REMOVAL & INSTALLATION
- Rod bearings can be installed when the pistons have been removed for servicing (rings etc.) or, in most cases, while the engine is still in the car. Bearing replacement, however, is far easier with the engine out of the car and disassembled.
- For in car service, perform the following:
- Remove the oil pan, spark plugs and front cover, if necessary. Turn the engine until the connecting rod to be serviced is at the bottom of its travel. Remove the bearing cap, place two pieces of rubber hose over the rod cap bolts and push the piston and rod assembly up the cylinder bore until enough room is gained for bearing insert removal. Take care not to push the rod assembly up too far or the top ring will engage the cylinder ridge or come out of the cylinder and require head removal for reinstallation.
- Clean the rod journal, the connecting rod end and the bearing cap after removing the old bearing inserts. Install the new inserts in the rod and bearing cap, lubricate them with oil. Position the rod over the crankshaft journal and install the rod cap. Make sure the cap and rod numbers match, tighten the rod nuts to specifications.
Main bearings may be replaced while the engine is still in the car by "rolling" them out and in.
- Special roll-out pins are available from automotive parts houses or can be fabricated from a cotter pin. The roll-out pin fits in the oil hole of the main bearing journal. When the crankshaft is rotated opposite the direction of the bearing locktab, the pin engages the end of the bearing and "rolls" out the insert.
- Remove the main bearing cap and roll out the upper bearing insert. Remove the insert from the main bearing cap. Clean the inside of the bearing cap and crankshaft journal.
- Lubricate and roll the upper insert into position, make sure the locktab is anchored and the insert is not cocked. Install the lower bearing insert into the cap, then lubricate the bearing and install it on the engine. Make sure the main bearing cap is installed facing in the correct direction and tighten the cap nuts to specifications.
- With the engine out of the car perform the following:
- Remove the intake manifold, cylinder heads, front cover, timing gears and/or chain, oil pan, oil pump and flywheel.
- Remove the piston and rod assemblies. Remove the main bearing caps after marking them for position and direction.
- Remove the crankshaft, bearing inserts and rear main oil seal. Clean the engine block and cap bearing saddles. Clean the crankshaft and inspect for wear. Check the bearing journals with a micrometer for out-of-round condition and to determine what size rod and main bearing inserts to install.
- Install the main bearing upper inserts and rear main oil seal half into the engine block.
- Lubricate the bearing inserts and the crankshaft journals. Slowly and carefully lower the crankshaft into position.
- Install the bearing inserts and rear main seal into the bearing caps, install the caps working from the middle out. Torque cap bolts to specifications in stages, rotate the crankshaft after each torque stage.
- Remove bearing caps, one at a time and check the oil clearance with Plastigage®. Reinstall if clearance is within specifications. Check the crankshaft end-play; if within specifications, install connecting rod and piston assemblies with new rod bearing inserts. Check connecting rod bearing oil clearance and rod side play; if correct, assemble the rest of the engine.
BEARING OIL CLEARANCE
Remove the cap from the journal to be checked. Using a clean, dry rag, thoroughly clean all oil from the crankshaft journal and the bearing insert.
Plastigage® is soluble in oil; therefore, oil on the journal or bearing could result in erroneous readings.
Place a piece of Plastigage® along the full width of the insert, reinstall cap, and tighten it to specifications.
Specifications are given in the engine specifications chart earlier in this section.
Remove the bearing cap, and determine the bearing clearance by comparing the width of the Plastigage® to the scale on the Plastigage® envelope. Journal taper is determined by comparing the width of the Plastigage® strip near its ends. Rotate the crankshaft 90° and retest, to determine journal eccentricity.
Do not rotate the crankshaft with Plastigage® installed. If the bearing insert and journal appear intact, and are within tolerances, no further main bearing service is required. If the bearing or journal appear defective, cause of failure should be determined before replacement.
CRANKSHAFT END-PLAY & CONNECTING ROD SIDE PLAY INSPECTION
Place a prybar between a main bearing cap and crankshaft casting, taking care not to damage any journals. Pry backward and forward and measure the distance between the thrust bearing (No. 3) and crankshaft with a feeler gauge. Compare the reading with specifications. If too great a clearance is determined, a main bearing with a larger thrust surface or crankshaft machining may be required. Check with an automotive machine shop for their advice.
Connecting rod clearance between the rod and crankshaft throw casting can be checked with a feeler gauge. Pry the rod carefully to one side as far as possible and measure the distance on the other side of the rod.
If a journal is damaged on the crankshaft, repair is possible by having the crankshaft machined to a standard undersize.
In most cases, however, since the crankshaft must be removed from the engine, some thought should be given to replacing the damaged crankshaft with a reground shaft kit. A reground crankshaft kit contains the necessary main and rod bearings for installation. The shaft has been ground and polished to undersize specifications and will usually hold up well if installed correctly.