1. Check for cracks or damage. Use liquid penetrant tester on the important sections to check for fissures. Check that there are no marks of gas leaking or water leaking on gasket installing surface.
2. Check the oil passages for clogging.
3. Inspect the cylinder head to cylinder block mating surface for warpage by using a straight edge, and correct by grinding if necessary.
Warping limit:
0.025 mm (0.00098 in)
Grinding limit:
0.1 mm (0.004 in)
Standard height of cylinder block:
201.0 mm (7.91 in)
1. The cylinder bore size is stamped on the front upper face of the cylinder block.
NOTE:
• Measurement should be performed at a temperature of 20°C (68°F).
• Standard sized pistons are classified into two grades, “A” and “B”. These grades should be used as guide lines in selecting a standard piston.
Standard diameter:
A: 99.505 — 99.515 mm (3.9175 — 3.9179 in)
B: 99.495 — 99.505 mm (3.9171 — 3.9175 in)
|
(A) |
Main journal size mark |
|
(B) |
Cylinder block (RH) — (LH) combination mark |
|
(C) |
#1 cylinder bore size mark |
|
(D) |
#2 cylinder bore size mark |
|
(E) |
#3 cylinder bore size mark |
|
(F) |
#4 cylinder bore size mark |
2. Measure the inner diameters of the cylinders.
Measure the inner diameter of each cylinder in both the thrust and piston pin directions at the heights as shown in the figure, using a cylinder bore gauge.
NOTE:
Measurement should be performed at a temperature of 20°C (68°F).
Taper:
Standard:
0.015 mm (0.0006 in)
Out-of-roundness:
Standard:
0.010 mm (0.0004 in)
|
(A) |
Piston pin direction |
|
(B) |
Thrust direction |
|
H1 |
10 mm (0.39 in) |
|
H2 |
45 mm (1.77 in) |
|
H3 |
80 mm (3.15 in) |
|
H4 |
115 mm (4.53 in) |
3. When the piston is to be replaced due to general or cylinder wear, select a suitable sized piston by measuring the piston clearance.
4. Measure the outer diameters of the piston.
Measure the outer diameter of each piston at the height as shown in the figure. (Thrust direction)
NOTE:
Measurement should be performed at a temperature of 20°C (68°F).
Piston grade point H:
38.2 mm (1.504 in)
Piston outer diameter:
Standard
A: 99.505 — 99.515 mm (3.9175 — 3.9179 in)
B: 99.495 — 99.505 mm (3.9171 — 3.9175 in)
0.25 mm (0.0098 in) oversize:
99.745 — 99.765 mm (3.9270 — 3.9277 in)
0.50 mm (0.0197 in) oversize:
99.995 — 100.015 mm (3.9368 — 3.9376 in)
5. Calculate the clearance between cylinder and piston.
NOTE:
Measurement should be performed at a temperature of 20°C (68°F).
Cylinder to piston clearance at 20°C (68°F):
Standard:
−0.010 — 0.010 mm (−0.00039 — 0.00039 in)
6. Boring and honing
(1) If any of the measured value of taper, out-of-roundness or cylinder-to-piston clearance is out of standard or if there is any damage on the cylinder wall, rebore it to replace with an oversize piston.
CAUTION:
When any of the cylinders needs reboring, other cylinders must be bored at the same time, and replaced with oversize pistons.
(2) If the cylinder inner diameter exceeds the limit after boring and honing, replace the cylinder block.
NOTE:
Immediately after reboring, the cylinder diameter may differ from its real diameter due to temperature rise. Thus, when measuring the cylinder diameter, wait until it has cooled to room temperature.
Cylinder inner diameter boring limit (diameter):
To 100.005 mm (3.9372 in)
1. Check the piston and piston pin for breaks, cracks or wear. Replace if faulty.
2. Check the piston ring groove for wear and damage. Replace if faulty.
3. Make sure that the piston pin can be inserted into the piston pin hole with a thumb at 20°C (68°F). Replace if faulty.
Clearance between piston hole and piston pin:
Standard
0.004 — 0.008 mm (0.0002 — 0.0003 in)
4. Check the snap ring installation groove (A) on the piston for burr. If necessary, remove burr from the groove so that the piston pin can lightly move.
5. Check the piston pin snap ring for distortion, cracks and wear.
1. If the piston ring is broken, damaged, worn, its tension is insufficient, or when replacing the piston, replace with a new piston ring of the same size as the piston.
NOTE:
• The top ring and second ring have the mark to determine the direction to install on them. When installing the ring to piston, face this mark to the top side.
• Oil ring consists of the upper rail, expander and lower rail. Be careful about the direction of rail when installing the oil ring to piston.
|
(A) |
Upper rail |
|
(B) |
Expander |
|
(C) |
Lower rail |
2. Squarely place the piston ring and oil ring in cylinder using the piston, and measure the piston ring gap with a thickness gauge.
|
Standard mm (in) | |||
|
Piston ring gap |
Top ring |
0.20 — 0.35 (0.0079 — 0.0138) | |
|
Second ring |
0.37 — 0.52 (0.0146 — 0.0205) | ||
|
Oil ring rail |
0.20 — 0.50 (0.0079 — 0.0197) | ||
3. Fit the piston ring straight into the piston ring groove, then measure the clearance between piston ring and piston ring groove with a thickness gauge.
NOTE:
Before measuring the clearance, clean the piston ring groove and piston ring.
|
Standard mm (in) | |||
|
Clearance between piston ring and piston ring groove |
Top ring |
0.040 — 0.080 (0.0016 — 0.0031) | |
|
Second ring |
0.030 — 0.070 (0.0012 — 0.0028) | ||
1. Replace the connecting rod, if the large or small end thrust surface is damaged.
2. Check for bend or twist using a connecting rod aligner. Replace the connecting rod if the bend or twist exceeds the limit.
Limit of bend or twist per 100 mm (3.94 in) in length:
0.10 mm (0.0039 in)
|
(A) |
Thickness gauge |
|
(B) |
Connecting rod |
3. Install the connecting rod fitted with bearing to the crankshaft, and measure the thrust clearance using a thickness gauge. If the thrust clearance exceeds the standard or uneven wear is found, replace the connecting rod.
Connecting rod thrust clearance:
Standard
0.070 — 0.330 mm (0.0028 — 0.0130 in)
4. Inspect the connecting rod bearing for scar, peeling, seizure, melting, wear, etc.
5. Measure the oil clearance on each connecting rod bearing using plastigauge. If any oil clearance is not within the standard, replace the defective bearing with a new part of standard size or undersize as necessary.
Connecting rod oil clearance:
Standard
0.016 — 0.044 mm (0.0006 — 0.0017 in)
|
Unit: mm (in) | ||
|
Bearing |
Bearing size (Thickness at center) |
Outer diameter of crank pin |
|
Standard |
1.492 — 1.501 (0.0587 — 0.0591) |
51.984 — 52.000 (2.0466 — 2.0472) |
|
0.03 (0.0012) Undersize |
1.510 — 1.513 (0.0594 — 0.0596) |
51.954 — 51.970 (2.0454 — 2.0461) |
|
0.05 (0.0020) Undersize |
1.520 — 1.523 (0.0598 — 0.0600) |
51.934 — 51.950 (2.0446 — 2.0453) |
|
0.25 (0.0098) Undersize |
1.620 — 1.623 (0.0638 — 0.0639) |
51.734 — 51.750 (2.0368 — 2.0374) |
6. Inspect the bushing at connecting rod small end, and replace with a new part if worn or damaged.
7. Measure the piston pin clearance at connecting rod small end. If the measured value is not within the standard, replace it with a new part.
Clearance between piston pin and bushing:
Standard
0 — 0.022 mm (0 — 0.0009 in)
8. The replacement procedure for the connecting rod small end bushing is as follows.
(1) Remove the bushing from connecting rod with ST and press.
(2) Press the bushing with the ST after applying oil on the periphery of new bushing.
| ST 499037100 | CONNECTING ROD BUSHING REMOVER AND INSTALLER |
(3) Make two 3 mm (0.12 in) holes in the pressed bushing by aligning with the pre-manufactured holes on the connecting rod, and ream the inside of the bushing.
(4) After completion of reaming, clean the bushing to remove chips.
6. CRANKSHAFT AND CRANKSHAFT BEARING
1. Clean the crankshaft completely, and check it for cracks using liquid penetrant tester. If defective, replace the crankshaft.
2. Measure the bend of crankshaft. If it exceeds the limit, correct or replace it.
NOTE:
If a suitable V-block is not available, using just the #1 and #5 crankshaft bearings on cylinder block, position the crankshaft on cylinder block. Then, measure the crankshaft bend using a dial gauge.
Crankshaft bend limit:
0.035 mm (0.0014 in)
3. Inspect the crank journal and crank pin for wear. If they are not within the specification, replace the bearing with a suitable (undersize) one, and replace or grind to correct the crankshaft as necessary. When grinding the crank journal or crank pin, finish them to the specified dimensions according to the undersize bearing to be used.
Crank pin:
Out-of-roundness
0.003 mm (0.0001 in)
Cylindricality
0.004 mm (0.0002 in)
Grinding limit (dia.)
To 51.750 mm (2.0374 in)
Crank journal:
Out-of-roundness
0.005 mm (0.0002 in)
Cylindricality
0.006 mm (0.0002 in)
Grinding limit (dia.)
To 59.758 mm (2.3527 in)
|
Unit: mm (in) | ||||
|
Crank journal outer diameter |
Crank pin outer diameter | |||
|
#1, #3 |
#2, #4, #5 | |||
|
Standard |
Journal O.D. |
59.992 — 60.008 (2.3619 — 2.3625) |
59.992 — 60.008 (2.3619 — 2.3625) |
51.984 — 52.000 (2.0466 — 2.0472) |
|
Bearing size (Thickness at center) |
1.998 — 2.011 (0.0787 — 0.0792) |
2.000 — 2.013 (0.0787 — 0.0793) |
1.492 — 1.501 (0.0587 — 0.0591) | |
|
0.03 (0.0012) Undersize |
Journal O.D. |
59.962 — 59.978 (2.3607 — 2.3613) |
59.962 — 59.978 (2.3607 — 2.3613) |
51.954 — 51.970 (2.0454 — 2.0461) |
|
Bearing size (Thickness at center) |
2.017 — 2.020 (0.0794 — 0.0795) |
2.019 — 2.022 (0.0795 — 0.0796) |
1.510 — 1.513 (0.0594 — 0.0596) | |
|
0.05 (0.0020) Undersize |
Journal O.D. |
59.942 — 59.958 (2.3599 — 2.3605) |
59.942 — 59.958 (2.3599 — 2.3605) |
51.934 — 51.950 (2.0446 — 2.0453) |
|
Bearing size (Thickness at center) |
2.027 — 2.030 (0.0798 — 0.0799) |
2.029 — 2.032 (0.0799 — 0.0800) |
1.520 — 1.523 (0.0598 — 0.0600) | |
|
0.25 (0.0098) Undersize |
Journal O.D. |
59.742 — 59.758 (2.3520 — 2.3527) |
59.742 — 59.758 (2.3520 — 2.3527) |
51.734 — 51.750 (2.0368 — 2.0374) |
|
Bearing size (Thickness at center) |
2.127 — 2.130 (0.0837 — 0.0839) |
2.129 — 2.132 (0.0838 — 0.0839) |
1.620 — 1.623 (0.0638 — 0.0639) | |
4. Use a thickness gauge to measure the thrust clearance of the crankshaft at the #5 crank journal bearing. If the thrust clearance is not within the standard, replace the bearing.
Crankshaft thrust clearance:
Standard
0.030 — 0.115 mm (0.0012 — 0.0045 in)
5. Inspect individual crankshaft bearings for signs of flaking, seizure, melting and wear.
6. Measure the oil clearance on each crankshaft bearing using plastigauge. If the measured value is out of standard, replace the defective bearing with an undersize one, and replace or grind to correct the crankshaft as necessary.
Crankshaft oil clearance:
Standard
0.010 — 0.030 mm (0.0004 — 0.0012 in)