John Deere — Check Engine Compression
Testing & diagnosis
From a John Deere service manual — check it applies to your exact model before use.
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Procedure
- Run engine at slow idle for 10 to 15 minutes
- Remove fuel injection nozzles
- Install 19.58-90.578 adapter in injection nozzle bore with R73788 nozzle spacer and 2 R92352 nozzle seals
- Attach test gauge FKM10022 to adapter
- Push throttle lever to STOP position
- Turn crankshaft for a few seconds with starting motor (minimum 150 rpm) and compare readings from all cylinders
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Minimum pressure 2400 kPa (24 bar; 350 psi)
- Maximum difference between cylinders 350 kPa (3.5 bar; 50 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.