Generac G9.0L G26 — Check Engine Compression and Condition
Testing & diagnosis
For the Generac G9.0L G26, from the Generac service manual.
Applies to: Generac 130 kW PME, Generac 150 kW PME, Generac 9.0L Gaseous Engine (G26) engine
Procedure
- Warm up the engine, if it will start and run.
- Shut engine down and remove all spark plugs.
- Use an automotive compression tester to check engine compression.
- If low, pour a small amount of clean engine oil into the spark plug opening and retest.
Tools required
- Automotive compression tester Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Standard 160 psi (12.1 kg/cm2) at 350 rpm
- Minimum 120 psi (8.4 kg/cm2) at 350 rpm
- Difference between cylinders should not exceed 15 psi (1.1 kg/cm2)
Source: Generac 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.