Spark Plugs - Toro 73546 Wheel Horse 520Lxi Operator's Manual

Spark Plugs

Service Interval/Specification
Check the spark plugs and reset the air gap as
necessary. Replace the spark plugs after every 100
operating hours. Make sure the air gap between the
center and side electrodes is correct before installing
the spark plugs. Use a spark plug wrench for
removing and installing the spark plugs and a
gapping tool/feeler gauge to check and adjust the air
gap.
Type: NGK BMR4A
Air Gap: 0.024–0.028" (0.6–0.7 mm)
Removing the Spark Plugs
1. Disengage the power take off (PTO), set the
parking brake, lower the attachment lift, and turn
the ignition key to "STOP" to stop the engine.
Remove the key.
2. Open the hood.
3. Pull the wire(s) off the spark plug(s) (Fig. 30).
Now clean around the spark plug(s) to prevent
dirt from falling into the engine and potentially
causing damage.
4. Remove the spark plug(s) and metal washer.
1
Figure 30
1. Spark plug wire
2
m–3428
2. Spark plug
Checking the Spark Plugs
1. Look at the center of the spark plug(s) (Fig. 31).
If you see light brown or gray on the insulator,
the engine is operating properly. A black coating
on the insulator usually means the air cleaner is
dirty.
IMPORTANT: Never clean the spark plug(s).
Always replace the spark plug(s) when it has:
a black coating, worn electrodes, an oily film,
or cracks.
2. Check the gap between the center and side
electrodes (Fig. 31). Bend the side electrode
(Fig. 31) if the gap is not correct.
2
1
Figure 31
1. Center electrode insulator
2. Side electrode
Installing the Spark Plug
1. Install the spark plug(s) and metal washer. Make
sure the air gap is set correctly.
2. Tighten the spark plug(s) to 17 ft-lb (23 Nm).
3. Push the wire(s) onto the spark plug(s) (Fig. 30).
4. Close the hood.
Maintenance
3
m–3215
3. Air gap (not to scale)
(s)
29