Crankshaft Bearings Seals Fits Stihl 029 039 MS290 MS390

Two crankshaft bearings and two crankshaft seals, one of each for both sides, that fit the Stihl 029 and 039 chainsaws and the MS290, MS310 and MS390. The grooved ball bearings replace 9503-003-0440 and the seals replace 9639-003-1743. Replace them when the crankshaft has play, the engine growls with revs, or a seal weeps or has hardened. Heat the crankcase halves to fit the bearings, press the seals in square, clean the mating faces to bare metal, and pressure and vacuum test the crankcase before running the saw.

• TWO BEARINGS AND TWO SEALS, BOTH SIDES - Two grooved ball bearings, replacing 9503-003-0440, and two crankshaft seals, replacing 9639-003-1743. The same bearing and seal are used at each end.
• FITS STIHL 029 AND 039 - And the MS290, MS310 and MS390 that followed them. Compare the old parts with these before fitting.
• SIGNS THE BOTTOM END IS DUE - Play at the crankshaft when you rock it by the flywheel or clutch, a growl or rumble that rises with revs, or a seal weeping mix. A saw that lost a piston to a lean run usually had a hard seal.
• FITTING THE BEARINGS - Heat the crankcase halves to fit the bearings rather than driving them in cold, and support the crankshaft so the force goes through the inner race. Clean every mating face to bare metal before the halves go back together.
• FITTING THEM - Note which way the lip faces, pull the old seal without levering on the bearing, and press the new one in square on its outer edge. Oil the lip before the crankshaft goes through, then pressure and vacuum test the crankcase.