GM 25527178 Piston, W/Pinion(Std High, Limit)

Before removing the pistons, inspect the cylinder bore for a ridge felt by hand. Use a ridge reamer for that purpose. To start piston removal, you need to match each connecting rod cap with its respective rod number. Place a rubber hose over the connecting rod studs on the crankshaft and cylinders so they don't get scratched or damaged. Then, lubricate the cylinder wall with clean engine oil and tap the piston gently out using a wooden dowel. Repeat for all pistons in the same way. After taking them off, clean cylinder bore and pistons thoroughly using soap and water before applying clean engine oil to prevent corrosion. The piston rings are removed using ring expander tool then piston grooves are cleaned. Cylinder bore diameter and piston clearance are measured by telescopic gauge in combination with micrometer. Piston should be marked for reference. Pistons having pressed-in wrist pins must be removed using special tools while snap-ringed pins can be taken out through use of screwdriver. Replace / install wrist pins as required. When you fit in new rings, make sure they do not get damaged by utilizing piston ring expander. According to manufacturer's instructions, place the rings correctly on the pistons just as directed by their manufacturers' manual guides . In case of any damage or wear-out, inspect and replace connecting rod bearings when necessary. Use Plastigage® to check bearing clearance. Choose appropriate undersized bearing shell where necessary if there's an excessive clearance . Observe proper side clearance between rods and crankshaft in installing bearings, pistons, and connecting rods as per manufacturer specifications . Finally, reassemble engine components including oil pump(s), oil pan(s), cylinder head(s) and intake manifold(s).

Before removing the pistons, inspect the cylinder bore for a ridge, which can be felt by hand. If present, use a ridge reamer to carefully remove it.

It is essential to check the connecting rods for twist, bending, nicks, or cracks. Any issues found will necessitate replacement.

Remove the nuts on the connecting rod stud in sequence and lift the cap off the crankshaft.

Cover the connecting rod studs with rubber or plastic tubing.

After removing the ridge, crank the engine until the piston is at the top of the cylinder, then remove the cloth and cuttings to avoid damaging the piston rings, pistons, or cylinder walls.

The rods must be checked for twist and bending, and inspected for nicks or cracks. Any issues found will necessitate the replacement of the rod.