Detroit Diesel — Compensation Needle Valve Adjustment (PSG Governor)
Adjustments · Governor compensation needle valve
From a Detroit Diesel service manual — check it applies to your exact model before use.
Before you start
- Closing the valve farther than necessary makes the governor slow in returning the engine to normal speed after a load change.
Procedure
- Open the compensation needle valve two or three turns and allow engine to hunt or surge for about one-half minute to bleed trapped air.
- Gradually close the valve until hunting just stops.
- Check valve opening by closing completely and noting number of turns required, then reopen to the position at which hunting stopped.
- Test governor action by manually disturbing engine speed; engine should return promptly with only a small overshoot.
- Correct valve setting is between 1/8 and 1/2 turn open.
Specs & values
- 1/8 to 1/2 turn open
Source: Detroit Diesel 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.