Just doing oil / filter changes on my Volvo Penta D2-55 and the oil filler cap is really hard to access - the deck is very near above it. however there is another apparently oil filler cap by the stop lever. Anyone know what that is for? http://rubble.heppell.net/media_forum/D2-55.jpg

 

That's your diesel injection pump. Emergency stop lever and maybe an air bleed?

 

That is the oil filler cap for the engine. On that series of Volvo Penta engines the fuel pump assembly is part of the engine block. The water pump and I believe governor are located in the assmbly to the right of the fuel pump. You can see the separation plate/gasket between the 2 assemblies