859126 Mercruiser NUT, (.750-16)

Recommended Repairs
Complete the procedure in the order in which the steps are listed.
Table 1
Troubleshooting Test Steps Values Results
1. Battery Cables and Batteries
A. Inspect the main power switch, battery posts, and battery cables for loose connections and for corrosion. If the battery cables are corroded, remove the battery cables and clean the battery cables. Tighten any loose connections.
B. Inspect the batteries.
C. Charge the batteries. Refer to Special Instruction, SEHS7633, "Battery Test Procedure".
Test the batteries. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6 v, 8 v, and 12 v Lead Acid Batteries".
Batteries and cables
Result: The batteries and cables are not OK.
Make the necessary repairs.
Result: The batteries and cables are OK.
Proceed to Test Step 2.
2. Switches and/or Circuit Breakers
A. Check any switches and/or circuit breakers that may interfere with the engine cranking. Refer to the electrical schematic for additional information.
Switches and/or circuit breakers
Result: The switches and/or circuit breakers are not OK.
Make the necessary repairs.
Result: The switches and/or circuit breakers are OK.
Proceed to Test Step 3.
3. Starting Motor Relay, Solenoid, and Starting Circuit
A. Test the operation of the starting motor circuit. Refer to Systems Operation/Testing and Adjusting, "Electric Starting System - Test".
Starting motor relay, solenoid, and circuit
Result: The starting motor relay, solenoid, or starting circuit are not OK.
Make the necessary repairs.
Result: The starting motor solenoid and circuit are OK.
Proceed to Test Step 4.
4. Starting Motor and/or Flywheel Ring Gear
A. Test the operation of the starting motor.
B. Check the wiring for the starting motor. Refer to Systems Operation, Testing, and Adjusting, "Electric Starting System - Test".
C. Check the pinion clearance. Inspect the pinion and the flywheel ring gear for damage. Refer to Systems Operation/Testing and Adjusting, "Electrical System" for additional information.
Starter pinion and flywheel ring gear are OK
Result: The starter pinion and flywheel ring gear are not OK.
Make the necessary repairs.
Result: The starting motor and flywheel ring gear are OK.
Proceed to Test Step 5.
5. Engine Accessories and Generator
A. Ensure free movement of the driveline.
B. Remove and inspect any engine accessories that may lock up the engine.
The following list contains examples of engine accessories that may lock up the engine:
Hydraulic pump that is driven from the rear gear group
Air compressor
Engine oil pump
Other components that are driven by the engine
Engine accessories and transmission
Result: The engine accessories or generator are not OK.
Make the necessary repairs.
Result: The engine accessories and generator are OK.
Proceed to Test Step 6.
6. Hydraulic Lock
Note: If an injector has been replaced, evacuate any fluids from the cylinder and attempt to start the engine. Fuel will flow from the cylinder head into the cylinders when a unit injector is removed.
A. Check for fluid in the cylinders by removing the individual unit injectors. Check for damaged seals.
B. If there was excessive fuel in the cylinder, replace the seals and reinstall the injector. Drain any excess fuel from the cylinder head.
C. If a mechanical problem is suspected, disassemble the engine. Refer to the Disassembly and Assembly manual. Inspect the internal components for the following conditions:
Seizure
Broken components
Bent components
Hydraulic lock
Result: The engine has a hydraulic lock.
Make the necessary repairs.
Result: The engine rotates freely.
Contact the Technical Communicator at a Cat dealer.
If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).