Mercury 1L2Z-6108-AA Piston And Pin Assembly

Use your fingernail to feel if a ridge has formed at the upper limit of ring travel (about 1/4-inch down from the top of each cylinder).

After removal, reassemble the connecting rod caps and bearing inserts in their respective connecting rods and install the cap nuts finger tight. This helps prevent the connecting rod bearing surfaces from being accidentally nicked or gouged.

Before removing the main bearing cap assembly and connecting rods, check the connecting rod endplay with feeler gauges. Slide them between the first connecting rod and the crankshaft throw until the play is removed. Repeat this for each connecting rod. The endplay should measure between 0.005 to 0.015 inch (0.127 to 0.381 mm). If it exceeds this limit, new connecting rods will be required.

Employ a piston ring groove cleaning tool or a section of a broken ring to clear carbon deposits from the ring grooves without damaging the metal.

If the clearance is not correct, check for dirt or oil between the bearing inserts and the connecting rod or cap, and recheck the journal diameter. If the Plastigage was wider at one end, the journal may be tapered.