Official McCulloch lawn & garden engine parts

Common replacement parts for McCulloch lawn and garden equipment engines

• Spark plug. A spark plug is the device responsible for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine. This current ignites the compressed fuel/air mixture by means of an electric spark, while containing combustion pressure within the engine.
• Air filter. The air filter prevents abrasive particles from entering the engine's cylinders, which could cause mechanical wear and oil contamination.
• Fuel filter. A fuel filter is a filter in the fuel line that screens out dirt and rust particles from the fuel. The fuel filter paper is usually integrated into a cartridge. Fuel filters used with in most internal combustion engines.
• Oil filter. An oil filter is a filter designed to remove contaminants from engine oil, transmission oil, lubricating oil or hydraulic oil.
• Flywheel key. The flywheel key is a small metal rectangle that keeps the crankshaft and flywheel aligned when you tighten the flywheel nut. To protect more expensive components from damage, the flywheel key is designed to shear if the mower blade hits an object hard enough to make the flywheel slip out of alignment with the crankshaft.

Checking compression on a McCulloch lawn and garden equipment engine

Connect the compression gauge to the cylinder through the spark plug hole. Zero the compression gauge. Briefly turn the key to the start position so the starter motor spins the engine or pull the starter rope to spin the engine.

Check the compression reading. Most engines should measure over 40 psi of compression. Many engines produce more than 80 psi.

If cylinder compression is less than 40 psi, the piston isn't compressing air inside the cylinder. Keep in mind that a low compression reading shows you that a compression problem exists, but doesn't reveal the cause. You might need to adjust the valves or replace the piston rings. A damaged cylinder wall can also prevent the piston from compressing air inside the cylinder.

To accurately analyze a compression problem, have a service technician do a leak-down test on the engine. The technician will use an air compressor and special tools to find where the air leaks. Once the technician finds the cause of the compression problem and fixes it, you can get back to performing your lawn and garden chores.