Alternator 10Valve Avant

The alternator in this 1990 200 Avant case was a 110 AMP Bosch unit.

I needed these tools:

Pry bar or pipe

8MM Box wrench

13mm Box wrench or rachet and a 13mm socket for 3/8 drive

NEW star wheel adjuster & bolts.

Continential Belt:  11.2MM wide and 820 MM long.

The older Conti replacement was 10mm wide x 825 mm long....

Parts:  Some serviceable.

Brushes Replaceable


Contact terminals for power leads (wires)

  Ignition noise suppressor?

Where the air shroud below screws in.

Air shroud.

DISCONNECT the battery!

Below is the view looking up from the ground.

Notice the bolt sticking out.  Behind the alternator way up high is another nut to deal with.

Replace the star wheel adjuster and refer to the Bentley service books

for how to properly tension the adjustment bars.

The "star" wheel below, behind and at the AC unit need

to be loosened then tightened to properly tension the belts.

On the 10V I removed the Michelin Man hose for an easier view.

Here the alt hangs on the BEHIND the alt "star" wheel.  Oil filter is Blue.

Here I check the belt tension during tightening it up.

I found prying against the alt to take up the slack,

was the way to set the alt, then use each of the star wheels to tighten the belts down.

These are the brackets from a 1991 200 20V Sedan and Avant for comparison:

Alt: Edge of photo on Left.  A/C on right.

Closer photo of the A/C bracket. 

Notice the star wheel adjuster has a outer edge a bigger wrench can fit on.  Use this to tension.

Use the smaller 13mm? bolt to "hold" the tension setting.  It can strip EASY!