Jeep Engines - Oljeep

- --I ri4.7L POWER TECH V-8 367ICYLINDER COMBUSTION PRESSURE LEAKAGE DIAGNOSIS CHARTCONDITIONAIR ESCAPES THROUGHTHROTTLE BODYAIR ESCAPES THROUGHTAILPIPEAIR ESCAPES THROUGHRADIATORMORE THAN 50% LEAKAGEFROM ADJACENT CYLINDERSMORE THAN 25% LEAKAGE ANDAIR ESCAPES THROUGH OILFILLER CAP OPENING ONLYPOSSIBLE CAUSEIntake valve bent, burnt, or notseated DroDerlvExhaust valve bent, burnt, or notseated properlyHead gasket leaking or crackedcylinder head or blockHead gasket leaking or crack incylinder head or block betweenadjacent cylindersStuck or broken piston rings;cracked piston; worn rings and/orcylinder wallCORRECTIONInspect valve and valve seat.Reface or replace, as necessaryInspect valve and valve seat.Reface or replace, as necessaryRemove cylinder head and inspect.Replace defective partRemove cylinder head and inspect.Replace gasket, head, or block asnecessaryInspect for broken rings or piston.Measure ring gap and cylinderdiameter, taper and out-of-round.Replace defective part as necessaryI1. Disconnect the ignition coil tower electrical connectorsand remove ignition coil towers.2. Remove the spark plugs.3.4.5.6.7.Clean the spark plug recesses with compressed air.Secure the throttle in the wide-open positionDisable the fuel system. (Refer to the proper servicemanual for the correct procedure)Insert a compression pressure gauge and rotate the enginewith the engine starter motor for three revolutions.Record the compression pressure on the 3rd revolution.Continue the test for the remaining cylinders.Refer to 4.7L Engine Specifications, in this chapter, for thecorrect engine compression pressures.Engine Cylinder Head Gasket Failure DiagnosisA leaking engine cylinder head gasket usually results inloss of power, and/or coolant and engine misfiring. Anengine cylinder head gasket leak can be located betweenadjacent cylinders or between a cylinder and the adjacentwater jacket.An engine cylinder head gasket leaking betweenadjacent cylinders is indicated by a loss of powerand/or engine misfire.Cylinder-to-Cylinder Leakage TestTo determine if an engine cylinder head gasket is leakingbetween adjacent cylinders, follow the procedures outlinedin Cylinder Compression Pressure Test. An engine cylinderhead gasket leaking between adjacent cylinders will result inapproximately a 50-70% reduction in compression pressure.Cylinder-to-Water Jacket Leakage TestWarning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put your hands near the pulleys, belts or the fan. DONOT wear loose clothing.Remove the radiator cap.Start the engine and allow it to warm up until the enginethermostat opens.If a large combustiodcompression pressure leak exists,bubbles will be visible in the coolant.If bubbles are not visible, install a radiator pressure testerand pressurize the coolant system.If a cylinder is leaking combustion pressure into the waterjacket, the tester pointer will pulsate with every combustionstroke of the cylinder.An engine cylinder head gasket leaking between acylinder and an adjacent water jacket is indicated bycoolant foaming or overheating and loss of coolant.