Piston, Connecting Rod and Cylinder Block

REMOVAL






1. Insert a 3/16 flat bladed screwdriver between the dust lip and the metal case of the crankshaft seal. Angle the screwdriver through the dust lip against metal case of the seal. Pry out seal.

CAUTION: Do not permit the screwdriver blade to contact crankshaft seal surface. Contact of the screwdriver blade against crankshaft edge (chamfer) is permitted.

2. Remove top ridge of cylinder bores with a reliable ridge reamer before removing pistons from cylinder block.
Be sure to keep tops of pistons covered during this operation. Mark piston with matching cylinder number.





3. Ensure connecting rods and connecting rod caps match and proper set for the cylinder number. Identify them if necessary.





4. Pistons and connecting rods must be removed from top of cylinder block. Rotate crankshaft so that each connecting rod is centered in cylinder bore.
5. Remove connecting rod cap bolts. Push each piston and rod assembly out of cylinder bore.
Be careful not to nick crankshaft journals.
6. After removal, install bearing cap in the connecting orientation on the mating connecting rod.

DISASSEMBLY
1. Separate piston from connecting rod by removing piston pin.





2. Using a suitable ring expander remove upper and intermediate piston rings.
3. Remove the upper oil ring side rail, lower oil ring side rail and then oil ring expander from piston.
4. Clean ring grooves of any carbon deposits.

REASSEMBLY





1. Install rings with manufacturer's I.D. mark facing up, toward the top of the piston.

CAUTION: Install piston rings in the following order:
a. Oil ring expander.
b. Upper oil ring side rail.
c. Lower oil ring side rail.
d. No. 2 intermediate piston ring.
e. No. 1 upper piston ring.

2. Install the side rail by placing one end between the piston ring groove and the expander. Hold end firmly and press down the portion to be installed until side rail is in position. Do not use a piston ring expander.
3. Install upper side rail first and then the lower side rail.





4. Install No. 2 piston ring and then No. 1 piston ring.





5. Position piston ring end gaps as shown in the figure.
6. Position oil ring expander gap at least 45 degrees from the side rail gaps but not on the piston pin center or on the thrust direction. Staggering ring gap is important for oil control.

INSTALLATION
1. Before installing pistons and connecting rod assemblies into the bore, be sure that compression ring gaps are staggered so that neither is in line with oil ring rail gap.





2. Before installing the ring compressor, make sure the oil ring expander ends are butted and the rail gaps located as shown in the figure.





3. Immerse the piston head and rings in clean engine oil, slide the ring compressor, over the piston. Be sure that position of rings does not change during this operation.





4. The arrow should face toward the front of the engine. Install the pistons.
5. Rotate crankshaft so that the connecting rod journal is on the center of the cylinder bore. Insert rod and piston assembly into cylinder bore and guide rod over the crankshaft journal.
6. Tap the piston down in cylinder bore, using a hammer handle. At the same time, guide connecting rod into position on connecting rod journal.





7. Install connecting rod bearings selected based on the obtained connecting rod bearing clearance.
8. Install each bolt finger tight then alternately torque each nut to assemble the cap properly.
9. Tighten the bolts to 27.0 Nm PLUS 1/4 turn (20 ft. lbs. PLUS 1/4 turn). Do not use a torque wrench for last step.





10. Using a feeler gauge, check connecting rod side clearance.
Standard value: 0.13 - 0.38 mm (0.005 - 0.015 inch)
Limit 0.37 mm (0.015 inch)

CAUTION: If burr or scratch is present on the crankshaft edge (chamfer), cleanup with 400 grit sand paper to prevent seal damage during installation of new seal.

NOTE: When installing seal, no lube on seal is needed.





11. Place Special Tool MB995059 on crankshaft. This is a pilot tool with a magnetic base.
12. Position seal over pilot tool. Make sure you can read the words THIS SIDE OUT on seal. Pilot tool should remain on crankshaft during installation of seal.








13. Drive the seal into the block using Special Tool MB995060 and handle C-4171 until the tool bottoms out against the block.

CAUTION: If the seal is driven into the block past flush, this may cause an oil leak.

INSPECTION

Cylinder Block
1. Clean cylinder block thoroughly and check all core hole plugs for evidence of leaking.
2. Examine block and cylinder bores for cracks or fractures.

Cylinder Bore
1. The cylinder walls should be checked for out-of-round and taper with Tool C-119 or equivalent. The cylinder bore out-of-round is 0.051 mm (0.002 inch) maximum and cylinder bore taper is 0.051 mm (0.002 inch) maximum. If the cylinder walls are badly scuffed or scored, the cylinder block should be rebored and honed, and new pistons and rings fitted. Whatever type of boring equipment is used, boring and honing should be closely coordinated with the fitting of pistons and rings so that specified clearances may be maintained.





2. Measure the cylinder bore at three levels in directions A and B. Top measurement should be 10 mm (0.39 inch) down and bottom measurement should be 10 mm (0.39 inch) up from bottom of bore.
Standard value: 87.5 mm (3.445 inch)

Pistons





1. Piston and cylinder wall must be clean and dry. Piston diameter should be measured 90 degrees to piston pin at size location shown in the figure. Cylinder bores should be measured halfway down the cylinder bore and transverse to the engine crankshaft center line. Correct piston to bore clearance must be established in order to assure quiet and economical operation.
Standard value: 0.012 - 0.044 mm (0.0005 - 0.0017 inch)
2. Pistons and cylinder bores should be measured at normal room temperature, 21°C (70°F).

Piston Ring





1. Wipe cylinder bore clean. Insert ring and push down with piston to ensure it is square in bore. The ring gap measurement must be made with the ring positioning at least 12 mm (0.47 inch) from bottom of cylinder bore. Check gap with feeler gauge.
Standard value:
Upper ring 0.23 - 0.52 mm (0.009 - 0.020 inch)
Intermediate ring 0.49 - 0.78 mm (0.019 - 0.031 inch)
Oil control ring 0.23 - 0.66 mm (0.009 - 0.026 inch)
Limit:
Upper ring 0.8 mm (0.031 inch)
Intermediate ring 1.0 mm (0.039 inch)
Oil control ring 1.0 mm (0.039 inch)





2. Check piston ring to groove side clearance.
Standard value: 0.025 - 0.065 mm (0.0010 - 0.0026 inch)
Limit: 0.10 mm (0.004 inch)

Crankshaft Main Bearings
The crankshaft is supported in five main bearings. All upper bearing shells in the crankcase have oil grooves. All lower bearing shells installed in the (bedplate) main bearing caps are plain. Crankshaft end play is controlled by a flanged bearing on the number three main bearing journal.

Connecting Rod Bearing Clearance
1. Place a piece of Plastigage across the entire width of the bearing shell in the bearing cap approximately 6.35 mm off center and away from the oil hole. In addition, suspect areas can be checked by placing Plastigage in the suspect area.
2. Before assembling the rod cap with Plastigage in place, the crankshaft must be rotated until the connecting rod being checked starts moving toward the top of the engine. Only then should the cap be assembled and torqued to the specification. Do not rotate the crankshaft while assembling the cap or the Plastigage may be smeared, giving inaccurate results.
3. Remove the bearing cap and compare the width of the flattened Plastigage with the metric scale provided on the package.
Standard value: 0.026 - 0.059 mm (0.001 - 0.0023 inch)
Limit: 0.075 mm (0.003 inch)

Connecting Rod Bearing Cap Bolt





1. Since the connecting rod bearing cap bolts are torqued using a new procedure, they should be examined BEFORE reuse. If the threads are necked down, replace the bolts.
2. Necking can be checked by holding a scale or straight edge against the threads. If all the threads do not contact the scale, the bolt should be replaced.