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Home›Repair guides›Generac›Check Valve Clearance

Generac — Check Valve Clearance

Maintenance · Engine Valve System

From a Generac owner's manual — check it applies to your exact model before use.

Applies to: Generac 15 kW EcoGen, Generac GT-999 engine

Before you start

  • AVR charged up to 3 minutes after power down. Wait 5 minutes before removing filter housing.
  • Perform with engine at ambient air temperature.
  • If uncomfortable or tools unavailable, contact authorized service dealer.

Procedure

  1. Verify engine at ambient air temperature.
  2. Remove AVR filter housing screw from back panel.
  3. Remove AVR filter housing.
  4. Depress external latch to disconnect 20-pin connector from AVR.
  5. Remove two screws to release AVR brackets from back panel.
  6. Remove spark plug cables from spark plug terminals by grasping boot.
  7. Thoroughly clean area around spark plugs.
  8. Remove spark plugs using 5/8 inch spark plug socket.
  9. Remove four screws to release valve cover.
  10. Move piston to Top Dead Center (TDC) of compression stroke.
  11. Remove intake screen at front of engine to access flywheel nut.
  12. Place large socket and wrench on flywheel nut, rotate engine clockwise watching piston through spark plug hole.
  13. Piston at TDC when at highest point of travel.
  14. Insert 0.002-0.004 inch (0.05-0.1 mm) feeler gauge between rocker arm and valve stem.
  15. Verify clearance with slight drag felt sliding feeler gauge back and forth.

Tools required

  • 5/8 inch spark plug socket Amazon
  • Feeler gauge (0.002-0.004 inch / 0.05-0.1 mm) Amazon
  • Large socket and socket wrench Amazon
  • Intake screen removal tool Amazon

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • Valve clearance (Intake): 0.002-0.004 inch (0.05-0.1 mm)
  • Valve clearance (Exhaust): 0.002-0.004 inch (0.05-0.1 mm)
  • Check interval: after first 25 hours
  • Full adjustment interval: 1000 hours or 4 years

Full service-parts list: Generac 15 kW EcoGen →

Source: Generac owner's 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.

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