ENGINE DIAGNOSTIC TEST PROCEDURESSection 6Figure 14. Checking Air Cleaner Restriction400-Series On-Highway and OEM Only(Turbocharged Application Shown)*1.Air Inlet2.Turbo-Inlet3.Remote Mounted Air Cleaner4.Restriction Test Gauge (Magnehelic)5.Intake ManifoldFigure 15. Top View of Dual Element Air Cleaner1.Air Cleaner Restriction Connection2.Secondary (Inner) Element3.Air Cleaner HousingTest the restriction of the secondary (inner) element asfollows:Refer to Figure 16.1.Remove and tap the air cleaner outlet pipe (1approximately 3 inches below the air clean housing(2). Always tap in a straight section o pipe+ andclean tap thoroughly and reinstall Do not allow debristo enter air intake system+ Cover intake piping to prevent entrance of foreignmaterial into the engine.2.Attach restriction test gauge (magnahelic) (3) to aircleaner outlet pipe tap.3.Test restriction with both the primary and secondaryelements installed in the housing. Maximumallowable restriction is 6.2 kPa (2E in. H20) under fullload and rated speed for turbocharged engines.4.If maximum restriction is exceeded, remove outerelement* and recheck restriction to determine usefullife of inner element.*Primary (outer) element is serviceable. (Can becleaned). The primary element must be replaced aftersix cleanings or annually whichever occurs first.5.Secondary (inner) element is not serviceable andmust be replaced if maximum restriction is sensed.NOTE: A low air cleaner restriction reading or a lackof movement by the air cleaner restriction indicatorcould be a plugged sintered fitting. There are twodifferent types of this fitting (Figure 17). The firstfitting has a filter screen in the fitting. This screencan become plugged and not allow a correct aircleaner restriction reading to be taken. If this type offitting is found, drill center of screen with a 1/32"size drill. This fitting is welded in place and is not aserviceable part. The other type of fitting has a 0.51mm (0.020 in) orifice fitting. This type of fitting canbe easily cleaned with a fine piece of wire.Reworking the first type fitting and cleaning thesecond type fitting before running (diagnostic testswill eliminate false air cleaner restriction readings.CGES-240-4Printed in United States of AmericaPage 24
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