Exmark NAVIGATOR NV640KC Operator's Manual page 40

Troubleshooting
Problem
Engine loses power.
Engine overheats.
Mower pulls left or right (with levers fully
forward).
Machine does not drive.
Abnormal vibration.
Possible Cause
1. Engine load is excessive.
2. Air cleaner is dirty.
3. Oil level in the crankcase is low.
4. Cooling fins and air passages for the
engine are plugged.
5. Vent hole in the fuel cap is plugged.
6. Dirt in fuel filter.
7. Dirt, water, or stale fuel is in the fuel
system.
1. Engine load is excessive.
2. Oil level in the crankcase is low.
3. Cooling fins and air passages for the
engine are plugged.
1. Tracking needs adjustment.
2. Tire pressure in drive tires not correct.
3. Reverse indicator and speed control
linkage need adjustment.
1. Bypass valve is not closed tight.
2. Drive or pump belt is worn, loose or
broken.
3. Drive or pump belt is off a pulley.
4. Broken or missing idler spring.
5. Hydraulic fluid level is low or too hot.
1. Engine mounting bolts are loose.
2. Loose engine pulley, idler pulley, or blade
pulley.
3. Engine pulley is damaged.
4. Belt is damaged.
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Corrective Action
1. Reduce the ground speed.
2. Clean or replace the air cleaner element.
3. Add oil to the crankcase.
4. Remove the obstructions from the cooling
fins and air passages.
5. Clean or replace the fuel cap.
6. Replace the fuel filter.
7. Contact an Authorized Service Dealer.
1. Reduce the ground speed.
2. Add oil to the crankcase.
3. Remove the obstructions from the cooling
fins and air passages.
1. Adjust the tracking.
2. Adjust tire pressure in the drive tires.
3. Adjust the reverse indicator and the speed
control linkage.
1. Tighten the bypass valve.
2. Change the belt.
3. Change the belt.
4. Replace the spring.
5. Add hydraulic fluid to reservoir or let it
cool down.
1. Tighten the engine mounting bolts.
2. Tighten the appropriate pulley.
3. Contact an Authorized Service Dealer.
4. Install new belt.