Wrangler 4WD L4-150 2.5L VIN P MFI (1998)
Cylinder Head Gasket: Testing and Inspection
WARNING: Use extreme caution when the engine is operating. Do not stand in a direct line with the fan. Do not put your hands near the
pulleys, belts or the fan. do not wear loose clothing.
FAILURE DIAGNOSIS
A leaking engine cylinder head gasket usually results in loss of power, loss of coolant and engine misfiring. An engine cylinder head gasket leak
can be located between adjacent cylinders or between a cylinder and the adjacent water jacket.
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An engine cylinder head gasket leaking between adjacent cylinders is indicated by a loss of power and/or engine misfire.
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An engine cylinder head gasket leaking between a cylinder and an adjacent water jacket is indicated by coolant foaming or overheating and
loss of coolant.
Cylinder-To-Cylinder Leakage Test
To determine if an engine cylinder head gasket is leaking between adjacent cylinders follow the procedures outlined in Cylinder Compression
Pressure Test. An engine cylinder head gasket leaking between adjacent cylinders will result in approximately a 50 - 70% reduction in
compression pressure.
Cylinder-To-Water Jacket Leakage Test
1. Remove the radiator cap.
2. Start the engine and allow it to warm up until the engine thermostat opens.
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If a large combustion/compression pressure leak exists, bubbles will be visible in the coolant.
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If bubbles are not visible, install a radiator pressure tester and pressurize the coolant system.
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If a cylinder is leaking combustion pressure into the water jacket, the tester pointer will pulsate with every combustion stroke of the
cylinder.
