Remove the mudguards from under the engine.
If present, disconnect the hoses attached to the crankcase and move them to the side.
Where installed, disconnect the electrical connector from the oil level sensor.
Where present, remove the inspection hole cover located at the rear of the oil pan.
Remove the bolts securing the oil pan to the engine block and front/rear covers.
Gently tap the crankcase with a mallet and remove it from the engine.
Using a scraper, clean all traces of old sealant from the engine block, timing chain cover, rear oil seal housing and crankcase. Be especially careful not to damage the surfaces.
Clean the oil pan with solvent and dry it thoroughly. Make sure that the contact surfaces are not deformed and wipe them with a rag soaked in solvent.
Before installing the crankcase, apply a small amount of sealant to the area where the front and rear covers meet the cylinder block. Place a new oil pan gasket on the engine block. If necessary, apply more sealant to hold the gasket in place.
Carefully install the crankcase, being careful not to dislodge the gasket, and screw in the bolts. Start with the bolts located in the center of the crankcase and, moving in a diagonal sequence, tighten the bolts to the required tightening torque.
Next, install in the reverse order of removal.
Finally, fill the engine with oil. Start the engine and check the joints for leaks.