Ring2: 0.20 to 0.40mm;
Oil ring: 0.20 to 0.7mm.
Maximal opening clearance:
Ring1: 1.05mm;
Ring2: 1.20mm;
Oil ring: 1.10mm.
d. If the opening clearance is greater than the maximal value, replace the piston ring.
e. If the opening clearance is still greater than the maximal value after installing the new piston ring, re-bore the 4 cylinders
or replace the cylinder block.
11. Check the radial run-out of crankshaft
(1) Put the crankshaft upon the V-shaped block.
Fig. 56 Check and Measure the Main
Journal and the Connecting Rod Journal
of Crankshaft
Fig. 55 Check and Measure the
Radial Run-out of Crankshaft
(2) Measure the radial run-out of the central journal (Fig. 55). The
maximal standard of radial run-out is 0.03mm. If the measured radial
run-out is greater than the maximal value, replace the crankshaft.
12. Check the main journal and the connecting rod journal
(1) Measure diameter of each main journal and connecting rod
journal with micrometer (Fig. 56).
Diameter of main journal and connecting rod journal refers to table 4:
If the measured diameter fails the requirement, check the oil film
clearance, and grind or replace the crankshaft if necessary.
(2) Check the cylindricity of each main shaft journal and connecting
rod journal.
Maximal cylindricity: 0.02mm. If the measured cylindricity is greater
than the maximal value, replace the crankshaft. If necessary, grind
the main journal or the connecting rod journal till the diameter is
smaller than that of the finished product, and install the bearing shell
matching the new dimension in order to make sure the oil film clear-
ance is qualified.
(III) Bore and Grind the Cylinders
If the cylinder hole wears so much that the cylinder shall be bored, the
4 cylinders must be bored and ground, and equipped with the extra-
dimension pistons. Replace all the piston rings to match the extra-
dimension pistons. Take MR479Q for example:
1. Install the extra-dimension pistons
Diameter of extra-dimension pistons:
Extra-dimension 0.50 (type): 79.155 to 79.185mm.
2. Calculate the cylinder-boring quantity
(1) Measure the piston diameter vertical to the central line of piston
pin at 18mm away from the piston bottom side with micrometer (Fig.
51).
(2) Calculate the re-boring quantity for each cylinder according to the
formula below. The re-boring distance
39
Содержание JL481Q
Страница 1: ......
Страница 9: ...5 Fig 3 Components Assembly Drawing of MR479Q MR479QA Engine ...
Страница 10: ...6 Fig 4 MR479Q MR479QA Engine and Its Power System ...
Страница 11: ...7 Fig 5 Assembly Drawing of Engine and Its Auxiliaries MR479Q MR479QA ...
Страница 12: ...8 Fig 6 Electronic Control Fuel Injection System in Engine MR479Q MR479QA ...
Страница 13: ...9 Fig 7 Front view of Engine JL481Q MR481QA ...
Страница 14: ...10 Fig 8 Sectional elevation of Engine JL481Q MR481QA ...
Страница 15: ...11 Fig 9 Electronic Control Fuel Injection System in Engine JL481Q MR481QA ...
Страница 21: ...17 Fig 13 Exterior Feature of JL481Q Engine Power Me N m Torque Pe Kw ge g kwh Fuel Consumption Ratio ...