Mercruiser 7.4L - Cleaning & Checking The Engine Block


After the sediment was cleared from the engine block, I cleaned the pistons and removed one of them for inspection.  Here is a picture of the piston surfaces cleaned.  Also, there was a fair amount of rust on the engine block that needed to be removed in preparation for painting the engine during the assembly stages.

Here is another picture of the engine block (right side).  At this point of the project, the engine block was stripped down to its basics.

Notice that the area underneath where the engine mounts are fastened looked like it had never been painted.

Removing a piston:  I removed piston #4 to check for any signs of wear in the cylinder walls, the piston rings and the bearing surfaces.  Below are some pictures from the piston removal.  Everything looked really good.  So, at that point I decided to leave well-enough alone and not do a lower-end rebuild.

A view of the cylinder walls and the actual piston.

Once I decided not to do a lower end rebuild (i.e. not to replace ring and bearings), it was time to button things back up and move onto other parts of the engine that needed to be checked.  The timing chain was the next on the list.  Click this link to see Replacing the Timing Chain .