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Home >> Mercedes Benz >> 1992 >> 400E (124.034) V8-4.2L (119.975) >> Repair and Diagnosis >> Powertrain Management >> Tune-up and Engine Performance Checks >> Compression Check >> Testing and Inspection
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Compression Check: Testing and Inspection







- Warm engine up to operating temperature.
- Remove spark plugs.
- Blow out spark plug recesses with compressed air.
- Crank engine with starter to expel residues and soot, refer to Cranking Engine With Starter For Testing. Service and Repair
- Insert diagram sheets (03) into compression tester (01).
- Push compression tester (01) into spark plug hole of relevant cylinder.
- Crank Engine about 8 revolutions with starter.
- Check all the cylinders in this way.
- If minimum compression pressure not reached, check cylinders with cylinder leak tester.
- Install spark plugs.

Test Data For Engine At Normal Operating Temperature
Compression pressure at:
- Normal compression
Minimum 10 bar
Maximum 14 bar
- Fuel-optimized
Minimum 6 bar
Maximum 10 bar
- Permissible difference between individual cylinders
Maximum 1.5 bar

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