my 455 rancher chain saw is not using her chain oil

Replace the oil pump..Or just try to clean it out but I have been through this and it worked for about ten minutes and I ended up just replacing the pump and works fine now. They are not very expensive (35.00-40.00) and only takes about ten minutes. Get a beer and a table or the tail gate of you truck should be fine. Take off the side cover remove the bar and chain. Clean everything up... air compressor is best a paint brush and rag works good if you do not have a air compressor. Take the top plastic cover (three screws on top of the saw). Pull the spark plug and feed a piece of rope into the cylinder. This will bind up saw so you can remove the clutch. I use a pull start rope from my old lawn mower and keep it in my saw box for this reason. This size and kind of rope seems to work best. Now you need to remove the clutch. There is an arrow on the clutch that tells you which way to turn it to get it off. This can sometimes be tricky but don't give up. I'm sure there is a tool for this and I keep saying that I'm going to make something. I use the handle of a good strong pair of pliers and turn the plier with a pair of vice grips. When you see the clutch you'll figure out something to use to loosen it and spin it off. Un-spin the clutch and remove the clutch drum by just sliding it off the spindle. Be careful because there is a bushing with needle bearings. The bearings are in there pretty good and wont just fall out. If you want to replace that you can 14.00 or so. There is also a plastic drive gear for the pump that just lifts out , replace it too 6.00 or so. Take off the metal cover I think it's just one screw. When you remove the cover you may see a lot of saw dust and oil all packed inside. If you have an air compressor just blow it all out. The oil pump is right there and is simply removed with one screw. clean every thing up put the new pump in put everything back together and you should be back in business.

The pump is behind the clutch and sprocket the clutch is a LH thread the nylon pump gear is prone to strip due to debri in gears...