How to Calibrate the Valve seat of Yanmar 3TNV Series and 4TNV Series Engines

 This article introduces how to calibrate the valve seat of yanmar 3TNV series and 4TNV series engines

 For Yanmar Diesel Engine Agriculture Excavator Tractor Marine Generator Diagnostic tool

[NOTICE]

Always check the oil clearance between the valve and valve guide before correcting the valve seat.     If it exceeds the limit, replace the valve or valve guide first to make the clearance satisfy the standard. After correction, wash the valve and the cylinder head sufficiently with diesel oil to remove all grinding powder or compound.

1) If the seat surface is slightly roughened: perform

[A] and [B] below.

[A]: Lap the valve and seat with a mixture of valve compound and engine oil.

[B]: Lap with engine oil only.

2) If the seat is heavily roughened but the width is    almost normal, correct with a seat grinder or seat cutter first.   Then perform lapping [A] and [B].

  09.2024 Yanmar SA-Direct 2.45 Offline Diagnostic Software

 

3) If the seat is heavily roughened and the width is   much enlarged, grind the seat inner surface with  a seat grinder whose center angle is 40。, then   grind the seat outer surface with a grinder whose center angle is 150。to make the seat width

match the standard.   Then perform seat

correction as described in 2), and then carry out lapping [A] and [B].

 

2018 Yanmar Engine Diagnostic Service Tool Software

 

 

How to Disassemble the Yanmar 3TNV series and 4TNV series Engine Cylinder Head: Disassembly, Inspection and Reassembly

 This article describes how to disassemble the Yanmar 3TNV series and 4TNV series engine Cylinder Head: Disassembly, Inspection and Reassembly

 For Yanmar Diesel Engine Agriculture Excavator Tractor Marine Generator Diagnostic tool

 

 09.2024 Yanmar SA-Direct 2.45 Offline Diagnostic Software

  Disassembly procedure:

Disassemble in the order of the numbers shown in the illustration.

1) Remove the alternator assy. (Point1)

2) Remove the fan, pulley and V belt.

    3) Remove the thermostat case. (Point2)

                        4) Remove the fuel filter and fuel oil piping. (Point3) 

5) Remove the oil level gage assy. 

6) Remove the oil filter. (Point4)

            7) Remove the fuel injection pipes. (Point5)

8) Remove the intake manifold assy.

9) Remove the exhaust manifold assy.

10) Remove the rocker arm cover Assy.

                                              11) Remove the rocker shaft assy, push rods and valve caps. (Point6)

                                12) Remove the cylinder head assy and head gasket. (Point7)

                                       13) Remove the fuel injection valves and fuel return pipe. (Point8)

                                             14) Remove the intake/exhaust valves, stem seals and valve springs. (Point9)

15) Remove the rocker arms from the rocker shaft.

2018 Yanmar Engine Diagnostic Service Tool Software