Toro 303447 Troubleshooting Manual

COMPRESSION ‐‐ This is necessary for the engine to reachits maximum efficiency.Loss can be due to a leak occurring from the valves, ringsor cylinder head.This can be checked by spinning the flywheel counter‐clockwise. If the compression is adequate the flywheelshould rebound sharply.Or perform a compression testA compression test checks the air pressure built up in thecylinder as the piston comes up, and the air iscompressed.This test will gauge the condition of the intake andexhaust valves, piston rings and cylinder walls, and headgaskets or other sealing components,Preparing the unit for the testRemove all the Sparkplug(s).Connect Battery Charger if equipped with electric start)On single cylinder engine, with compression release,engine may need to be rotated backwards. Refer to theengine manufactures documentations.Crank engine a consistent number of compressionstrokes.Note the compression pressure.On multiple cylinder engines, the actual compressionreading is not as important at the relationship between allcylinders.NOTE: There are too many factors that can result in allcylinders reading low.