PeachParts Mercedes-Benz Forum - View Single Post - Installing An Upgraded 80 Amp Alternator And 9-Blade Fan In A 1980 W116 300SD

Squiggle Dog · #3 02-23-2013, 08:31 PM

I removed the 80 amp alternator from a W126 V8 car, so it has only a single belt pulley. Mine uses a double belt pulley, so I had to swap them out. It's not the best way, but I was able to remove the nut on the 55 amp alternator by wedging screwdrivers between the fan and body.

The nut on the 80 amp alternator was easier because the shaft has a spot to insert an 8mm hex key socket. I didn't have a socket or wrench large enough to fit on this larger nut (larger than 23mm, smaller than 27mm), so I was forced to use an adjustable wrench. The 80 amp alternator lacks the Woodruff key and relies on tightening force of the pulley nut.

I was able to fix the positioning of the electrical connections and voltage regulator by removing the four screws that hold the two case halves together, loosening the ones at the front bearing behind the pulley area, then rotating the case halves 180 degrees. You have to press down hard on the screws and be extra careful so they don't round out when you turn the screwdriver/socket when loosening.

I decided to do a test fit of the 80 amp alternator, 9-blade fan, and pulley. The 10X1035 belts I was using were very loose even with the tension screw fully tightened (due to using a smaller fan pulley). I loosened the power steering pump and removed the belt in order to test a smaller, 10X1000 fan belt I removed from a 1983 300SD, from which the 9-blade fan and small pulley came.