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GeneralInformationENGINE–SUBARUEX40
524
Figure20-4SparkPlug
TestingtheSparkPlug
Checkthesparkingabilityofacleanedandproperlygappedplugonasparkingcomparatorifpossible.Sparkshould
beblueandstrongandabletojumpa5/16-in.(8mm)gap.
SettingtheSparkGap
1.Passacontactpointlebetweentheelectrodestoproduceat,parallelsurfacestofacilitateaccurategauging.
2.Useawiretypegauge.Bendtheoutsideorgroundelectrodesoonlyaslightdragonthegaugeisfeltwhen
passingitbetweentheelectrode.Nevermakeanadjustmentbybendingthecenterelectrode.Setgap(A)from
0.024to0.028in.(0.6to0.7mm)(Figure20-4,Page20-6).
SparkPlugInstallation
NOTE:Beforeinstallingtheplug,checktheconditionofthethreadsinthecylinderhead.Softendepositsincylinder
headthreadswithpenetratingoilandcleanthethreadswithatapifnecessary.
Useahightemperature,anti-seizelubricantonthethreadsofthesparkplugtoreducefrictionwheninstalling
anewplug,andreduce“gauling”andthreadseizingforfuturereplacements.
Installthesparkplugbythreadingitinuntilngertight,thentightenthesparkplugtothefollowingtorque:
•New:120lb·in(13.5N·m).
•Re-tightening:216lb·in(24.5N·m).
BREATHER
Thefunctionofthebreatheristocreateavacuuminthecrankcasewhichpreventsoilfrombeingforcedoutofthe
enginethroughthepistonrings,oilsealsorgaskets.Thebreatherhasareedvalvewhichlimitsthedirectionofairow
causedbythepistonmovingupanddown.Aircanowoutofthecrankcase,buttheone-wayreedvalveblocksreturn
owandthereforemaintainsavacuuminthecrankcase.
Oilladenairinthecrankcasepassesthroughthereedvalveandexpandsintotherockercamber.Intherocker
cambermostoilseparatesfromtheairanddrainsbacktothecrankcase.Theairpassesthroughatubeandventsto
theintakemanifold.
Page20-62018OnwardMaintenanceandServiceManual
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