Inspection Of Pistons - TOHATSU TLDI MD 115A SERIES Service Manual

18) Inspection of Pistons

1. Inspection of Piston Outer Diameter
Measure piston outer diameter, and replace the piston if
the outer diameter is less than the functional Limit.
Measurement Point b :
11.5 mm (0.45 in) above bottom end of piston skirt.
approximately 90 degrees from pin hole.
Standard Value a :
Standard Piston : 87.86 mm (3.4590 in)
Oversized Piston : 88.36 mm (3.4787 in)
Functional Limit a :
Standard Piston : 87.78 mm (3.4559 in)
Oversized Piston : 88.28 mm (3.4756 in)
2. Inspection of Piston Clearance
Calculate piston clearance, and if it is over the limit,
replace piston or any of piston rings, replace cylinder, or
use oversized piston.
Piston Clearance :
Standard Value : 0.15 - 0.21 mm (0.0059 - 0.0083 in)
Functional Limit :
0.30 mm (0.0118 in)
Calculation of Piston Clearance :
Cylinder Inner Diameter - Piston Outer
Diameter
Use the maximum value of the cylinder inner
diameter measured.
3. Inspection of Piston Rings
1) Push a piston ring into the cylinder by using top surface
of a piston.
2) Use thickness gauge to measure piston ring gap.
Replace piston ring if the gap is over specified value.
Thickness Gauge :
Commercially Available Item
Piston Ring End Gap : Standard Value
Top Ring
Second Ring
Third Ring
Functional Limit :
a Top Ring
b Second Ring
c Third Ring
TLDI 115A 2007
}
0.25 - 0.40 mm
(0.0098 - 0.0157 in)
}
0.8 mm
(0.0315 in)
b
a
5
5-39