Cummins/Onan GTA8.3 / GTAB.3 — Intake & Exhaust Valve Procedure
Adjustments · Cylinder head
For the Cummins/Onan GTA8.3 / GTAB.3, from the Cummins/Onan owner's manual.
Applies to: Cummins/Onan GTA8.3 engine
Before you start
- Check or set valves with engine cold below 60°C [140°F].
- Make sure timing pin is disengaged before rotating engine.
Procedure
- Remove air crossover tube (water-to-air system only).
- Disconnect support clamps and hose clamps; remove vent tube.
- Remove valve cover.
- Locate TDC for cylinder No. 1 using vibration damper marks.
- Check or set intake clearance 0.30 mm and exhaust clearance 0.61 mm with engine cold.
- Set valves per sequence with flathead screwdriver.
- Tighten locknuts to 24 Nm [18 ft-lb] and recheck lash.
- Rotate engine 360 degrees and adjust remaining valves.
- Install valve cover and torque to 24 Nm [18 ft-lb].
- Install crankcase vent tube and air crossover tube.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Intake clearance 0.30 mm [0.012 inch]
- Exhaust clearance 0.61 mm [0.024 inch]
- Locknut torque 24 Nm [18 ft-lb]
- Valve cover torque 24 Nm [18 ft-lb]
Source: Cummins/Onan 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.