Fluid Reservoir identification

[Blentz17]

Alrighty folks, I have another novice question for this 488 3.7 mercruiser. What is the fluid reservoir for that sits right behind the top flywheel and in front of the oil pan. Im used to dealing with outboards so this set up is a bit new to me. I have looked at many engine diagrams but have not had much luck.

 

[racerone]

Closed loop cooling system.

 

[Blentz17]

Closed loop cooling system.

 

[Blentz17]

Thanks for the response, I’m clear on the cooling system, I just wanted to clarify that I was not talking about the pan, the fill resavoir Is located on the transom. I’m trying to identify this resavoir, see circled pic for reference

 

[Scott Danforth]

power steering pump