Powerhead Break In Procedures

POWERHEAD BREAK-IN PROCEDURE
This is a guideline for breaking in a new powerhead. It’s always best to consult a professional for the installation of the new powerhead. Powerhead failure is typically due to excessive combustion chamber temperature. You must identify and address the cause of this failure, or the same problem will recur. Our experience shows that the piston is often the first component to fail, usually due to detonation. The following tips may help you avoid repeat failure:
General Recommendations
  • Fuel System:
    • Have all injectors cleaned and flow-tested. Replace any injectors that are out of specification.
    • Inspect the entire fuel system, including the fuel pump, line filters, carburetors, etc.
    • Verify high and low fuel pressures are within manufacturer specifications.
    • Use mid-grade octane fuel from a major manufacturer, without alcohol.
  • Ignition and Timing:
    • Retard ignition timing by 2 degrees.
    • Replace or check all switch boxes and ignition modules.
  • Cooling System:
    • Replace the water pump and all gaskets at the time of powerhead replacement and annually thereafter. Use the newest-style gaskets.
    • We recommend installing a water pressure gauge to monitor water flow in the engine.
  • Oil System:
    • We recommend removing the oil injection system or updating to the latest VRO pump (if applicable).
    • Clean and refill the oil tank with TCW-3 oil from a major manufacturer.
    • Verify oil consumption by marking the oil tank during the break-in period.
    • Double the oil mixture for approximately 30 gallons of fuel during break-in:
      • If running oil injection, add 1 pint of TCW-3 oil to 6 gallons of gas.
      • If no oil injection, add 1 quart of TCW-3 oil to 6 gallons of gas. (Note: Does NOT apply to direct-injected motors.)
  • Post-Installation:
    • Re-torque cylinder heads after 1 hour of running time, once the engine has cooled.
    • Check the overheat and oil alarm horn for proper function.
    • Rebuild carburetors and/or fuel pump as needed.
Specific Recommendations by Engine Type Carbureted OMC-Johnson-Evinrude
  • Increase main metering jets by 0.002 inches.
  • Retard maximum timing by 2 degrees. Set max timing with the engine running over 4500 RPM under load (do not set max timing statically).
  • On 3-cylinder engines, replace the water pump with the late-model high-pressure style and jet carburetors per OMC service bulletins.
Carbureted & EFI Mercury V6
  • Increase main metering jets by 0.002 inches in carburetors.
  • Rebuild or replace carburetors and fuel pump.
  • Retard maximum timing by 2 degrees.
  • Remove the advance module and idle stabilizer (if equipped).
  • If retaining oil injection:
    • Replace the 2-PSI oil valve.
    • Check the oil pump bushing and seal.
  • Ensure trigger wires on the flywheel move freely for proper timing advance.
  • Re-torque 2.0/2.4/2.5 cylinder heads to 40 ft-lbs after 1 hour of running time, once cooled.
  • Check the overheat alarm system and horn. Be aware of potential issues with the detonation sensor and module.
  • On 2.5 EFI engines:
    • Note that there may be up to seven fuel filters.
    • Remove the cone-shaped filter in the line below the electric pump.
    • Verify fuel pressure meets specifications.
Additional Notes
  • Always consult the latest factory specifications and service bulletins for your specific engine model.