Valve Seat Replacement

WARNING: This page is about a different car, the 2005 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.

Bore out old seat until it collapses. Boring should not continue beyond the bottom face of the seat recess in cylinder head. Set the machine depth stop to ensure this.
Ream cylinder head recess for service valve seat.
- Oversize: 0.5 mm (0.020 in)
- Intake: 38.500 - 38.516 mm (1.5157 - 1.5164 in)
- Exhaust: 32.700 - 32.716 mm (1.2874 - 1.2880 in)
- Be sure to ream in circles concentric to the valve guide center.
- This will enable valve seat to fit correctly.
  
  Fig 1: Identifying Valve Seat Recess Diameter
  Courtesy of NISSAN MOTOR CO., U.S.A.
Heat cylinder head to 110° - 130°C (230° - 266°F) by soaking in heated oil.
WARNING: Cylinder head is hot. Wear protective equipment to prevent getting burned.
Press fit valve seat until it seats on the bottom.
Cut or grind valve seat using suitable tool to the specified dimensions. Refer to VALVE .
After cutting, lap valve seat with abrasive compound.
Check valve seating condition.
- Seat face angle "alpha;": 45° 25' - 46° 15' degrees/minutes (45.42° - 46.25° degree decimal)
- Contacting width "W" for intake: 1.09 - 1.31 mm (0.0429 - 0.0516 in)
- Contacting width "W" for exhaust: 1.29 - 1.51 mm (0.0508 - 0.0594 in)
Fig 2: Identifying Seat Face Angles
Courtesy of NISSAN MOTOR CO., U.S.A.
Use a depth gauge to measure the distance between the mounting surface of the cylinder head spring seat and the valve stem end. If the distance is shorter than specified, repeat step 5 to adjust it. If it is longer, replace the valve seat with a new one.
- Valve seat resurface limit "L" intake: 41.07 - 41.67 mm (1.6169 - 1.6405 in)
- Valve seat resurface limit "L" exhaust: 41.00 - 41.60 mm (1.6142 - 1.6378 in)
Fig 3: Identifying Valve Seat Resurface Limits
Courtesy of NISSAN MOTOR CO., U.S.A.