more. It was the EXACT same noise the last time the alternator bearings went out. Now, it is quiet as a mouse. YES!

I had same issue when replacing alternator on 1984 euro 300D OM617 about 5 years ago. I also used a Bosch and torqued it tight and so far it hasn't slipped and never a problem with voltage. Please let us know if you discover more as I would like to replace with a keyed version if possible.

Absolutely not necessary.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

The key was removed in design. The taper on the shaft holds the pulley tight,

This design is also used in old VW diesels to lock the camshaft pulley to the camshaft itself. Works a treat if the surfaces are clean and the torque applied is correct.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Key shafts went away on USA domestic cars in the 60's, absolutely no need for a key.

However, I see a strong possibility that the hand tightened by holding fan / epoxy / locktite mess will come apart down the road.

The no key shaft works fine when the nut is torqued to spec as the pulley is trapped between the nut and rotor. Our guy hand tightened the nut so eventually the pulley will fret and spin on the shaft. Being the nut was locktited the nut will still be in the original position ( RE the nut didn't back off, the pulley got thinner from wear. )

At that point our guy posts that all non keyed alternator shafts are doomed for failure, when in reality it was an assembly error.

I have never seen a tapered shaft on any Alternator. Also once the nut is loose the fan is loose except for any rust.

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84 300D, 82 Volvo 244Gl Diesel

Truth is that it's a crappy design. The nut has to be tightened to 50 lbft (70 Nm), otherwise the momentum of the core could twist out the nut. But the shaft is soft, so you can't just wail into it with an impact wrench or it will fret and loosen. A dab of low strength thread locker and a new lock washer wouldn't hurt. Or use a decoupling pulley. But put the JB Weld in the box with your duct tape, it's not going to help anything.

That's a stretch, millions upon millions of non shaft key alternators are happily spinning along the world over.

There is rotor inertia to consider and the rapid stop of a diesel could cause the nut to work loose if it was not tight enough in the first place. However, that is a failure caused by improper assembly not a design failure.


Using an impact to tighten is the real world solution used by shops the world over, seems to work well enough.

Fretting will only occur if there is relative motion between the shaft and pulley. A non locktited nut would tend to tighten during use rather than loosen. Think about a hand held grinder wheel or a sanding wheel, these can be tightened without tools and won't come loose

The issue with our JB weld on shaft / locktite nut guy is the nut is glued to the shaft and won't try to tighten as the pulley starts to spin on the shaft.