Yanmar 3TNV Series Service Manual page 116

(4) Piston
Especially clean the combustion surface,
circumference, ring grooves and piston pin bosses,
and check after removing any carbon deposit. Any
burr at a ring groove or snap ring groove shall be
removed. If crack is suspected, inspect by color
check.
(a) Piston outside diameter measurement
Measure the long diameter at H mm from the bottom
end of the piston of the oval hole in the vertical
direction to the piston pin hole.
Piston outside diameter
Outside diameter
Model
Standard
3TNV82A 81.950 81.980
3,4TNV84(T) 83.945 83.975
3,4TNV88 87.945 87.975
4TNV94L 93.945 93.955
4TNV98(T) 97.940 97.950
4TNV106(T) 105.930 105.960
If the clearance between piston and cylinder exceeds
the limit, use an oversized piston. (Refer to the tables
of oversized pistons, oversized piston rings and
cylinder boring dimension on 4.4.5(1)(c) in chapter 4.)
(b) Piston pin hole measurement
Measure the outside diameter of piston pin and the
inside diameter of piston pin hole. Calculate the
clearance between piston pin and piston pin hole. If
any data exceeds the limit, replace the part with a new
one.
Model Item
Pin I.D.
3TNV82A Pin O.D.
Clearance
Pin I.D.
TNV84 88 Pin O.D.
Clearance
Pin I.D.
4TNV94L
Pin O.D.
4TNV98(T)
Clearance
Pin I.D.
4TNV106(T) Pin O.D.
Clearance
Limit
81.905
83.900
87.900
93.900
97.895
105.880
mm
Standard Limit
23.000 23.009 23.039
22.995 23.000 22.965
0.000 0.014 0.074
26.000 26.009 26.039
25.995 26.000 25.965
0.000 0.014 0.074
30.000 30.009 30.039
29.989 30.000 29.959
0.000 0.020 0.080
37.000 37.011 37.039
36.989 37.000 36.959
0.000 0.022 0.080
101
4. Disassembly, Inspection and Reassembly of Engines
Clearance between
piston and cylinder
0.035 0.065
0.040 0.070
0.050 0.080
mm
Measurement
position (H)
22 25
22
22
30