2004 John Deer Buck Utility ATV 500, 500EX and 500EXT Service Manual, Page 35Get this manual
Check oil strainer on engine bottomScrew(s) is (are) loose andor gasket is damaged, brittle or hard? Oil strainer is clogged due to contamination? Retighten screw andor replace gasketClean or replace strainer and diagnose causesReplace possible damaged partsUse high quality oil (refer to Specifications" section)Go to next stepCheck leak indicator hole for oil leaks (water pump housing area MAG side)Oil leaking from leak indicator hole means damaged oil seal inside magneto cover on water pump shaftReplace both rotary seal and oil seal (refer to "Cooling System" and "Magneto System") Go to next stepCheck oil pressure switch functionOil pressure switch damaged? Replace oil pressure switchGo to next stepCheck oil orifice(s) on the oil pump suction sideOil orifice(s) is (are) clogged? Clean from contaminationReplace oil and oil filter if necessary (refer to "Maintenance" or "Lubrication")Go to next stepCheck oil pump operationOil pump rotor is out of wear limit? Replace oil pump shaft (refer to "Lubrication")Go to next stepOil pump seized due to oil leakage andor air inclusion? Replace oil pump (refer to "Lubrication")Go to next stepGears driving oil pump are broken or damaged? Replace gearsGo to next stepCheck plain bearings in crankcase for heavy wearPlain bearings out of specification (increased clearance)? Replace all plain bearings at the same time (refer to "Crankshaft")Go to next step Piston rings worn out (blue-colored engine exhaust emission)? Replace piston rings (refer to "Cylinder and Head")Go to next stepPiston rings are broken (low compression and bluecolored engine exhaust emission)? Replace piston rings (refer to "Cylinder and Head")Go to next stepValve stem seal damaged andor sealing lip is hard andor brittle? Replace all valve stem seals