Buick 12539085 Piston (WithPinion)

Prior to removing the piston and connecting rod assemblies, the cylinder head(s), oil pan, and oil pump must be taken off, depending on the engine type. First, use your fingernail to check for any ridges at the upper limit of ring travel, which is about 1/4-inch down from the top of each cylinder. If ridges are present due to carbon deposits or cylinder wear, they must be completely removed with a ridge reamer before attempting to remove the pistons to avoid breakage. After removing the cylinder ridges, turn the engine upside-down with the crankshaft facing up. Before removing the connecting rods, check the endplay using feeler gauges; if the endplay exceeds the service limit, new connecting rods may be necessary. Ensure the connecting rods and caps are marked for identification, and if not, use a center-punch to create indentations. Loosen the connecting rod cap nuts gradually until they can be removed by hand, then take off the number one connecting rod cap and bearing insert without dropping the insert. To protect the crankshaft journal and cylinder wall during piston removal, slip a short length of plastic or rubber hose over each connecting rod cap bolt. Remove the bearing insert and push the connecting rod/piston assembly out through the top of the engine, using a wooden or plastic hammer handle if needed. Repeat this process for the remaining cylinders. After removal, reassemble the connecting rod caps and bearing inserts in their respective rods and install the cap nuts finger tight to prevent damage to the bearing surfaces. It is important not to separate the pistons from the connecting rods.