REMOVAL & INSTALLATION
- For in car service, remove the oil pan, spark plugs and front cover if necessary. The main bearings may be replaced while the engine is still in the car by rolling them out and in.
Check the edges of the main bearing cap for numbers or matchmarks, if none are present mark the caps numerically and in sequence from front to back of engine. The numbers or marks not only tell from which journal the cap came, but also ensures that the caps are installed in the correct matching position.
- Turn the engine until the main bearing cap to be serviced is at the bottom of travel. Remove the bearing cap bolts and remove the cap.
- 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 lock tab, the pin engages the end of the bearing and rolls out the insert.
- Remove main bearing cap and roll out upper bearing insert. Remove insert from main bearing cap. Clean the inside of the bearing cap and crankshaft journal.
- Lubricate and roll upper insert into position, make sure the lock tab is anchored and the insert is not cocked. Install the lower bearing insert into the cap, lubricate and install on the engine. Make sure the main bearing cap is installed facing in the correct direction and torque to specifications.
- With the engine out of the car, 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 state.
On the 5M-GE and 7M-GE engines, install the thrust washers on the number 4 bearing cap with the oil grooves facing outward. On the 3Y-EC and the 4Y-EC engines install the thrust washers on the number 3 bearing cap with the oil grooves facing outward.
- 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 side play, if correct assemble the rest of the engine.
BEARING OIL CLEARANCE
Remove cap from the bearing to be checked. Using a clean, dry rag, thoroughly clean all oil from crankshaft journal and 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 bearing insert, reinstall cap, and torque to specifications.
Specifications are given earlier in this section.
Remove bearing cap, and determine bearing clearance by comparing width of Plastigage® to the scale on Plastigage® envelope. Journal taper is determined by comparing width of the bearing insert, reinstall cap, and torque to specifications.
Do not rotate crankshaft with Plastigage® installed. If bearing insert and journal appear intact, and are within tolerances, no further main bearing service is required. If bearing or journal appear defective, cause of failure should be determined before replacement.
CRANKSHAFT END-PLAY/CONNECTING ROD
Place a prybar between a main bearing cap and crankshaft casting taking care not to damage any journals. Pry backward and forward, measure the distance between the thrust bearing and crankshaft with a feeler gauge. Compare reading with specifications. If too great a clearance is determined, a main bearing with a larger thrust surface or crank machining may be required. Check with an automotive machine shop for their advice.
Connecting rod clearance between the rod and crank throw casting can be checked with a feeler gauge. Pry the rod carefully on 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 engine must be removed from the car and disassembled, 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.