Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide

Valve Seats


See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: A run-out (dial indicator) gauge is used to check valve seat concentricity

The following procedures are provided as an overview for seat replacement. Replaced valve seats must be match ground to the valves. All valve and valve seat grinding operations should be performed by a qualified machine shop; only the valve lapping operation is recommended to be performed by the home mechanic. If new valves are going to be installed a machine shop should install them. The valve seat insert must be cut to match the new valve.


To prevent damaging the other cylinder head components, completely disassemble the head.

  1. The old valve seat can be removed by machining it from the head or by heating the head in a 302-320°F (150-160°C) oil bath, then driving it from the head with a punch.

When removing the valve insert, be careful not to damage the cylinder head surface.

  1. Select a valve insert replacement and check the outside diameter, then ream the cylinder head recess at room temperature.
  3. Heat the cylinder head to 302-320°F (150-160°C) in an oil bath, then press in the new valve seat, until it seats in the recess.