John Deere — Test Engine Compression Pressure
Testing & diagnosis · Engine system operation and test
From a John Deere service manual — check it applies to your exact model before use.
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Procedure
- Run engine until warm to normal operating temperature.
- Remove all spark plugs.
- Install JDG814 Compression Test Adapter into spark plug bore and tighten to 7 N·m (5 lb-ft).
- Connect JT01682 Gauge and Hose Assembly to adapter.
- Disconnect gas shut-off solenoid and close manual natural gas shut-off valve.
- Crank engine over at 275—325 rpm cranking speed and record compression readings.
- If pressure is low, apply oil to ring area of piston through spark plug bore and retest.
- Measure compression pressure in all remaining cylinders and compare readings.
- Recondition cylinders and valves, or replace rings and liners, as required.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 6076AFN (11:1 C/R): 1517—1724 kPa (15.1—17.2 bar) (220—250 psi)
Source: John Deere service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.