Diesel engines have both an idle speed and a maximum speed adjustment. The maximum speed adjustment is a high idle speed that prevents the engine from over-revving when the control lever is in the full speed position but there is no load on the engine. No increase in power is available through this adjustment. The control lever idle stop screw is no longer used for idle speed adjustment. The idle speed boost linkage includes an adjustment for basic idle speed.
- If the vehicle has no tachometer, connect a suitable Diesel engine tachometer as per the manufacturer's instructions.
- Run the engine to normal operating temperature.
- Be sure the manual cold start/idle speed boost knob is pushed in all the way.
- Turn the linkage cap nut to adjust idle speed to 820-880 rpm, at a point where there is the least vibration.
- Advance the control lever to full speed. The high idle speed is 5300-5400 rpm. Adjust as needed and secure the locknut with sealer.