The job of the piston ring is to provide a seal between the piston and the cylinder wall, which allows for compression. The piston ring also helps to keep oil out of the combustion chamber. When these rings become worn, oil can enter the combustion chamber, and the burning oil can create black smoke. Worn or damaged piston rings will need to be replaced, or it can cause further problems for your lawn tractor. A compression test will tell you if you have low compression, and this indicates that the rings are bad. After you have determined the rings are bad, start by removing the hood and draining all fluids. Remove the air filter, then the blower housing and oil drain tube from the blower housing. Remove wires from starter and disconnect the spark plug wire and spark plug. Next, remove the exhaust manifold and the carburetor from the cylinder...
The job of the piston ring is to provide a seal between the piston and the cylinder wall, which allows for compression. The piston ring also helps to keep oil out of the combustion chamber. When these rings become worn, oil can enter the combustion chamber, and the burning oil can create black smoke. Worn or damaged piston rings will need to be replaced, or it can cause further problems for your lawn tractor. A compression test will tell you if you have low compression, and this indicates that the rings are bad. After you have determined the rings are bad, start by removing the hood and draining all fluids. Remove the air filter, then the blower housing and oil drain tube from the blower housing. Remove wires from starter and disconnect the spark plug wire and spark plug. Next, remove the exhaust manifold and the carburetor from the cylinder head. Remove the engine mounts, disconnect the engine, and place it on a work bench. With the engine on a stable work surface, pull the valve cover off and rotate the piston to the bottom. Remove the rocker arm nuts and push rods, then unscrew all the bolts holding the cylinder head to the engine block and remove the head. Pull off the old head gasket. Clean both the surfaces of the engine block and the cylinder head with a soft brush. Be careful not to damage this area, or you will not be able to achieve a tight seal.
Next, remove the crankcase bolts and wiggle it off. You may have to tap it off lightly with a hammer and punch wherever you can make contact on the case. There may even be a key way on the crankshaft that will have to be removed as well, depending on your specific model. Next, remove the camshaft by simply pulling it out. Then, remove the camshaft tappets, the connecting rod bolts, and the bottom part of the rod bearing. Rotate the crankshaft to the top then reach in and push the piston out with your fingers. Clean any parts that you intend to re-use with parts cleaner and dry them thoroughly. Install new rings on the piston and make sure the oil ring is on the bottom. Using a piston ring installer, gently tap the piston into the cylinder, making sure to lubricate the cylinder with fresh motor oil beforehand. It’s worth nothing that all bots must be torqued to the manufacturer’s specifications. With the piston at top dead center, and touching the crankshaft, rotate both together by pushing down on the piston so you can re-attach the connecting rod bearing. Lubricate the camshaft tappets and re-install, then install the camshaft by making sure the timing marks are in line. Be sure to lubricate all moving parts with motor oil or white grease first. Re-install the cover with a new gasket then re-install the cylinder head with a new gasket. Install the connecting rods and bolts, as well as the cover with a new gasket. Finally, re-attach the carburetor, muffler, fuel pump, fan, and engine cover.
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