Toro 500 EFI Service Manual page 38

Problem: Engine noisy (Noise seems to come from secondary bevel gear and final driven shaft)
Condition
1. Drive - driven bevel gears damaged - worn
2. Backlash excessive
3. Tooth contact improper
4. Bearing damaged
5. Gears worn - chipped
6. Splines worn
7. Final driven shaft thrust clearance too large
Problem: Engine idles poorly
Condition
1. Valve clearance out of adjustment
2. Valve seating poor
3. Valve guides defective
4. Rocker arms - arm shaft worn
5. Magneto defective
6. ECM defective
7. Spark plug fouled - gap too wide
8. Ignition coil defective
9. Fuel injector obstructed
Problem: Engine runs poorly at high speed
Condition
1. High RPM "cut out" against RPM limiter
2. Valve springs weak
3. Valve timing out of adjustment
4. Cams - rocker arms worn
5. Spark plug gap too narrow
6. Ignition coil defective
7. Air cleaner element obstructed
8. Fuel hose obstructed
Problem: Exhaust smoke dirty or heavy
Condition
1. Engine oil overfilled - contaminated
2. Piston rings - cylinder worn
3. Valve guides worn
4. Cylinder wall scored - scuffed
5. Valve stems worn
6. Stem seals defective
Problem: Engine lacks power
Condition
1. Valve clearance incorrect
2. Valve springs weak
3. Valve timing out of adjustment
4. Piston ring(s) - cylinder worn
5. Valve seating poor
6. Spark plug fouled
7. Rocker arms - shafts worn
8. Spark plug gap incorrect
9. Fuel injector obstructed
10. Air cleaner element obstructed
11. Engine oil overfilled - contaminated
12. Intake manifold leaking air
13. Cam chain worn
Problem: Engine overheats
Condition
1. Carbon deposit (piston crown) excessive
2. Oil low
3. Octane low - gasoline poor
4. Oil pump defective
5. Oil circuit obstructed
6. Intake manifold leaking air
7. Coolant level low
8. Fan malfunctioning
9. Fan relay malfunctioning
10. Thermostat stuck - closed
11. Radiator hoses - cap damaged - obstructed
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Remedy
1. Replace gears
2. Adjust backlash
3. Adjust contact
4. Replace bearing
5. Replace gears
6. Replace shaft(s) - gears
7. Replace thrust washer(s)
Remedy
1. Adjust clearance
2. Replace - service seats - valves
3. Replace guides
4. Replace arms - shafts
5. Replace stator coil
6. Replace ECM
7. Adjust gap - replace plug
8. Replace ignition coil
9. Replace fuel injector
Remedy
1. Shift into higher gear - decrease speed
2. Replace springs
3. Adjust timing
4. Replace cams - arms
5. Adjust gap
6. Replace ignition oil
7. Clean element
8. Clean - prime hose
Remedy
1. Drain excess oil - change oil
2. Replace cylinder - service rings
3. Replace guides
4. Replace cylinder
5. Replace valves
6. Replace seals
Remedy
1. Adjust clearance
2. Replace springs
3. Time camshaft
4. Replace cylinder - service rings
5. Repair seats
6. Clean - replace plug
7. Replace arms - shafts
8. Adjust gap - replace plug
9. Replace fuel injector
10. Clean element
11. Drain excess oil - change oil
12. Tighten - replace manifold
13. Replace cam chain - sprockets
Remedy
1. Clean piston
2. Add oil
3. Drain - replace gasoline
4. Replace pump
5. Clean circuit
6. Tighten - replace manifold
7. Fill - examine system for leaks
8. Check fan fuse/fan relay - replace fan
9. Replace fan relay
10. Replace thermostat
11. Clear obstruction - replace hoses