S 420 (140.043) V8-4.2L (119.981) (1996)
Compression Check: Testing and Inspection
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Warm engine up to operating temperature.
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Remove spark plugs.
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Blow out spark plug recesses with compressed air.
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Crank engine with starter to expel residues and soot, refer to Cranking Engine With Starter For Testing. See: Engine, Cooling and
Exhaust/Engine/Service and Repair
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Insert diagram sheets (03) into compression tester (01).
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Push compression tester (01) into spark plug hole of relevant cylinder.
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Crank Engine about 8 revolutions with starter.
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Check all the cylinders in this way.
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If minimum compression pressure not reached, check cylinders with cylinder leak tester.
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Install spark plugs.
Test Data For Engine At Normal Operating Temperature
Compression pressure at:
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Normal compression
Minimum 10 bar
Maximum 14 bar
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Fuel-optimized
Minimum 6 bar
Maximum 10 bar
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Permissible difference between individual cylinders
Maximum 1.5 bar