The flywheel key is a rectangular metal peg that keeps the crankshaft and flywheel aligned when you tighten the flywheel nut. If the mower blade hits an object with enough force to knock the flywheel out of alignment, the flywheel key breaks, protecting expensive parts such as the crankshaft from damage.
Why is my riding lawn mower revving high?
Airflow Issues
A lawnmower that hunts and surges may be experiencing something as simple as an airflow issue. If the air that the engine requires to run is blocked, especially sporadically, it can cause the engine to slow down. When the blockage moves or clears, the engine may suddenly rev up in response.
How do I know if my riding lawn mower is locked up?
Following are the signs that your lawn mower engine is seized.
Engine sounds rough.Engine does not start.Blades do not move and are stuck.The cylinder and piston are fixed.Low oil level.Deteriorated fuel quality.
How do I remove a sheared Woodruff key?
Remove the Woodruff key.
Try tapping down on one end of the key with a hammer and nail. Rapidly heating the key with a blowtorch and letting it cool can help loosen it.Remember that these keys are cheap and readily available online or at hardware and auto part stores, so causing damage to it may be necessary.
How do you keep a Woodruff key in place?
To keep a woodruff key in place while installing a mating component, ensure that it is situated tightly in the key seat. Since woodruff keys are made to tight tolerances, they often require a press fit into their seat.
What holds the flywheel in place?
Virtually every flywheel or rotor is attached to the crankshaft by a taper on the crank, which matches the flywheel. Torque from the fixing bolt holds the flywheel securely on the shaft.
Can a small engine loose timing?
The timing can become off a number of ways. Most often it is a result of use and wear as the tight fit of all the mechanical components wear and loosen up. Many small engines have timing belts that can slip or break.
Do lawn mowers have shear pins?
Most lawn mowers use Briggs and Stratton engines–low-horsepower engines with easily-replaceable parts. Most likely you will have to replace the shear pin.
What is a shear pin on a lawn mower?
The flywheel key (sometimes called a shear pin) is a rectangular piece of soft metal that keeps the flywheel in alignment with the crankshaft. The key shears if the mower blade strikes something immovable, such as a tree root or large rock. That shear is by design so the engine does not suffer extensive damage.
What causes a lawn mower engine to lope?
The most common reason for a surging lawn mower engine is a blockage in the fuel supply, but there are other possibilities: Bad gas. Bad spark plug. Dirty / faulty carburetor.
Why is my lawn mower not running smoothly?
A dirty air filter is one of the most common causes of a poorly running lawn mower, since it starves the engine of the oxygen needed for combustion. Fuel Filter: Check the fuel filter on the mower to make sure it’s clean, and replace it if needed.
