Toro 303447 - Troubleshooting: Compression; Checking Engine Compression; Compression Test Procedures

COMPRESSION‐‐Thisisnecessaryfortheenginetoreach
itsmaximumefficiency.
Losscanbeduetoaleakoccurringfromthevalves,rings
orcylinderhead.
Thiscanbecheckedbyspinningtheflywheelcounter‐
clockwise.Ifthecompressionisadequatetheflywheel
shouldreboundsharply.
Orperformacompressiontest
Acompressiontestcheckstheairpressurebuiltupinthe
cylinderasthepistoncomesup,andtheairis
compressed.
Thistestwillgaugetheconditionoftheintakeand
exhaustvalves,pistonringsandcylinderwalls,andhead
gasketsorothersealingcomponents,
Preparingtheunitforthetest
Remove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the
enginemanufacturesdocumentations.
Crankengineaconsistentnumberofcompression
strok es.
Notethecompressionpressure.
Onmultiplecylinderengines,theactualcompression
readingisnotasimportantattherelationshipbetweenall
cylinders.
NOTE:Therearetoomanyfactorsthatcanresultinall
cylindersreadinglow.