Piston Ring: Service and Repair
Part 1 Of 2:
Part 2 Of 2:
Pistons, Piston Rings, Connecting Rods and Cylinders Removal and Installation
Removal
1) Remove engine assembly from vehicle.
2) Remove oil pump with oil pump strainer.
3) Remove cylinder head.
4) Mark cylinder number on all pistons, connecting rods and connecting rod caps.
5) Remove rod bearing caps.
6) Install guide hose (1) over threads of rod bolts.
This prevents damage to bearing journal and rod bolt threads when removing connecting rod.
7) Clean carbon from top of cylinder bore before removing piston from cylinder.
8) Push piston and connecting rod assembly out through the top of cylinder bore.
Installation
1) Apply engine oil to pistons, rings, cylinder walls, connecting rod bearings and crank pins.
NOTE: Do not apply oil between connecting rod and bearing or between bearing cap and bearing.
2) Install guide hoses (1) over connecting rod bolts. These guide hoses protect crank pin and threads of rod bolt from damage during installation of connecting rod and piston assembly.
3) When installing piston and connecting rod assembly into cylinder bore, point arrow mark (3) on piston head to crankshaft pulley side (1).
4) Install piston and connecting rod assembly into cylinder bore. Use special tool (Piston ring compressor) to compress rings. Guide connecting rod into place on crankshaft.
Using a hammer handle, tap piston head to install piston into bore. Hold ring compressor firmly against cylinder block until all piston rings have entered cylinder bore.
Special Tool
(A): 09916-77310
5) Install bearing cap:
Point arrow mark (1) on cap to crankshaft pulley side. Tighten cap nuts to specification.
Tightening torque
Connecting rod bearing cap nuts (a): 45 Nm (4.5 kgf-cm, 33.0 ft. lbs.)
6) Install cylinder head.
7) Install oil pan.
8) Install engine assembly to vehicle.
Pistons, Piston Rings, Connecting Rods and Cylinders
Disassembly and Assembly
Disassembly
1) Using piston ring expander, remove two compression rings (Top and 2nd) and oil ring from piston.
2) Remove piston pin from connecting rod.
^ Ease out piston pin circlips (1), as shown.
^ Force piston pin out.
Assembly
NOTE: Two sizes of piston are available as standard size spare part so as to ensure proper piston-to-cylinder clearance. When installing a standard size piston, make sure to match piston with cylinder as follows.
1) Each piston (1) has stamped number 1 or 2 as shown. It represents outer diameter of piston.
2) There are also painted color (3) of red and blue on cylinder block (2) as shown.
3) Stamped number on piston and stamped mark on cylinder block should correspond. That is, install number 2 stamped piston to cylinder which is identified with mark blue and a number 1 piston to cylinder with mark red.
Piston and cylinder specifications
Also, a letter A, B or C is stamped on piston head but ordinarily it is not necessary to discriminate each piston by this letter.
4) Install piston pin to piston (1) and connecting rod (3):
After applying engine oil to piston pin and piston pin holes in piston and connecting rod, fit connecting rod to piston as shown in figure and insert piston pin to piston and connecting rod, and install piston pin circlips.
NOTE: "86F" mark on connecting rod should come on crankshaft pulley side.
NOTE: Circlip (4) should be installed so that circlip end gap comes within such range as indicated by arrow.
5) Install piston rings to piston:
^ As indicated in figure at the left, 1st and 2nd rings have "RN" or "R" mark respectively. When installing these piston rings to piston, direct marked side of each ring toward top of piston.
^ 1st ring (1) differs from 2nd ring (2) in thickness, shape and color of surface contacting cylinder wall.
Distinguish 1st ring from 2nd ring.
^ When installing oil ring (3), install spacer first and then two rails.
6) After installing three rings (1st, 2nd and oil rings), distribute their end gaps as shown in figure.
Pistons, Piston Rings, Connecting Rods and Cylinders Inspection and Cleaning
Clean carbon from piston head and ring grooves, using a suitable tool.
Cylinder
^ Inspect cylinder walls for scratches, roughness, or ridges which indicate excessive wear. If cylinder bore is very rough or deeply scratched, or ridged, rebore cylinder and use over size piston.
^ Using a cylinder gauge, measure cylinder bore in thrust and axial directions at two positions as shown in figure. If any of conditions is noted, rebore cylinder.
1) Cylinder bore diameter exceeds limit.
2) Difference of measurements at two positions exceeds taper limit.
3) Difference between thrust and axial measurements exceeds out-of-round limit.
Cylinder bore diameter limit: 84.050 mm (3.3090 inch)
Taper and out-of-round limit: 0.10 mm (0.004 inch)
NOTE: If any one of four cylinders has to be rebored, rebore all four to the same next oversize. This is necessary for the sake of uniformity and balance.
Pistons
^ Inspect piston for faults, cracks or other damages.
Damaged or faulty piston should be replaced.
^ Piston diameter:
As indicated in figure, piston diameter should be measured at a position 26.5 mm (1.04 inch) ("a") from piston skirt end in the direction perpendicular to piston pin.
Piston diameter
Standard 83.970 - 83.990 mm (3.3059 - 3.3066 inch)
Oversize: 0.50 mm (0.0196 inch): 84.470 - 84.490 mm (3.3256 - 3.3263 inch)
^ Piston clearance:
Measure cylinder bore diameter and piston diameter to find their difference which is piston clearance. Piston clearance should be within specification as follows. If it is out of specification, rebore cylinder and use oversize piston.
Piston clearance: 0.02 - 0.04 mm (0.0008 - 0.0015 inch)
NOTE: Cylinder bore diameters used here are measured in thrust direction at two positions.
^ Ring groove clearance:
Before checking, piston grooves must be clean, dry and free of carbon.
Fit new piston ring (1) into piston groove, and measure clearance between ring and ring land by using thickness gauge (2).
If clearance is out of specification, replace piston.
Ring groove clearance
Top: 0.03 - 0.07 mm (0.0012 - 0.0027 inch)
2nd: 0.02 - 0.06 mm (0.0008 - 0.0023 inch)
Piston Pin
^ Check piston pin, connecting rod small end bore and piston bore for wear or damage, paying particular attention to condition of small end bore bush. If pin, connecting rod small end bore or piston bore is badly worn or damaged, replace pin, connecting rod or piston.
^ Piston pin clearance: Check piston pin clearance in small end.
Replace connecting rod if its small end is badly worn or damaged or if measured clearance exceeds limit.
Piston pin clearance in small end (standard): 0.003 - 0.014 mm (0.0001 - 0.0005 inch)
Small-end bore: 21.003 - 21.011 mm (0.8269 - 0.8272 inch)
Piston pin diameter: 20.997 - 21.000 mm (0.8267 - 0.8268 inch)
Piston Rings
To measure end gap, insert piston ring (2) into cylinder bore and then measure the gap by using thickness gauge (1). If measured gap is out of specification, replace ring.
NOTE: Clean carbon and any other dirt from top of cylinder bore before inserting piston ring.
Piston ring end gap
Top ring
Standard 0.20 - 0.35 mm (0.0079 - 0.0137 inch)
Limit 0.7 mm (0.0276 inch)
2nd ring
Standard 0.35 - 0.50 mm (0.0138 - 0.0196 inch)
Limit 0.7 mm (0.0276 inch)
Oil ring
Standard 0.20 - 0.70 mm (0.0079 - 0.0275 inch)
Limit 1.8 mm (0.0709 inch)
Piston rings end gap
"a": 120 mm (4.72 inch)
Connecting Rod
^ Big-end side clearance:
Check big-end of connecting rod for side clearance, with rod fitted and connected to its crank pin in the normal manner. If measured clearance is found to exceed its limit, replace connecting rod.
Big-end side clearance
Standard: 0.25 - 0.40 mm (0.0099 - 0.0150 inch)
Limit:0.45 mm (0.0177 inch)
^ Connecting rod alignment:
Mount connecting rod on aligner to check it for bow and twist. If limit is exceeded, replace it.
Limit on bow 0.05 mm (0.0020 inch)
Limit on twist 0.10 mm (0.0039 inch)
Crank Pin And Connecting Rod Bearings
^ Inspect crank pin for uneven wear or damage. Measure crank pin for out-of-round or taper with a micrometer. If crank pin is damaged, or out-of round or taper is out of limit, replace crankshaft or regrind crank pin.
Connecting rod bearing and crank pin
Standard: 49.982 - 50.000 mm (1.9768 - 1.9685 inch)
0.25 mm (0.0098 inch) undersize: 49.732 - 49.750 mm (1.9580 - 1.9586 inch)
Out-of-round "A"-"B"
Taper "a"-"b"
Out-of-round and taper limits 0.01 mm (0.0004 inch)
^ Connecting rod bearing general information:
Service connecting rod bearings are available in standard size and 0.25 mm (0.0098 inch) undersize, and standard size bearing has 5 kinds of bearings differing in tolerance. For identification of undersize bearing, it is painted red at the position as indicated in the figure, undersize bearing thickness is 1.605 - 1.615 mm (0.0632 - 0.0635 inch) at the center of it.
^ Connecting rod bearing visual inspection:
Inspect bearing shells for signs of fusion, pitting, burn or flaking and observe contact pattern. Bearing shells found in defective condition must be replaced.
^ Connecting rod bearing clearance:
a. Before checking bearing clearance, clean bearing and crank pin.
b. Install bearing in connecting rod and bearing cap.
c. Place a piece of gauging plastic (1) to full width of crank pin as contacted by bearing (parallel to crankshaft), avoiding oil hole.
d. Install rod bearing cap to connecting rod. When installing cap, be sure to point arrow mark (1) on cap to crankshaft pulley side, as shown in the figure. After applying engine oil to rod bolts, tighten cap nuts to specified torque.
Tightening torque
Connecting rod bearing cap nuts (a): 45 Nm (4.5 kgf-cm, 33.0 ft. lbs.)
NOTE: DO NOT turn crankshaft with gauging plastic installed.
e. Remove cap and using a scale (2) on gauging plastic envelope, measure gauging plastic (1) width at the widest point (clearance).
If clearance exceeds its limit, use a new standard size bearing.
After selecting new bearing, recheck clearance.
Connecting rod bearing clearance
Standard: 0.045 - 0.063 mm (0.0018 - 0.0024 inch)
Limit: 0.08 mm (0.0031 inch)
f. If clearance can not be brought to within its limit even by using a new standard size bearing, replace crankshaft or regrind crankpin to undersize as follows.
^ Install 0.25 mm undersize bearing to connecting rod big end.
^ Measure bore diameter of connecting rod big end.
^ Regrind crankpin to the finished diameter.
Finished crankpin diameter = Measured big end bore diameter (including undersize bearing - 0.054 mm (0.0021 inch)
^ Confirm that bearing clearance is within the standard value.
Selection of connecting rod bearings
NOTE:
^ If bearing is in malcondition, or bearing clearance is out of specification, select a new standard bearing and install it.
^ When replacing crankshaft or connecting rod and its bearing due to any reason, select new standard bearings to be installed by referring to numbers stamped on connecting rod and its cap and/or alphabets stamped on crank web of No. 3 cylinder.
1) Check stamped numbers on connecting rod and its cap as shown.
Three kinds of numbers ("1", "2" and "3") represent the connecting rod big end inside diameters.
For example, stamped number"1" indicates that corresponding connecting rod big-end inside diameter is 53.0000 - 53.0060 mm (2.0867 - 2.0868 inch).
Connecting rod big-end inside diameter
Stamped numbers Connecting rod big-end inside diameter
1: 53.0000 - 53.0060 mm (2.0867 - 2.0868 inch)
2: 53.0061 - 53.0120 mm (2.0869 - 2.0870 inch)
3: 53.0121 - 53.0180 mm (2.0871 - 2.0873 inch)
2) Next, check crank pin diameter. On crank web of No. 3 cylinder, four alphabets are stamped as shown in the figure.
Three kinds of alphabet ("A", "B" and "C") represent the crank pin diameter respectively.
For example, stamped "A" indicates that corresponding crank pin diameter is 49.9940 - 50.0000 mm (1.9683 - 1.9685 inch).
Crank pin diameter
Stamped alphabet Crank pin diameter (without bearing)
A: 49.9940 - 50.0000 mm (1.9683 - 1.9685 inch)
B: 49.9880 - 49.9939 mm (1.9681 - 1.9682 inch)
C: 49.9820 - 49.9879 mm (1.9677 - 1.9680 inch)
3) There are 5 kinds of standard bearings differing in thickness. To distinguish them, they are painted in the colors at the position as indicated in the figure.
Each color indicated the thickness at the center of bearing.
Standard size of connecting rod bearing thickness
Color painted Bearing thickness
Blue: 1.494 - 1.497 mm (0.05882 - 0.05893 inch)
Yellow: 1.491 - 1.494 mm (0.05871 - 0.05881 inch)
Nothing: 1.488 - 1.491 mm (0.05859 - 0.05870 inch)
Black: 1.485 - 1.488 mm (0.05847 - 0.05858 inch)
Green: 1.482 - 1.485 mm (0.05835 - 0.05846 inch)
4) From number stamped on connecting rod and its cap and alphabet stamped on crank web No. 3 cylinder, determine new standard bearing to be installed to connecting rod big-end inside.
For example, if number stamped on connecting rod and its cap is "1" and alphabet stamped on crank web No. 3 cylinder is "B", install a new standard bearing painted in "Black" to its connecting rod big-end inside.
Specifications of new standard connecting rod bearing size
Alphabet stamped on crank web of No.3 cylinder (Crank pin diameter)
Number stamped on connecting rod and its cap (Connecting rod big end inside diameter)
A
1 Green
2 Black
3 Nothing
B
1 Black
2 Nothing
3 Yellow
C
1 Nothing
2 Yellow
3 Blue
New standard bearing to be installed.
5) Check bearing clearance with newly selected standard bearing. If clearance still exceeds its limit, use next thicker bearing and recheck clearance.