Piston: Service and Repair

CYLINDER BLOCK, PISTON AND CONNECTING ROD ASSEMBLY SERVICE










(1) Mark piston with matching cylinder number as shown.

(2) Mark connecting rod and cap before removing.

(3) Arrow on piston top must face timing belt end of engine.









(4) Oil slot on connecting rods does not indicate rod direction.

(5) Each rod and cap are stamped with matched reference numbers on one side only. The assembly MUST be installed with these matched (rod and cap) numbers facing the flywheel end of engine, opposite direction of the piston arrow.





Piston-Piston Pins-Rings










(1) Pry out the piston pin lock-rings using a suitable tool and taking care not to ruin the piston seats.

(2) Remove the pin by tapping on it with a properly sized punch.

(3) Mark the pins and connecting rods to indicate their piston number.


CAUTION: If reused, the piston pins must be remounted in the original position, to ensure an exact match with the pistons.


(4) Make sure the dimensions of the piston holes fall within the limits indicated in piston pins, connecting rods.

(5) Check the diameter clearance between piston pins and connecting rods.

(6) Mark the rings so that each one can be installed in its original position (if reused).

(7) Insert all the rings one by one in their respective cylinders about 16 mm (.62 in.) from the top of the cylinders and check the end gap of the rings with a feeler gauge to make sure it falls within the specifications.

If the gap exceeds the wear limit, measure the inside diameter of the cylinders.

Replace rings if the internal diameter of the cylinder does not exceed the service limit.

(8) Measure the piston diameter, remembering that there are two size classes of pistons and cylinder bores, according to the following table:


Class Bore Diameter Piston Diameter
A 87.474mm 87.474-87.429 mm
B 87.487 mm 87.429-87.442 mm


The size class of each bore is shown at the bottom of the crankcase (oil pain side).

(9) Visually check for grooving or traces of wear. Then measure the inside diameter of each cylinder at three different heights and in two different directions offset by 9°.



To determine the degree of cylinder wear, consider the maximum reading of the bore gauge.



Removing and Installing Piston Rings


When installing the piston rings make sure that the end of each ring lines up with the pins installed in the piston seats.

The two upper piston rings are identical.

(1) "Top" mark on upper and intermediate piston rings must point toward piston crown.









(2) Using a suitable ring expander, remove or install upper and intermediate piston rings.

(3) For installation of the oil ring, start with oil ring expander. Place expander in lower oil ring groove and install oil rails. Steel oil ring gaps should be installed 180° apart from each other.











Check piston ring to piston ring groove clearance with feeler gauge.















Groove Clearance


(1) Upper Piston Ring 0.038 to 0.078mm 0.10mm
(2) Intermediate Piston Ring 0.038 to 0.043mm 0.10mm
(3) Oil Control Ring 0.2mm (.008 in.) side
Should be free in groove, not to exceed 0.2mm (.008 in.) side clearance.



Piston Ring Gap







(1) Using a piston, push piston ring into cylinder bore approximately l6mm (.62 in.) from bottom.




Ring Gap
Upper Ring 0.23 to 0.48mm
Intermediate Ring 0.23 to 0.48mm
Oil Ring 0.38 to 1.40mm










(1) Cylinder bore check. Bore size is shown at the bottom of the crankcase.










(1) Measure at points 1, 2 and 3 first in direction A then direction B.

1. = lOmm (3/8 in.) from top
2. = middle of cylinder wall
3. = lOmm (3/8 in.) from bottom