Cub Cadet MTD 70 Series - Manual (Page 93)

Ignition System
87
Flywheel
The flywheel holds the magnets that induce a field in the module which in turn produces a spark. But it also con-
trols the timing of the ignition system by controlling when the magnets are introduced to the module.
A sheared flywheel key will throw off the ignition timing. They are uncommon on the MTD engine. If one is found,
check for a bent crankshaft.
To Remove and/or inspect the flywheel and key:
1. 1.Remove the recoil assembly by following the steps
describe in Chapter 6: Starter and Charging System.
2. Remove the blower housing.
3. Loosen the flywheel nut until it is a couple of threads
past the end of the crankshaft using a 19mm wrench.
4. Remove the flywheel by applying a sharp blow to the
crankshaft using a brass drift punch and a hammer
while gently prying with a prybar. The flywheel will
loosen then lift it off.
NOTE: Never strike the crankshaft directly with a hammer.
To prevent damage to the crankshaft use a brass
drift punch or a piece of wood between the ham-
mer and the crankshaft. See Figure 7.15.
5. Inspect the key, keyway, and tapered mating sur-
faces of the flywheel and crankshaft.
NOTE: If the key is damaged it must be replaced. If
there is damage to the crankshaft, the
engine must be short blocked because the
crankshaft is not available as a service part.
NOTE: On installation, confirm that the key is prop-
erly seated (the flat of the key parallel with
the threaded section of the crankshaft) in the
keyway, and that the tapers are fully seated.
Key or keyway failure may result from
improper seating.
IMPORTANT: The tapers in flywheel and on the
crankshaft must be clean and dry.
The flywheel is held in place by the
friction between the flywheel and the
crankshaft, not the key. The key is
only to guide the flywheel to the proper position until it is torqued down.
6. Install the flywheel nut to a torque of 47 - 52 ft lbs (64-70 Nm).
7. Adjust the air gap by following the steps described in the previous section of this chapter.
8. Reassemble the engine.
9. Test run the engine before returning to service.
Figure 7.13
Brass punch
! CAUTION ! CAUTION
If the flywheel shows any signs of physical damage such as cracks, broken vanes (if
equipped), or a damaged keyway, replace it. A damaged flywheel poses a threat of a burst
failure. Burst failures are extremely hazardous to surrounding people and property.
Figure 7.14
Key flat parallel to the threads
Taper