GM 22527479 Piston & Pinion (Std) LH(3.7993 To 3.8003In)

It is often long mileages where original pistons must be changed because of bores enlarged for normal wear and for connecting rods, although old pistons may be utilized occasionally if the cylinder walls require little more than final finishing and are still in satisfactory state. Connecting rods and pistons must be cleaned with cleaning solvent and blow with compressed air not to use wire brushes or any abrasive tool on any part of the piston. The ring grooves of the piston must be cleaned using a groove cleaner tool; where oil ring holes or slots are found and or present they must be clean. Care should be taken when inspecting the rods to ensure that they do not display signs of twist, bending, nicking or crack; in such cases they should be replaced. This covering should be checked for cracked ring lands, skirts or pin bosses, as well as worn or damaged areas and damaged pistons have to be replaced. Grooves on rings should be inspected for nicks which if present could slow the ring down. When the piston is still attached to the connecting rod, the piston should be rocked side to side to determine the degree of effort as compared between all pinston/rod assemblies; if the rods are loose on the piston pins with or with no drag, the pins are worn and should be replaced. If in any case the cylinder block requires some machine work to be done, such as finish honing, it is always best to bring the pistons to check the piston to bore clearance and this is better done in the machine shop.

Depend on whether internal or external oil filtration is to be performed, it is necessary to dismantle the oil pan, oil pump, and cylinder heads. Before pushing the piston assemblies upwards through the top of the engine block, employ the services of a ridge reamer to remove the ridge or carbon deposits at the top of the cylinder.When using the ridge reamer, work on one cylinder at a time. To resurface the piston top, start the engine and turn it to bottom the piston, put a rag over the piston to catch the cuttings and with the ridge removed, invert the engine to remove the cloth and cuttings. Check the connecting rods and caps for the cylinder numbers and put number on them, if not done, using small punch. Take out the nuts on the connecting rod stud in order and raise off the cap on the crankshaft, lay the parts side by side with each cylinder on a clean surface labeled. Apply rubber or plastic tubing on the connecting rod studs for precaution to avoid damaging the crankshaft or the cylinder wall during the disassembling of the piston assembly. Remove the piston/connecting rod assembly through the cylinder head and position the connected rod cap in the sequenced work area with referring the diagram which is given above and repeat the process for the remaining cylinder again placing the protective tubing in proper position. Pop out the small screws with which the bearing and cap and the connecting rods are connected and if the bearings are heavily used due to the many miles the engine has covered it is recommended to replace the bearings. If possible, then by the help of piston ring expanding tool, take every ring from the piston, otherwise, try to expand the ring just enough and then take the help of tin strips for taking the ring out of the piston body. Put the rings in its installed order together with the piston/connecting rod on the work area indicated with numbers. To remove the connecting rod from the piston, remove the piston pin, this can hardly be done by a mere mechanic and it is advisable to be done by the dealer or automotive machine shop who will have the appropriate tools for the job. It is better to leave the piston/rod assemblies uncleaned and un-inspected at this juncture because depending on the state of the cylinder block or crankshaft, these components may have to be replaced.

This one involves, stripping the engine including the oil pan, oil pump, and cylinder heads. Before the piston assemblies are forced up thru the top of the engine block, use the ridge reamer to remove the ridge & carbon deposits on top of each cylinder taking one cylinder at a time by turning the position of the engine such that one of the pistons sits at the bottom of a cylinder. Put a rag at the end of the connecting rod to capture the cuttings, and after clearing the ridge, turn the engine to get the piston to the top and take the cloth and cuttings away for you not to harm the piston rings, pistons, or cylinder walls. Check the connecting rods and the caps for stoke numbers and, if they are not there, then mark them with a small punch. Undo the nuts on the connecting rod stud in a synchronized manner and raise the cap on the crankshaft; the cap and bearing shall be kept on a clean surface marked to indicate the respective cylinder. It is advisable to cover the connecting rod studs with rubber or plastic tubing in order not to damage the crankshaft or the cylinder wall through the piston assembly removal. Remove the piston/connecting rod assembly through the top of the cylinder and have it sit right next to its respective rod cap at the sequenced work area for the remaining cylinders but the tubing can be used over and over. Detach the bearings by using the small screwdriver after which you will consider the state of the engine in order to reuse the connecting rods and caps or not. If available, the removal of the pistons rings from the piston is done using a piston ring expanding tool, if not available expand the ring just only to get behind the piston body and use tin strips to assist you to remove the ring. Put the rings in the order in which they are placed at the installed position after the piston/connecting rod with the number at the work area. To reduce the connecting rod from the piston, remove the piston pin; a job that must be done by a dealer or an automotive machine shop because of the tools required. Do not clean and inspect the piston/rod assemblies at this stage because its condition should dictate whether or not the cylinder block or crankshaft has to be replace.

To prepare for piston removal, mark and match each connecting rod cap to its respective connecting rod. Place rubber hose over connecting rod studs to protect the crankshaft and cylinders.

Original pistons may need replacement due to the requirement of boring the cylinders to a larger size for normal wear compensation. However, if the cylinder walls only need slight finish honing, old pistons may be reused if they are in good condition.

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.