Cummins/Onan — Turbocharger Boost Pressure - Adjustment for Site Altitude
Adjustments · Turbo boost controller
From a Cummins/Onan owner's manual covering: G 12, G28, G855, GTA12, GTA19, GTA28, GTA855. Check it applies to your exact model before use.
Applies to: Cummins/Onan G 12, Cummins/Onan G&855, Cummins/Onan GTA855
Before you start
- Excessive turbo boost may cause an engine failure.
Procedure
- Refer to the RED tag attached to the controller specifying the factory setting for altitude and horsepower.
- Make sure that the engine has been stopped.
- Disconnect the hose located at the bottom of the controller.
- Remove the end cap from the cylinder by pushing in and rotating in a counterclockwise direction.
- Install or remove spacers between the cap and spring to achieve the proper setting (see site altitude Table #8-12).
- Loosen the lockscrew on the Turbo Boost Controller butterfly lever and adjust to a fully opened position. Tighten lockscrew on lever.
- Start the engine and record Turbo Boost at full load condition.
- Repeat steps 6 and 7 every time a shim or spring is removed.
Specs & values
- See site altitude Table #8-12 number of spacers
Full service-parts list: Cummins/Onan G 12 →, Cummins/Onan G&855 →
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.