Connecting Rod: Service and Repair
CONNECTING ROD
COMPONENT
DISASSEMBLY
1. Mark corresponding cylinder number on rod cap and connecting rod with a numbering stamp.
NOTE: Mark connecting rods on same side and make a reference mark on block so that rods are installed in correct position and direction. Failure to install rods properly with result in oil starvation, spun bearings, or damaged internal engine components.
2. Rotate crankshaft so that cylinders No.2 and No.3 are at Bottom Dead Center (BDC) and repeat marking procedure.
3. Remove connecting rod nuts and gently loosen rod caps by tapping cap with a light plastic mallet.
4. Remove rod caps.
NOTE: Coter connecting rod bolts to protect crankshaft journals
5. Push connecting rod and piston as far up into cylinder as possible. Using a wooden dowel, tap gently on piston to release it from cylinder.
6. Repeat this procedure for each cylinder.
7. Mark tops of pistons with corresponding cylinder numbers they were removed from.
8. Using a piston ring expander, remove piston rings.
9. Hold piston upright and gently move connecting rod.
10. Release connecting rod and observe its movement.
NOTE: Do not swing connecting rod widely. Constant, hard contact with piston will cause a bell-mouth condition that will require piston replacement.
11. If connecting rod does not move freely, check piston pin bore and connecting rod for straightness and deformation.
12. Remove piston pin clip from ends of piston pin bore.
13. Tilt piston and allow piston pin to slide out into your hand. Piston pins may need to be pressed out.
NOTE: Do not allow pins to drop to the ground.
14. Remove connecting rod from piston. Keep individual piston and piston pin together for reassembly.
INSPECTION
PISTON RING
1. Insert a new piston ring into a piston ring groove and check clearance between piston ring and ring end. Clearance between ring and ring end
2. If clearance exceeds the maximum, replace piston.
3. Inspect piston rings for damage, abnormal wear, or breakage.
4. Replace piston rings if necessary.
5. Insert piston ring into cylinder by hand.
6. Square ring in cylinder by inverting a piston into cylinder and pushing ring to the bottom of its travel in cylinder.
7. Place a feeler gauge in end gap and check end gap clearance.
END GAP CLEARANCE
REASSEMBLY
1. Select the piston which has the size mark which is identical with the size mark of the corresponding cylinder.
PISTON OUTER DIAMETER AND CYLINDER BORE INNER DIAMETER
2. Insert connecting rod into piston and slide piston pin through piston and connecting rod.
NOTE: Verify that piston and rod are assembled in same direction as they were prior to disassembly.
3. Hold piston upright and move connecting rod back and forth. Check that rod moves freely.
4. Install three piece oil ring onto piston.
1. Apply clean engine oil to the oil ring expander and upper and lower oil rings.
2. Install expander onto piston so that expander ends face upward.
3. Install lower oil ring onto piston. Ring may be installed with either face upward.
4. Install upper oil ring onto piston. Ring may be installed with either face upward.
5. Check that oil ring expander separates upper and lower oil rings, and that oil ring assembly spins freely on piston.
6. Use a ring expander and install second ring.
7. Use a ring expander and install top ring.
NOTE: Top ring and second ring should be installed with "R" or "Y" mark facing up.
8. Align piston ring gaps as shown.
9. Install a bearing into connecting rod.
10. Place rubber sleeves on connecting rod bolts to protect crankshaft from damage.
11. Check piston rings for correct end gap stagger.
12. Place piston with "F" mark facing front of engine block, then slip piston and connecting rod assembly into a piston ring compressor.
13. Rotate crankshaft so that crank pin journal for specific cylinder is at its lowest point (bottom dead center).
14. Lower piston and connecting rod assembly until piston ring compressor makes contact with deck surface of engine block.
15. Using butt end of a hammer, tap the top of piston into cylinder and continue tapping until connecting rod makes contact with crankshaft.
NOTE: Follow this procedure for remaining piston and connecting, rod assemblies.
16. Install a connecting rod bearing in each connecting rod cap.
17. Place a piece of Plastigauge(R) on crank pin journals.
18. Install connecting rod caps, aligning marks made previous to disassembly and torque to specification.
Tightening torque: 22 - 24 ft. lbs. (29 - 34 Nm, 3.0 - 3.5 kgf-cm)
NOTE:
^ When installing the connecting rods, match marks made on the connecting rod and cap to reference mark made on cylinder block to prevent oil starvation to the connecting rod bearings.
^ When installing the piston assembly into cylinder block, position the piston between TDC and BDC, then install the cylinder head in order to prevent pistons and valves from contacts which may cause damage.
19. Loosen and remove connecting rod caps.
20. Check the connecting rod bearing clearance.
21. If oil clearance exceeds maximum oil clearance specification, grind the crankshaft and use undersized connecting rod bearings.
1) Connecting rod bearing selection table
2) Connecting rod bearing housing bore size
3) Connecting rod bearing thickness
22. Apply a coat of clean engine oil to connecting rod bearing in connecting rod cap.
23. Install connecting rod cap and torque to specification.
Tightening torque: 22 - 24 ft. lbs. (29 - 34 Nm, 3.0 - 3.5 kgf-cm)
24. Insert a thickness gauge between connecting rod and crankshaft and check connecting rod side clearance.
NOTE: Do not measure between connecting rod cap and crankshaft.
Side clearance: 0.0044 - 0.0103 inch (0.110 - 0.262 mm)
Maximum: 0.012 inch (0.30 mm)
25. If side clearance exceeds maximum side clearance specification, replace connecting rod and cap.