Oil Pump Piston Replacement For Stihl Ms 461 Chainsaw

You need a STIHL tool with a 19mm box end and a T27 torx bit on the long shaft end. You will need a small 1/4 wide slotted screwdriver. You will also need a piston blocking tool of some sort, or you can just rotate the piston to bottom dead center and jam a length of pull cord into the plug hole leaving enough of a tail to pull it out with again, and rotate the piston up against it. First you need to remove the two nuts securing the clutch cover to the guide bar with the 19mm end. Remove the cover to access the guide bar and cutting chain and remove both. You will see an e-clip securing a washer to the top of the sprocket and clutch drum. Use the screwdriver to remove the e-clip being careful not to let it fire off into outerspace, as it has spring-like properties when being removed and may fling out of sight. I would try to put the screwdriver in one of the two slots and twist it against the end of the crankshaft to force the clip off. To install it, slide it back into the groove it came from, and push it squarely from behind with the screwdriver until it fully clicks into the groove. Once you remove the clip, the washer, sprocket, clutch drum, and clutch drm bearing all slide up and off the shaft. Note the order of parts for aid with reassembly. Next, rotate the clutch in a clockwise direction until the piston compresses against the rope or piston blocking tool, and with the 19mm box end, continue to rotate the clutch in the same direction until the clutch gives way. Spin the clutch off and you will see a flat washer, (note which side is facing you,) the worm gear which shoulg just pop up with the screwdriver with minimal force, and the oiler behind it held in by two T27 screws. Use the other end of the STIHL tool with the T27 bit to remove them, and the oiler will simply pull off and out of the pickup hose. The installation is the reverse of removal. make sure all bolts and nuts are tight, and that all bearings and rotating parts spin "freely" without any binding or stiction. Reinstall the plug and the oiler should work. PS, don't forget to add oil to the oil tank!