differential tool
 

What size is the star socket to check the differential oil?
Dwight

ericnguyen
Senior Member

Registered: Jan 2003
Location: California
Posts: 484

It's either 14 mm or 17 mm Allen hex for MB cars even though most of them have 14 mm. Do NEVER use anything else (e.g. a torx) to open these differential plugs. They are very tight and you will destroy them with your torx.

Eric

Right, not a 'star', it's a hex. Well, unless things have changed on newer models...

There is a lower hex bolt on the side of the diff and a star bolt at the top in the back. '89 420 SEL
Dwight

Both the fill and drain plugs are 14mm. The drain is on the bottom on the right side and the filler plug is on the rear cover.

Loosen the "fill" plug first. If you can't get it off, then don't drain.

Also, try and remove the vent plug on top and clean it out with brake cleaner.

:-) neil