I saw a post about crap starter motors on these engines.
My dad has this motor in his river boat on the Thames. Last week he went to start it and the starter did not disengage from the flywheel ringear so the engine spun the starter. This was only noticed by the smoke coming from under the engine cowling.
Mercruiser wanted some silly figure for a new starter, So i went down to the local motor factors. Asked for a Vauxhall Astra mk4 diesel starter motor. I can tell you the starter they gave me is identical in every way to the Mercruiser one, just not painted black. At £69 is a bargain, and works perfectly, just a sod to change.
I also had starter failure on my uncles RIB which has a VW 150hp tdi inboard (straight out a VW Transporter van), only the solenoid would not engage. I put it down to the fact that car derived engines have the starter located at the bottom of the bellhousing right in the damp of the bilge. Luckily this boat still has warranty on the engine, so is being done by RK marine. The starter on these VW engines requires the engine to be removed from the boat to be replaced!
Glad im not paying for it!