We pulled out a piston (the black piece in the center). The shining rod is the piston rod with the (black) stuffing box. This motor had 7 pistons and one we had in spare.
Some oilers are cleaning the LT-cooler. On most ships, the sea water is cooling the low temperature (LT) fresh cooling water, means indirect cooling. The LT-cooling water is cooling the lub-oil and the high temperature cooling water.