The oil pump on Stihl chain saws feeds the bar with oil while cutting. For the bars to get oil on Stihl saws, the engine has to be turning the clutch at a certain speed because the oil pump is connected to the clutch. When the oil pump isn't working correctly the bar will not have proper lubrication, which can cause excessive friction on the tip and in the engine. Proper chain lubrication is essential to maximise the performance of your Stihl chain saw.
Make sure the adjustable oiler is properly adjusted. The adjustable oiler is located on the bottom of the saw, and is a picture with a plus and minus sign with a little oil can next to it.
Increase the oil volume by turning the screw counterclockwise. Start the saw and hold the bar's tip about an inch away from a piece of wood. Depress the throttle and look for a little splattering of bar oil against the wood.
Use the wrench to loosen the clutch cover's bolts. Use the screwdriver to release the bar tensioner screw. Remove the bolts and the clutch cover. Take off the bar and remove the chain from the bar.
Remove the oil plate cover with the screwdriver. Use the sharp corner of the oil plate to clean out the bar's guide slot. Insert the oil plate at the top of the bar and scrape down the length of the bar. Repeat this until the oil plate slides smoothly down both sides of the bar, and the guide slots are free of oil, dirt and sawdust.
Pull the spark plug's connecting rubber plug and insert enough of the starter cord into the open shaft to block the piston from moving. This will allow you to remove the clutch assembly and investigate the problem on the saw's oil pump.
Remove the E-clip from the sprocket with the screwdriver. Pull off the E-clip, washer and sprocket. Remove the clutch drum as well.
Remove clutch with clutch removal tool. The clutches on Stihl saws are left-hand locking; to loosen, turn the bolt clockwise to take off clutch. Remove the chain brake band, above the clutch, by unscrewing it with the screwdriver.
Unscrew oil pump mounting screws, which are located underneath the clutch assembly. Pull the pump off of the crankshaft by gently sliding it out.
Unscrew the pump's adjustment screws with the screwdriver to disassemble the oil pump. Take apart the worm, drive spring, plug and plunger from the pump's housing. Clean all the parts with gasoline, wire brush and rag. Keep any parts that aren't damaged or broken. Replace broken or damaged parts with new ones.
Reassemble the old oil pump or use the new oil pump kit if most of the parts need to be replaced. Use engine lubrication to grease the worm drive, spring and its plug.
Reconnect the saw's parts following these steps in reverse order.
If there is excessive build-up and dirt on the oil pump, you can soak the parts over night in carburettor cleaner. Check the oil lines, oil tank, oil filter and oil tank vent if the problem persists.