What do I need to adjust the valve lash on a lawn mower?
An inexpensive tool called a Feeler gauge is needed to set the valve lash. Each engine manufacturer will have a different spec for their engines, intake and exhaust measurements will sometimes differ also. Check your valve lash spec with your engine maker.
When do you remove the valve springs on a L-head engine?
To correctly adjust the valves, the valve springs must be removed (L-head engines only) and have the piston at 1/4″ past TDC on the power stroke.
What are the symptoms of a valve gap on a lawn mower?
As an engine wears, this valve lash (gap) gets larger and needs to be checked and adjusted. Symptoms include: Starter cord hard to pull. Hard starting. Lack of power. Rough running. Oil leaks. Noisy engine.
What does the compression valve do on a riding lawn mower?
Most mowers will have a compression release mechanism, its job is to open the valves a little early, releasing cylinder pressure. This makes pulling the starter cord less physically demanding. When the engine hits 350 rpm, the plug fires and the engine starts, the release mechanism is then deactivated by a centrifugal flyweight.
Do you need a feeler gauge to adjust a valve lash?
An engine equipped with a hydraulic cam does not require a feeler gauge. When adjusting the valve lash on an engine with hydraulic lifters, you are not really setting the lash or clearance. You’re actually setting the preload on the lifter through the pushrod and rocker arm.
How is the valve lash on a hydraulic lifter set?
When adjusting the valve lash on an engine with hydraulic lifters, you are not really setting the lash or clearance. You’re actually setting the preload on the lifter through the pushrod and rocker arm. The traditional adjustment on a hydraulic lifter is zero lash.
How many shims do you need to change gear tooth Lash?
Note: When adjusting for gear tooth lash by installing or removing shims, the same number of shims must be changed under each foot so that the pump will always be level on the engine block. The insertion or removal of one 0.127 mm (0.005 in.) shim will change the gear tooth lash by approximately 0.102 mm (0.004 in.).