Connecting Rod: Service and Repair
ROD-PISTON & CONNECTINGCONNECTING ROD BEARING FITTING
Inspect the connecting rod bearings for scoring (1) and (3). Check the bearings for normal wear patterns, scoring, grooving, fatigue and pitting. Replace any bearing that shows abnormal wear.
Inspect the connecting rod journals for signs of scoring, nicks and burrs.
Misaligned or bent connecting rods can cause abnormal wear on pistons, piston rings, cylinder walls, connecting rod bearings and crankshaft connecting rod journals. If wear patterns or damage to any of these components indicate the probability of a misaligned connecting rod, inspect it for correct rod alignment. Replace misaligned, bent or twisted connecting rods.
1. Wipe the oil from the connecting rod journal.
2. Lubricate the upper bearing insert (2) and position in connecting rod (1). Center bearing insert in connecting rod
3. Measure at point A and point B. Measurement should be less then 0.50 mm (0.0196 in.).
4. Use piston ring compressor (3) and Guide Pins Special Tool 8507 (4) to install the rod and piston assemblies. The oil slinger slots in the rods must face front of the engine. The "F"'s (1) near the piston wrist pin bore should point to the front of the engine.
5. Install the lower bearing insert in the bearing cap. Center bearing insert in connecting rod. The lower insert must be dry. Place strip of Plastigage (1) across full width of the lower insert at the center of bearing cap. Plastigage must not crumble in use. If brittle, obtain fresh stock.
6. Install bearing cap and connecting rod on the journal and tighten bolts to 27 Nm (20 ft. lbs.) plus a 90° turn. DO NOT rotate crankshaft. Plastigage will smear, resulting in inaccurate indication.
7. Remove the bearing cap and determine amount of bearing-to-journal clearance by measuring the width of compressed Plastigage (2). Refer to Engine Specifications for the proper clearance. Plastigage should indicate the same clearance across the entire width of the insert. If the clearance varies, it may be caused by either a tapered journal, bent connecting rod or foreign material trapped between the insert and cap or rod.
8. If the correct clearance is indicated, replacement of the bearing inserts is not necessary. Remove the Plastigage from crankshaft journal and bearing insert. Proceed with installation.
9. If bearing-to-journal clearance exceeds the specification, determine which service bearing set to use the bearing sizes are as follows:
CAUTION
Connecting Rod Bolts are Torque to Yield Bolts and Must Not Be Reused. Always replace the Rod Bolts whenever they are loosened or removed.
10. Repeat the Plastigage measurement to verify your bearing selection prior to final assembly.
11. Once you have selected the proper insert, install the insert and cap. Tighten the connecting rod bolts to 27 Nm (20 ft. lbs.) plus a 90° turn.
Slide snug-fitting feeler gauge between the connecting rod and crankshaft journal flange. Refer to Engine Specifications for the proper clearance. Replace the connecting rod if the side clearance is not within specification.
PISTON FITTING
1. To correctly select the proper size piston, a cylinder bore gauge (2), capable of reading in 0.003 mm (0.0001 in.) INCREMENTS is required. If a bore gauge is not available, do not use an inside micrometer.
2. Measure the inside diameter of the cylinder bore at a point 38.0 mm (1.5 inches) below top of bore (4). Start perpendicular (across or at 90°) to the axis of the crankshaft at point A and then take an additional bore reading 90° to that at point B.
3. The coated pistons will be serviced with the piston pin and connecting rod pre-assembled.
4. The coating material (1) and (2) is applied to the piston after the final piston machining process. Measuring the outside diameter of a coated piston will not provide accurate results. Therefore measuring the inside diameter of the cylinder bore with a dial Bore Gauge is MANDATORY. To correctly select the proper size piston, a cylinder bore gauge capable of reading in 0.003 mm (0.0001 in.) increments is required.
5. Piston installation into the cylinder bore requires slightly more pressure than that required for non-coated pistons. The bonded coating on the piston will give the appearance of a line-to-line fit with the cylinder bore.
REMOVAL
1. Disconnect the negative cable from battery.
2. Remove the following components:
^ Oil pan and gasket/windage tray.
^ Cylinder head(s).
3. If necessary, 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. Pistons and connecting rods must be removed from top of cylinder block. When removing piston and connecting rod assemblies from the engine, rotate crankshaft so that each connecting rod is centered in cylinder bore.
CAUTION
DO NOT use a number stamp or a punch to mark connecting rods or caps, as damage to connecting rods could occur
NOTE: Connecting rods and bearing caps are not interchangeable and should be marked before removing to ensure correct reassembly.
4. Mark connecting rod and bearing cap positions using a permanent ink marker or scribe tool.
CAUTION
Care must be taken not to damage the fractured rod and cap joint face surfaces, as engine damage may occur.
5. Remove connecting rod cap. Install Connecting Rod Guides I 8507 onto the connecting rod being removed. Remove piston from cylinder bore. Repeat this procedure for each piston being removed.
CAUTION
Care must be taken not to nick crankshaft journals, as engine damage may occur
6. Immediately after piston and connecting rod removal, install bearing cap on the mating connecting rod to prevent damage to the fractured cap and rod surfaces.
CLEANING
CAUTION
DO NOT use a wire wheel or other abrasive cleaning devise to clean the pistons or connecting rods. The pistons have a Moly coating, this coating must not be damaged.
CAUTION
DO NOT remove the piston pin from the piston and connecting rod assembly.
1. Using a suitable cleaning solvent clean the pistons in warm water and towel dry.
2. Use a wood or plastic scraper to clean the ring land grooves.
INSPECTION
Check the connecting rod journal for excessive wear, taper and scoring.
Check the connecting rod for signs of twist or bending.
Check the piston for taper and out of round shape before it is fitted into the cylinder bore.
Check the piston for scoring, or scraping marks in the piston skirts. Check the ring lands for cracks and/or deterioration.
INSTALLATION
1. Before installing piston and connecting rod assemblies into the bore, install the piston rings.
2. Immerse the piston head and rings in clean engine oil. Position a ring compressor (3) over the piston and rings. Tighten ring compressor (3). Ensure position of rings did not change during this operation.
3. Position bearing onto connecting rod. Ensure that lubrication hole in bearing shell aligns with lubrication hole in the connecting rod. Lubricate bearing surface with clean engine oil.
4. Install Connecting Rod Guides 8507 (4) onto connecting rod bolt threads.
5. The pistons are marked on the piston pin bore surface with a raised "F" (1) indicating installation position. This mark must be pointing toward the front of engine on both cylinder banks. The connecting rod oil slinger slot faces the front of the engine.
6. Wipe cylinder bore clean and lubricate with clean engine oil.
7. Rotate crankshaft until connecting rod journal is on the center of cylinder bore. Insert rod and piston into cylinder bore and carefully position connecting rod guides over crankshaft journal.
8. Tap piston down in cylinder bore using a hammer handle. While at the same time, guiding the connecting rod into position over the rod journal.
CAUTION
Connecting Rod Bolts Must Not Be Reused. Always replace the Rod Bolts whenever they are loosened or removed.
9. Lubricate NEW rod bolts and bearing surfaces with engine oil. Install connecting rod cap and bearing. Tighten the NEW bolts to 27 Nm (20 ft. lbs.) plus 90°.
10. Install the following components:
^ Cylinder head(s).
^ Timing chain and cover.
^ Cylinder head covers.
^ Oil pan and gasket/windage tray.
11. Fill crankcase with proper engine oil to correct level.
12. Connect negative cable to battery.