DETERMINING ENGINE CONDITION. COMBUSTION CHAMBER EFFICIENCY B AFFECTED BY: AIR/FUEL MOVEMENTAIR/FUEL MOVEMENT COMBUSTION TURBULENCECOMBUSTION TURBULENCE.

DETERMININGDETERMININGENGINE ENGINE

CONDITIONCONDITION

COMBUSTION CHAMBER COMBUSTION CHAMBER EFFICIENCY EFFICIENCY

AFFECTED BY:AFFECTED BY:• AIR/FUEL MOVEMENTAIR/FUEL MOVEMENT• COMBUSTION TURBULENCECOMBUSTION TURBULENCE• INTAKE DESIGNINTAKE DESIGN• EGREGR• COMBUSTION CHAMBER DESIGNCOMBUSTION CHAMBER DESIGN

MANUAL COMPRESSION MANUAL COMPRESSION TESTING (CYL. SEALING)TESTING (CYL. SEALING)

EASIEST MANUAL TEST IS A VACUUM EASIEST MANUAL TEST IS A VACUUM TESTTEST

EACH CYLINDER IS A INDIVIDUAL AIR EACH CYLINDER IS A INDIVIDUAL AIR PUMPPUMP

THERE MUST BE A GOOD CYLINDER THERE MUST BE A GOOD CYLINDER SEAL TO HAVE GOOD VACUUMSEAL TO HAVE GOOD VACUUM

ANY CYLINDER LEAK WILL SHOW ON ANY CYLINDER LEAK WILL SHOW ON VACUUM GAUGEVACUUM GAUGE

VACUUMVACUUM

Measured in Inches of Mercury (Hg)Measured in Inches of Mercury (Hg) A Reduction of 1 inch of vacuum A Reduction of 1 inch of vacuum

per 1000 feet increase in altitudeper 1000 feet increase in altitude Pounds Per Square Inch Absolute Pounds Per Square Inch Absolute

(PSIA) (PSIA) Air moves rapidly from a High Air moves rapidly from a High

pressure to a low pressurepressure to a low pressure

C24-25

VACUUM TESTING VACUUM TESTING PROCEDURESPROCEDURES

CRANKING VACUUMCRANKING VACUUM IDLE VACUUMIDLE VACUUM IDLE THROTTLE ANGLE CHECKIDLE THROTTLE ANGLE CHECK 2500 RPM VACUUM2500 RPM VACUUM PISTON RING TESTPISTON RING TEST IDLE/DRIVE TESTIDLE/DRIVE TEST CRUISE TESTCRUISE TEST VAC AT W.O.T. AND AFTER W.O.T.VAC AT W.O.T. AND AFTER W.O.T.

L138

TYPICAL VACUUM TYPICAL VACUUM READINGSREADINGS

CRANKING VACUUM 3-5”CRANKING VACUUM 3-5” IDLE VACUUM 18”IDLE VACUUM 18” IDLE THROTTLE ANGLE 0”IDLE THROTTLE ANGLE 0” 2500 RPM VACUUM 20”2500 RPM VACUUM 20” VAC TEST PROCEDURE CAN VAC TEST PROCEDURE CAN

IDENTIFY POTENTIAL PROBLEMSIDENTIFY POTENTIAL PROBLEMS COMPRESSION TEST CAN PINPOINTCOMPRESSION TEST CAN PINPOINT

COMPRESSION TESTINGCOMPRESSION TESTING

READING COMPRESSION READING COMPRESSION GAUGEGAUGE

1ST PUFF - SHOULD BE 50% OF 1ST PUFF - SHOULD BE 50% OF FINAL PUFF (INDICATOR OF FINAL PUFF (INDICATOR OF CYLINDER WALL AND RINGS)CYLINDER WALL AND RINGS)

ALL READINGS UNIFORMALL READINGS UNIFORM IF REAL HIGH - CARBON BUILD-UPIF REAL HIGH - CARBON BUILD-UP IF CHANGE ON ONE CYL - IF CHANGE ON ONE CYL -

POSSIBLE STICKING VALVEPOSSIBLE STICKING VALVE

COMPRESSION AND VACUUMCOMPRESSION AND VACUUM BOTH REQUIRE GOOD CYLINDER SEALBOTH REQUIRE GOOD CYLINDER SEAL LACK OF CYLINDER SEAL WILL LACK OF CYLINDER SEAL WILL

PREVENT PRESSURE TO RISE HIGH PREVENT PRESSURE TO RISE HIGH ENOUGH TO IGNITE THE MIXTUREENOUGH TO IGNITE THE MIXTURE

COMPRESSION & VAC TEST INDICATES COMPRESSION & VAC TEST INDICATES CYLINDER SEAL, RUNNING CYLINDER SEAL, RUNNING COMPRESSION TEST INDICATES COMPRESSION TEST INDICATES VOLUMETRIC EFFICIENCYVOLUMETRIC EFFICIENCY

CYLINDER BALANCECYLINDER BALANCE

MANUAL CYLINDER MANUAL CYLINDER BALANCEBALANCE

SHORTING PLUG ONE BY ONESHORTING PLUG ONE BY ONE TIME CONSUMINGTIME CONSUMING DON’T OPEN CIRCUIT SECONDARY DON’T OPEN CIRCUIT SECONDARY

CIRCUITCIRCUIT WILL PINPOINT LOW POWER WILL PINPOINT LOW POWER

OUTPUT OF A CYLINDEROUTPUT OF A CYLINDER

OTHER CYLINDER OTHER CYLINDER BALANCE TESTSBALANCE TESTS

ELECTRONICALLY PERFORMED BY ELECTRONICALLY PERFORMED BY ENGINE ANALYZERENGINE ANALYZER• CRANKING TESTCRANKING TEST• AMPS PER CYLINDERAMPS PER CYLINDER• RELATIVE COMPRESSIONRELATIVE COMPRESSION

CYLINDER CYLINDER CONTRIBUTIONCONTRIBUTION FUEL DISTRIBUTIONFUEL DISTRIBUTION DUAL PLANEDUAL PLANE SINGLE PLANESINGLE PLANE LOW RISELOW RISE HIGH RISEHIGH RISE

COMPUTER CONTROLLED COMPUTER CONTROLLED ENGINE POWER BALANCEENGINE POWER BALANCE

DISCONNECT O2 SENSORDISCONNECT O2 SENSOR INITIAL TIMING MODEINITIAL TIMING MODE DISCONNECT EGRDISCONNECT EGR STABILIZE MAP IF APPLICABLESTABILIZE MAP IF APPLICABLE STABILIZE FUEL PRESSURESTABILIZE FUEL PRESSURE STABILIZE IDLE CONTROLSTABILIZE IDLE CONTROL PREFERRED TEST RPM 800-1200 RPMPREFERRED TEST RPM 800-1200 RPM

VOLUMETRIC EFFICIENCYVOLUMETRIC EFFICIENCY

MANUAL TEST OF MANUAL TEST OF VOLUMETRIC EFFICIENCYVOLUMETRIC EFFICIENCY

CAN TEST AT:CAN TEST AT:•CRANKINGCRANKING•IDLEIDLE•SNAP ACCELERATIONSNAP ACCELERATION

CRANKING COMPRESSION CRANKING COMPRESSION TESTTEST

SLOW CRANKSHAFT SLOW CRANKSHAFT SPEED/CYLINDER COMPLETELY SPEED/CYLINDER COMPLETELY FILLS/ HIGH COMPRESSIONFILLS/ HIGH COMPRESSION

CHECK OVERALL MECHANICAL CHECK OVERALL MECHANICAL CONDITIONCONDITION

CHECKS FOR LEAKSCHECKS FOR LEAKS

IDLING COMPRESSIONIDLING COMPRESSION

AIR RESTRICTED BY THROTTLE AIR RESTRICTED BY THROTTLE PLATEPLATE

CRANKSHAFT SPEED 4 TO 5 TIMES CRANKSHAFT SPEED 4 TO 5 TIMES CRANKING SPEEDCRANKING SPEED

LESS AIR ENTERING CYL PER LESS AIR ENTERING CYL PER ENGINE CYCLEENGINE CYCLE

TYPICALLY 50 TO 60 PSITYPICALLY 50 TO 60 PSI

CON’T NEXT SLIDE

IDLE TEST, CONT’DIDLE TEST, CONT’D

MUST “BURP” GAUGEMUST “BURP” GAUGE IF RPM BROUGHT UP SLOWLY TO IF RPM BROUGHT UP SLOWLY TO

1500 RPM, PRESSURE GOES DOWN 1500 RPM, PRESSURE GOES DOWN TO ABOUT 40 PSI.TO ABOUT 40 PSI.

NO MANUFACTURER’S SPEC NO MANUFACTURER’S SPEC COMPARE WITH OTHER CYLINDERSCOMPARE WITH OTHER CYLINDERS

SNAP ACCELERATIONSNAP ACCELERATION QUICKLY SNAP-OPEN THROTTLE, THIS QUICKLY SNAP-OPEN THROTTLE, THIS

REMOVES THROTTLE PLATE REMOVES THROTTLE PLATE RESTRICTIONRESTRICTION

READINGS SHOULD INCREASE TO 80% READINGS SHOULD INCREASE TO 80% OF CRANKING COMPRESSIONOF CRANKING COMPRESSION

HIGH READING:RESTRICTION IN HIGH READING:RESTRICTION IN EXHAUST OR VALVE TRAINEXHAUST OR VALVE TRAIN

LOW READINGS: RESTRICTED INTAKE LOW READINGS: RESTRICTED INTAKE OR CARBON ON VALVEOR CARBON ON VALVE

LAB EXERCISELAB EXERCISE

VACUUM TESTSVACUUM TESTS CYLINDER BALANCE CYLINDER BALANCE

• SEVERAL METHODSSEVERAL METHODS RUNNING COMPRESSION TESTRUNNING COMPRESSION TEST