namasgt

Hi,

Replacing the alternator on my 88 S4. The replacement unit does not come with fan and pulley, so I have to use the old ones. Does anyone know what is the proper torque spec for the pulley/fan assembly nut? I'm finding 60-70 NM for similar Bosch alternators.
I want to do this right because some are saying that if you over tighten you can damage the bearing??

Thanks for any replies.

Leon Speed

I would like to know how to apply the correct torque. It's darn hard to counterhold the fan. Using the hex key in the axle makes the nut hard to reach. Best I could do was 'nice and tight'.

namasgt

You can hold the pulley using a long bolt/extension/big screw driver between the fan fins and the housing opening. Make sure to use the base of the fin instead of the tip since you could slightly bend the fin. And make sure to not damage any of the wires inside the alternator.

dr bob

I went with 'rattle-rattle-rattle' tight with the Makita cordless electric impact gun. It's still on there a couple years later. Same number of rattles that it takes to remove lugnuts on K's 4Runner, a definitive answer.

Reality is that there's only one good way to get a proper torque reading on that nut: the box-end wrench on the nut, and put the wrench in the vise. Then an Allen driver on the torque wrench, and back the armature up into the nut to your target torque. I'd be way comfortable with anything in the 35-50 lbs/ft range, based on the thread size and the duty. Maybe a drop of threadlocker, secure in the knowledge that it will take another impact driver and a few more rattles to get it loose in another 25 years. YMMV, etc.

I'm not at all a fan (.....) of the screwdriver-through-the-blades method. Something always seems to end up bent or scratched when the screwdriver slips. Then there's the foul language that annoys the neighbors, plus the blood and all those Band-Aids.