How to Replace the Rod Bearings on a Toyota Camryby Don Bowman
Bad rod bearings on any engine will quickly tear up the journals on the crankshaft, making replacement of the bearings useless. If the rod bearings knock for a brief second when the engine is started cold, not to be heard again during normal operation, replacement is usually effective. The rod caps need to be removed and the crank inspected for wear for feasibility of replacement.
Raise and support the front of the vehicle securely on jack stands. Drain the engine oil in the drip pan and dispose of it properly. Remove the oil pan bolts using the 3/8-inch drive socket, extension and ratchet. Remove the oil pan. It may be necessary to pry it along the sides with the common screwdriver.
Turn the crankshaft clockwise to bring the closest journal to the front of the motor to bottom center. This means the journal and connecting rod are at their lowest level for accessibility. Turn the crank with a socket and ratchet on the crankshaft bolt in the center of the crankshaft pulley.
Check the connecting rod and cap for looseness and free play on the crankshaft journal. Grab the connecting rod and try to move it up and down. There should be no movement at all.
Remove the connecting rod cap using a socket and ratchet. Be careful when removing the connecting rod caps inasmuch as they need to go back on the same way that they came off. They will not fit if they are turned around, as they will rub the opposing rod cap and cause damage. All the rod caps are usually numbered to match a particular rod. There is a number stamped on the side by the rod bolt. There is also a corresponding number on the side of the rod cap. When the cap is installed, the numbers on the rod and the cap should be one over the other.
Inspect the rod bearing for a copper color and thickness indicating wear. Look for uneven wear on the bearing in the cap. This is a way of locating a problem cylinder.
Inspect the surface of the crankshaft journal for severe scratches or grooving. If any of these are present to the degree that they can be felt with a fingernail, work stops here. The crank is trashed and new bearings will only work for a matter of minutes to a few hours. The grooves will tear up the new bearings quickly. If all looks well, there are no grooves in the crank journal and the bearings are evenly worn, the next step is to check the clearances.
Remove the bearing from the connecting rod cap and turn it over. Look at the bottom side for STD stamped into the bearing or a number, such as .010. The STD means that the crank is original size and has not been turned. If you see a number, this means that the journal has been cut. If the number is .010, a bearing that is .010 oversized is needed. Purchase a set of bearings to match what was found on the underside of the bearing.
Tap the connecting rod up slightly using the wooden handle on the hammer. Place the handle on one of the connecting rod studs and with the other hand slap the head of the hammer with the palm of the hand just enough for the rod to rise above the crank journal. Very gently, so as not to scratch the crank journal, use a common screwdriver to push the upper bearing out of the connecting rod. Inspect the bearing as before.
Check the clearance in the rod to journal using the plastigauge. The plastigauge is a hair thickness piece of plastic in a flat paper container. Clean the oil off the bearing with the carburetor cleaner. Spray the bearing, cap and the bottom of the journal. Oil will destroy the plastigauge. The plastigauge gets placed perpendicularly on the connecting rod cap bearing. The cap is then installed and tightened. Once tightened, it is then removed and the plastigauge inspected. The tighter the bearing is, the more it compresses the plastigauge. When the plastigauge is compressed, it flattens out. The wider that it is, the tighter the fit of the cap to the journal.
Hold the cap up with the plastigauge and compare the width to the package it came in. On the paper, there are colored squares of different widths and a number under each. Compare the plastigauge to these and choose the one closest and read the number. As long as the plastigauge shows less than .003 the crank can be saved. It is allowed to be between .001 to .003 thousandths clearance.
Install the upper bearing so the raised edge is on the same side as the edge on the cap. Install the cap with bearing and put the nuts on and tighten snugly. Check all the remaining journals. It is not necessary to plastigauge all of them since the first shows good. Do not remove the upper bearings either. Just move the journal down by turning the crank and inspect the cap bearing and the journal. As long as they all look good, the new bearing can be put in.
Install the new bearings. Start at the first one again. Bring the journal down by turning the crank. Remove the connecting rod cap. Use the hammer's handle and tap the connecting rod up ever so slighty. Remove the upper bearing. Remember, the proper orientation of the bearings is pertinent.
Smear some STP on the bearings prior to installing them. Install the bearing followed by the cap and tighten to 18 foot pounds of torque and then an additional 90 degrees. Do the rest of the connecting rods in the same manner.
Install all remaining parts in reverse order of removal.