Crowley Marine: serving boaters for over 50 years Crowley Marine: serving boaters for over 50 years
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Mercury/Mariner V6 Powerhead Installation

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  1. Check latest Mercury Service Bulletins.

  2. Install .0002" larger jets in carburetors.

  3. Max timing should be retarded 2 degrees.

  4. Remove advance box if installed.

  5. Remove idle stabilizer if installed.

  6. Rebuild carburetors and fuel pump.

  7. Retorque heads to 40 ft/lbs.

  8. After 1 hour running, allow engine to cool and recheck torque. Retorque to factory specs if necessary.

  9. Crowley Marine suggests removing oil injection system.

  10. If oil injection is used, replace 2 PSI oil valve and check oil pump bushing and seal.

  11. Clean and refill oil tanks with TCW-3 oil.

  12. Verify oil consumption during break-in by marking the oil tank level.

  13. Check overheat alarm system and horn.

  14. On 2.5 EFI engines, fuel pressure should be 39 lbs. minimum.

  15. 2.5 EFI engines may have as many as 7 fuel filters, remove the cone shaped filter inline below the electric pump.

  16. Use newest style head gaskets and replace every year to prevent failure.

  17. Replace water pump impeller and gasket every year to prevent head gasket failure.

  18. Use 92-94 octane premium fuel.

Carefully following these instructions will aid in the proper assembly & break-in of your Mercury V6 engine

MYP605R - Mercury/Mariner V6 2.0L 135-150HP 1991-2001
MYP616R - Mercury/Mariner V6 2.5L Carb & EFI 150-200HP 1991-2010
MYP607R - Mercury/Mariner V6 2.5L DFI (Optimax) 135-175HP 1998-2014
MYP634MR - Mercury/Mariner V6 2.5L ProMax 200-225HP 1994-2002
MYP635JR - Mercury/Mariner V6 2.5L Sport Jet 175-240HP 1997-2006
MYP637R - Mercury/Mariner V6 3.0L Carb & EFI 200-250HP 1994-2008
MYP670R - Mercury/Mariner V6 3.0L Pro XS 225-250HP 2004-2014
MYP6F20R - Mercury/Mariner V6 4-Stroke 225HP 2004-Current

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