Repair; Expansion Plugs - Mercury MerCruiser D2.8L D-Tronic Service Manual

ENGINE MECHANICAL

Repair

Expansion Plugs

1. Apply Loctite 290 to outer diameter of expansion plugs.
2. Install plugs flush to outer surface of cylinder head.
VALVE SEAT RECONDITIONING
Several different types of equipment are available for reconditioning valve seats. Equipment
manufacturer's recommendations should be followed carefully to attain proper results.
Regardless of type of equipment, however, it is essential that valve guide bores be free from
carbon or dirt to insure proper centering of pilot in valve guide.
Machine valve seat angles to the following specifications:
Intake
Exhaust
VALVE SEAT REPLACEMENT
1. To replace the seats, heat the head in an oven to 150 degrees C (300 degrees F.).
Remove old seat. Do NOT damage counterbore.
To avoid distortion or melting of aluminum heads, Do NOT use a torch to replace
valve seats.
2. Clean dirt from counterbore. Check counterbore for nicks and scratches.
3. Reheat head in oven to 150 degrees C (300 degrees F.).
4. Cool new seat in liquid nitrogen and install in counterbore. Seat should fit without using
pressure. Allow to cool.
Page 3A-50
a
a - Expansion Plugs
Valve Seat Machine Angle
CAUTION
SERVICE MANUAL NUMBER 22
a
30 degrees
45 degrees
90-860074--1 FEBRUARY 2002
75101