Before adjusting the size of the gap to adjust the crankshaft pulley, it is necessary to decommission the drivebelt. Secondly, take out the crankshaft pulley bolt. Thread a longer shorter diameter bolt into the crankshaft to act as a stop for the puller then use a puller for this purpose to remove the crankshaft pulley. Do not try to pry the pulley off or use perchance a impact puller. Coat with clean engine oil the interface contact surface of the pulley that engages the front seal before fitting the crankshaft pulley to the crankshaft without hammering, then, tighten the pulley bolt to the recommended torque. To replace front oil seal, first, remove the crankshaft pulley, the oil seal then is removed by prying it out with a screwdriver being cautious not to damage the cover in the process. Scrub the seal bore and check for roughness or injuries on it with sharp edges or scratches. Apply clean engine oil to the lip of the new seal and insert it into the bore with a socket or a piece of pipe which is slightly smaller in diameter than the seal with the open side of the seal pointing towards the engine. Last of all, the crankshaft pulley ought to be repositioned back.