Explorer GT 50, Service And Maintenance Manual

Page: 40 / 112

43
Unit ᧶ mm
Piston pin bore
Use a caliper gauge to measure the piston pin bore inside diameter,.
If reading exceeds the following service limit, replace it with a new
one.
(Dial caliper)
Limit service: 12.30mm(0.4736in)
Piston pin outside diameter
᧶
Use a micrometer to measure the piston outside diameter at three
positions.
(Micrometer ᧤ 0-25mm ᧥ )
service limit
᧶
11.980mm(0.4717in)
Piston rings
Check each ring for end gap, reading the gap with a
thickness gauge shown in the illustration. If the end gap is found
to exceed the limit, indicated below, replace it with a new one.
The end gap of each ring is to be measued with the ring fitted
squarely into the cylidner bore and held at the least worn part
near the cylidner bottom, as shown in the illustration.
Service limit
᧶
0.75mm(0.030in)
As the piston ring wears, its end gap increases reducing reducing
engine power output becaust of the resultant blow by through the
enlarged gap. Here lies the importance of using piston rings with
end gaps with the limit. Measure the piston ring free end gap to
check the spring tension.
service limit
᧶
3.6mm(0.14in)
Fix the piston ring in the piston ring groove, measure the ring
side clearance with the thicknes gauge while matching the
sliding surface of piston and ring.
Standard service limit
Cylinder 40.005-40.020 40.075
Piston 39.94-39.955 39.885
Cylinder to piston 0.06-0.07 0.120