Part 2
PISTONS AND CONNECTING RODS
Removal
Follow removal steps outlined in illustration.
Removal Service Points
[A] Connecting Rod Cap Removal.
1. Mark the cylinder number on the side of the connecting rod big end for correct reassembly.
2. Keep the removed connecting rods, caps, and bearings in order according to the cylinder number.
[B] Removal Of Piston Pin.
1. Remove the snap rings.
2. Heat the piston to approximately 70° C (158° F) and pull out the piston pin.
CAUTION: Apply an ample coat of engine oil to the periphery of the piston pin and the hole of the connecting rod small end.
The clearance between the piston and the piston pin is an almost tight fit at normal temperature. Therefore, be sure to heat the piston before pulling out the piston pin.
In addition, note that the piston is hot after heating.
Inspection
Piston
1. Replace the piston if scratches or seizure are evident on its surfaces (especially the thrust surface). Replace the piston if it is cracked.
Piston pin
1. Insert the piston pin into the piston pin hole with a thumb. You should feel a slight resistance. Replace the piston pin if it can be easily inserted or there is an excessive play.
2. The piston and piston pin must be replaced as an assembly.
Piston Ring
1. Check the piston ring for damage, excessive wear, and breakage and replace if defects are evident. If the piston has been replaced with a new one, the piston rings must also be replaced with new ones.
2. Check for clearance between the piston ring and ring groove. If the limit is exceeded, replace the ring or piston, or both.
Standard value:
No. 1 0.03 - 0.07 mm (0.0012 - 0.0028 inch)
No. 2 0.02 - 0.06 mm (0.0008 - 0.0024 inch)
Limit:
0.1 mm (0.004 inch)
3. Insert the piston ring into the cylinder bore. Force the ring down with a piston, the piston crown being in contact with the ring, to correctly position it at right angles to the cylinder wall. Then, measure the end gap with a feeler gauge.
If the ring gap is excessive, replace the piston ring.
Standard value:
No. 1: 0.30 - 0.45 mm (0.0118 - 0.0177 inch)
No. 2: 0.45 - 0.60 mm (0.0177 - 0.0236 inch)
Oil: 0.20 - 0.60 mm (0.0079 - 0.0236 inch)
Limit:
No. 1, No. 2: 0.8 mm (0.031 inch)
Oil: 1.0 mm (0.039 inch)
Crankshaft Pin Oil Clearance (Plastigauge Method)
The crankshaft oil clearance can be measured easily by using Plastigauge, as follows:
1. Remove oil and grease and any other foreign matters from the crankshaft pin and the bearing inner surface.
2. Install the crankshaft.
3. Cut Plastigauge to the same length as the width of the bearing and place it on the pin in parallel with its axis.
4. Gently place the crankshaft bearing cap over it and tighten the bolts to the specified torque.
5. Remove the bolts and gently remove the crankshaft bearing cap.
6. Measure the width of the crushed Plastigauge at its widest section by using a scale printed on the Plastigage bag.
Standard value: 0.02 - 0.05 mm (0.0008 - 0.0020 inch)
Limit: 0.1 mm (0.004 inch)
Installation
Installation in reverse order as removal.
Installation Service Points
]A[ Piston Pin Installation.
1. Heat the piston to approximately 70° C (158° F) and set the snap ring on one side first. Be sure to install the snap ring with the shear droop directed toward the inside.
2. With the front mark of the connecting rod and that of the piston located on the same side, insert the piston pin.
3. After insertion of the piston pin, set the other snap ring.
CAUTION: Apply an ample coat of engine oil to the periphery of the piston pin and the hole of the connecting rod small end.
The clearance between the piston and the piston pin is an almost tight fit at normal temperature. Therefore, be sure to heat the piston before inserting the piston pin.
In addition, note that the piston is hot after heating.
]B[ Oil Ring Installation.
1. Fit the oil ring spacer into the piston ring groove.
NOTE: The side rails and spacer may be installed in either direction.
2. Install the upper side rail
To install the side rail, first fit one end of the rail into the piston groove, then press the remaining portion into the position by finger. See illustration.
Use of a ring expander to expand the side rail end gap can break the side rail, unlike other piston rings.
NOTE: Do not use any piston ring expander when installing the side rail.
3. Install the lower side rail in the same procedure as described in step (2).
4. Make sure that the side rails move smoothly in either direction.
]C[ Piston Ring No.2 /Piston Ring No.1 Installation.
1. Using a piston ring expander, fit No.2 and then No.1 piston ring into position.
NOTE:
1. The ring end is provided with the identification mark.
2. Install piston rings with identification mark facing up, to the piston crown side.
]D[ Piston And Connecting Rod Installation.
1. Liberally coat the circumference of the piston, piston ring, and oil ring with engine oil.
2. Arrange the piston ring and oil ring gaps (side rail and spacer) as shown in the illustration.
3. Rotate the crankshaft so that the crank pin is on the center of the cylinder bore.
4. Use suitable thread protectors on the connecting rod bolts before inserting the piston and connecting rod assembly into the cylinder block.
Care must be taken not to nick the crank pin.
5. Using a suitable piston ring compressor tool, install the piston and connecting rod assembly into the cylinder block.
CAUTION: Install the piston with the front mark (arrow mark) on the top of the piston directed towards the engine front (timing belt side).
]E[ Connecting Rod Cap Installation.
1. Mate the correct bearing cap with the correct connecting rod by checking with the alignment marks marked during disassembly. If a new connecting rod is used which has no alignment mark, position the notches for locking the bearing on the same side.
2. Check if the thrust clearance in the connecting rod big end is correct.
Standard value: 0.10 - 0.25 mm (0.0039 - 0.0098 inch)
Limit: 0.4 mm (0.016 inch)
CRANKSHAFT AND DRIVE PLATE
Removal
Follow removal steps outlined in illustration.
Inspection
Crankshaft
If the oil clearance exceeds the limit, replace the bearing, and crankshaft if necessary.
1. Measure the outside diameter of the journals and the inside diameter of the crankshaft bearings. If the difference between them (oil clearance) exceeds the limit, replace the crankshaft bearing and, if necessary, crankshaft.
Standard value: 0.02 - 0.04 mm (0.0008 - 0.0020 inch)
Limit: 0.1 mm (0.004 inch)
CAUTION: Do not attempt an undersize machining of the and crankshaft if necessary.
Crankshaft Journal Oil Clearance
The crankshaft oil clearance can be measured easily by using Plastigauge, as follows:
1. Remove oil and grease and any other foreign matters from the crankshaft journal and bearing inner surface.
2. Install the crankshaft.
3. Cut Plastigauge to the same length as the width of the bearing and place it on the journal in parallel with its axis.
4. Gently place the crankshaft bearing cap over it and tighten the bolts to the specified torque.
5. Remove the bolts and gently remove the crankshaft bearing cap.
6. Measure the width of the crushed Plastigauge at its widest section by using a scale printed on the Plastigauge package.
Cylinder Block
1. Visually check for scratches, rust, and corrosion. Also use a flaw detecting agent for the check. If defects are evident, correct, or replace.
2. Using a straightedge and feeler gauge, check the flatness of the block top surface. Make sure that the surface is free from gasket pieces and other foreign matter.
Standard value: 0.05 mm (0.002 inch)
Limit: 0.1 mm (0.004 inch)
3. If distortion is excessive, correct within the allowable limit or replace.
Grinding limit:
0.2 mm (0.008 inch)
*Includes/combined with cylinder head grinding.
Cylinder block height (when new):
210.4 - 210.6 mm (8.283 - 8.291 inch)
4. Check the cylinder walls for scratches and seizure. If defects are evident, correct (rebore to an oversize) or replace.
5. Using a cylinder gauge, measure the cylinder bore and cylindricity. If worn badly, correct by boring the cylinders to an oversize and replace pistons and piston rings. Measure at the points shown in the illustration.
Standard value:
Cylinder l.D.: 93.0 mm (3.65 inch)
Cylindricity: 0.01 mm (0.0004 inch)
Boring Cylinder
1. Oversize pistons to be used should be determined on the basis of the largest bore cylinder.
Piston size identification
NOTE: Size mark is stamped on the piston top.
2. Measure the outside diameter of the piston to be used. Measure it in the thrust direction as shown.
3. Based on the measured piston O.D., calculate the boring finish dimension.
Boring finish dimension =
Piston O.D. + (clearance between piston O.D. and cylinder) - 0.02 mm (0.0008 inch) (honing margin)
4. Bore all cylinders to the calculated boring finish dimension.
CAUTION: To prevent distortion that may result from temperature rise during honing, bore cylinders in the order of No.2, No.4, No.6, No.1, No.3 and No.5.
5. Hone to the final finish dimension (piston O.D. + clearance between piston O.D. and cylinder).
6. Check the clearance between the piston and cylinder.
Clearance between piston and cylinder:
0.02 - 0.04 mm (0.0008 - 0.0016 inch)
NOTE: When boring cylinders, finish all of six cylinders to the same oversize. Do not bore only one cylinder to an oversize.
Installation
Installation in reverse order as removal.
Installation Service Points
]A[ Crankshaft Bearing Installation.
When the bearing needs replacing, select and install a proper bearing by the following procedure.
1. Measure the crankshaft journal diameter and confirm its classification from the following table. In the case of a bearing supplied as a service part, its identification color is painted at the position shown in the illustration.
2. The cylinder block bearing bore diameter identification marks are stamped at the position shown in the illustration from the front of the engine, beginning at No 1.
3. Select a proper bearing from the above table on the basis of the identification data confirmed under Items (1) and (2).
[Example]
(1) If the measured value of a crankshaft journal outer diameter is 59.996 mm (2.3620 inch), the journal is classified as "1" in the table. (In case the crankshaft is also replaced by a spare part, check the identification color painted on the new crankshaft. If it is yellow, for example, the journal is classified as u1 ,'.
(2) Next, check the cylinder block bearing hole identification mark stamped on the cylinder block. If it is "1", read the "Identification color for the spare bearing" column to find the identification color of the bearing to be used. In this case, it is "pink".
4. Install the bearing halves with oil groove in the cylinder block side.
5. Install the bearing halves without oil groove on the bearing cap side.
6. Install the thrust bearings on both sides of the No.3 bearing with the grooves facing outward.
Torque Sequence:
]B[ Bearing Cap/bearing Bolt Installation.
1. Attach the bearing cap on the cylinder block as shown in the illustration.
2. Tighten the bearing cap bolts to the specified torque in the sequence shown in the illustration.
3. Check that the crankshaft rotates smoothly.
4. Check the end plate. If it exceeds the limit value, replace the thrust bearing.
Standard value:
0.05 - 0.25 mm (0.0020 - 0.0098 inch)
Limit: 0.3 mm (0.012 inch)
]C[ Crankshaft Rear Oil Seal Installation.
Using the special tool, press-fit a new crankshaft rear oil seal into the oil seal case.
]D[ Oil Seal Case Installation.
1. Apply specified sealant to the area shown in the illustration.
Specified sealant:
MITSUBISHI GENUINE Part No. MD970389 or equivalent
2. Apply a small amount of engine oil to the entire circumference of the oil seal lip section, and place the oil seal on the cylinder block.