3861794 Volvo.Penta Propeller nut, front

Probable Causes
The following conditions can prevent operation of the starting motor:
Engaged barring device
Electrical problem
Low supply pressure
Problem with the lubricator
Problem with the starting motor's control valve
Problem with the starting motor's relay valve
Worn starting motorRecommended Repairs
Barring Device
Make sure that the barring device is fully disengaged. Inspect the fittings and the air lines of the interlock for leaks.Electrical Problem
There may be a problem with the starting system's electrical circuit. Refer to Troubleshooting, "ECM Output Circuit (Starting Motor)".Low Supply Pressure
Determine the cause of the low supply pressure. Inspect the supply lines for leaks and/or obstructions. Make the necessary repairs.Check the compressor for proper operation.If a tank is used for the supply pressure, make sure that the size of the tank is sufficient. Check the pressure in the tank.Check the pressure regulator for proper adjustment.Lubricator
Check the oil level in the lubricator and adjust the lubricator according to the engine's Operation and Maintenance Manual.Inspect the fitting of the lubricator to the air line. Make sure that the fitting is tight and free of leaks.Disassemble the lubricator and clean the parts. Inspect the parts for good condition. Replace any parts that are worn or damaged or replace the lubricator.Control Valve
Check the control valve's solenoid for proper operation. Replace the solenoid, if necessary.Relay Valve
After the starting motor's pinion is engaged, the relay valve enables a large volume of supply pressure to enter the air starting motor. Make sure that the relay valve is not stuck. Check for leaks. Check for debris in the supply line to the starting motor. Make sure that the air line is properly connected.Worn Starting Motor
Before you remove the starting motor, turn the crankshaft by hand. Ensure that a mechanical failure inside the engine is not preventing the crankshaft from turning. If the crankshaft will turn by hand, try the starting motor again. If the starting motor does not turn the crankshaft, remove the starting motor. Inspect the starting motor for worn parts.Check the starting motor for worn seals. Plug the starting motor's exhaust outlet and attach a source of pressurized air to the inlet. Submerge the starting motor in water for a minimum of 30 seconds. If bubbles rise from the starting motor, replace the seals.If a vane is cracked or if the height of a vane is less than 32 mm (1.25 inch), install new vanes.If any of the rotor bearings are loose or rough, replace the bearings.If the rotor's body is scored, try to smooth the body with emery cloth. If the body cannot be smoothed with emery cloth, replace the rotor.If the end plate is scored, use emery cloth to smooth the end plate.If the cylinder is cracked or if the cylinder is scored deeply, replace the cylinder.Air Starter Motor Pinion Does Not Engage With the Flywheel
Probable Causes
Broken clutch jawsRecommended Repairs
Repair the parts, when possible. Replace parts, if necessary. Air Starting Motor Turns Slowly or Has a Loss of Power
Probable Causes
Low air pressure
Excessive load
Incorrect adjustment of the pressure regulating valve
Incorrect lubrication
Problem with the starting motorRecommended Repairs
Low Supply Pressure
Determine the cause of the low supply pressure. Inspect the supply lines for leaks and/or obstructions. Make the necessary repairs.Check the compressor for proper operation.If a tank is used for the supply pressure, make sure that the size of the tank is sufficient. Check the pressure in the tank.Check the pressure regulator for proper adjustment.Excessive Load
Make sure that the load is not excessive. Reduce the load. If necessary, disengage the driven equipment and test the engine.Pressure Regulating Valve
Adjust the air supply pressure according to Testing and Adjusting, "Pressure Regulating Valve".Lubricator
Check the oil level in the lubricator and adjust the lubricator according to the engine's Operation and Maintenance Manual.Inspect the fitting of the lubricator to the air line. Make sure that the fitting is tight and free of leaks.Disassemble the lubricator and clean the parts. Inspect the parts for good condition. Replace any parts that are worn or damaged or replace the lubricator.Starting Motor
Inspect the starting motor for worn parts.Before you remove the starting motor, turn the crankshaft by hand. Ensure that a mechanical failure inside the engine is not preventing the crankshaft from turning. If the crankshaft will turn by hand, try the starting motor again. If the starting motor does not turn the crankshaft, remove the starting motor. Repair the starting motor or replace the starting motor.