73379 Mercruiser PLUG, (.250-18), PIPE - EXHAUST MANIFOLD

Recommended Actions
Diagnostic Codes
Check for active diagnostic codes on the electronic service tool. Troubleshoot any active codes before continuing with this procedure.ECM Software
Connect the electronic service tool to the diagnostic connector and check for the following conditions:
Check for the correct engine serial number
Check for the correct arrangement number
Check for the correct software
Use the electronic service tool to verify any active diagnostic codes.
If diagnostic codes are present, the Electronic Control Module (ECM) must be programmed with the correct information.
If the repairs have not eliminated the fault proceed to "Air Intake System or Exhaust System". Air Intake System or Exhaust System
Use the electronic service tool to check for an air filter restriction.
Ensure that the air filter is clean and serviceable.
Check the air intake and the exhaust system for the following defects:
Blockages
Restrictions
Damage to the air intake and exhaust lines and hoses
Make all necessary repairs to the engine.
If the fault has not been eliminated, proceed to "Valve Lash". Valve Lash
Ensure that the valve lash is correct. Reset the valve lash if it is not correct. Refer to Systems Operation, Testing and Adjusting, "Engine Valve Lash - Inspect/Adjust".If the repair does not eliminate the fault proceed to "Turbocharger".Turbocharger
Note: The turbocharger that is installed on this engine is a nonserviceable item. If any mechanical fault exists, except for the wastegate actuator, then the turbocharger must be replaced. The wastegate actuator can be replaced.
Ensure that the mounting bolts for the turbocharger are tight.
Check that the oil drain for the turbocharger is not blocked or restricted.
Check that the compressor housing for the turbocharger is free of dirt, debris and damage.
Check that the turbine housing for the turbocharger is free of dirt, debris and damage.
Check that the turbine blades rotate freely in the turbocharger.
Ensure that the wastegate on the turbocharger is adjusted correctly. Refer to Systems Operation, Testing and Adjusting, "Wastegate - Inspect". If the wastegate actuator is faulty, replace the wastegate actuator. Refer to Disassembly and Assembly, "Turbocharger - Disassemble" and Disassembly and Assembly, "Turbocharger - Assemble".
If necessary, replace the turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".
Check that the repairs have eliminated the faults.
If the repairs have not eliminated the fault proceed to "Low Compression (Cylinder Pressure)". Low Compression (Cylinder Pressure)
Perform a compression test. Refer to Systems Operation, Testing and Adjusting, "Compression - Test ".
If low compression is noted on any cylinders, investigate the cause and rectify the cause. Possible causes of low compression are shown in the following list:
Loose glow plugs
Faulty piston
Faulty piston rings
Worn cylinder bores
Worn valves
Faulty cylinder head gasket
Damaged cylinder head
Perform all necessary repairs.
Ensure that the repairs have eliminated the faults.
If the repair does not eliminate the fault refer to "Individual Malfunctioning Cylinder". Individual Malfunctioning Cylinder
With the engine speed at a fast idle, use the electronic service tool to isolate one cylinder at a time. Note if there is any reduction in engine speed. If a reduction in engine speed is not noted, the isolated cylinder is not operating under normal conditions. If the isolation of a particular cylinder results in a reduction of engine speed that is less than normal, this may indicate that the cylinder is operating below normal performance. Investigate the cause of the fault on any cylinder that is not operating. Investigate the cause of the fault on any cylinder that is operating below normal performance.
If all cylinders have been checked and no faults were detected proceed to "Electronic Unit Injectors". Electronic Unit Injectors
With the engine speed at a fast idle, use the electronic service tool to isolate one cylinder at a time. Note if there is any reduction in engine speed. If a reduction in engine speed is not noted, the isolated electronic unit injector is not operating under normal conditions. If the isolation of a particular cylinder results in a reduction of engine speed that is less than normal, this may indicate that the electronic unit injector is operating below normal performance.
Remove the electronic unit injector from the suspect cylinder. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove".
Install a new electronic unit injector. Refer to Disassembly and Assembly, "Electronic Unit Injector - Install".
Repeat the test in 1. If the fault is still apparent, remove the replacement electronic unit injector and install the original electronic unit injector. Refer to Disassembly and Assembly, "Electronic Unit Injector - Remove" and Disassembly and Assembly, "Electronic Unit Injector - Install".
If the fault is not eliminated, refer to the Troubleshooting Manual for your engine application.