Great Wall GW491QE, Service Manual

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EM.1-14
(c)The฀measured฀value฀of฀diameter฀for฀piston฀shall฀be฀reduced฀by฀that฀for
the฀engine฀body.
Standard฀piston฀clearance (0.065 0.085)mm
Oper ation฀limit: 0.085฀mm
If฀the฀actual฀piston฀clearance฀is฀greater฀than฀Max.฀value,฀all฀pistons฀for฀four
cylinders฀must฀be฀changed,฀and฀/or฀four฀cylinders฀must฀be฀re-bored.
3.฀Measure฀the฀clearance฀between฀the฀piston฀ring-groove฀and
the฀piston฀ring
(a)Aclearancegaugemaybeusedtomeasuretheclearancebetweennew฀piston฀ring฀and
ring-groove.
฀฀ Standard฀ring-groove฀clea(0.03~0.075)mm
Max฀ring฀grooveclearance0.2mm
(b)The฀piston฀shall฀be฀changed฀if฀the฀actual฀clearance฀is฀greater฀than฀Max.฀value.
4.฀Check฀the฀clearance฀of฀opening฀for฀piston฀ring
(a) Install฀the฀piston฀ring฀into฀cylinder.
(b) The฀piston฀ =ring฀ may฀ be฀ pushed฀ to฀ the฀ end฀ of฀ stroke฀ by฀ piston,
then฀a฀measurement฀may฀proceed฀using฀chock฀gauge.
(c) A฀feeler฀gauge฀may฀be฀used฀to฀measure฀the฀clearance฀ofopening.
-If฀the฀actual฀opening฀clearance฀is฀greater฀than฀Max.฀value,฀thepiston฀ring฀shall
be฀changed.
-If฀the฀actual฀opening฀clearance฀is฀still฀greater฀than฀Max.฀valueafter฀a฀replacement
with฀new฀piston฀ring,฀the฀cylinder฀shall฀be฀rebored,฀and฀piston฀ring฀with฀an
increased฀size฀shall฀be฀used.฀It’sstrictly฀prohibited฀to฀file฀the฀end฀of฀pistonring.
The฀opening฀clearance฀of฀piston฀ring mm
฀5.฀Inspection฀on฀connection-rod
(a)A฀straightener฀may฀be฀used฀to฀check฀the฀linearity฀of฀connection-rod฀in฀follo
wing฀aspects:
-฀Check฀the฀bending฀deformation.
Max.฀bending฀deformation 0.05฀mm/100฀mm
T he฀ connection-rod฀ component฀ shall฀ be฀ changed฀ if฀ the฀ actual฀ bending
deformation฀is฀greater฀than฀Max.฀value.
R ing
value
1
st
ring 2
nd
ring Oil ring
Standard
value
Max.
value
Preparations฀before฀and฀key฀points฀to฀the฀disassembly฀of฀engine฀body
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