Crankshaft and Main Bearings

REMOVAL & INSTALLATION

1. Remove the engine from the car, as described earlier in this section.
2. Remove the front crankshaft pulley and the flywheel. (The flywheel removal procedure is found later in this section.)
3. Invert the engine on a suitable workstand, then remove the oil pan and rear main oil seal. If so equipped, also remove the rear cover.
4. Remove the front cover, timing chain/belt, and oil pump.
5. Mark all main and connecting rod bearing caps for location.

   Fig. 1: Unfasten the main bearing cap bolts . . .

   Fig. 2: . . . then remove each cap and bearing

   Fig. 3: Measure the length of each main bearing bolt before installation, and replace any that are out-of-range — 3.0L engine

   NOTE: You might want to check crankshaft end-play and main bearing oil clearances (as described under the installation procedure) at this time, before removing the bearing caps and crankshaft. In any event, be sure to check them when the crankshaft is reinstalled or replaced.

6. Unfasten the cap bolts, then remove the caps and bearings. (On engines in which the rear bearing cap also retains oil seals, you'll have to use a puller.) Keep all bearings and caps in position (and in order).
7. If the engine uses a manual transmission and has reached the normal time for overhaul, remove the pilot bearing (which supports the transmission input shaft) from the rear of the crankshaft with an appropriate puller.
8. Carefully lift the crankshaft from the cylinder block.
9. Clean and inspect the crankshaft for wear and run-out, and the bearings for wear, as described below. Repair or replace parts as necessary.

   To install:

10. Make sure all parts are clean and dry. Position the bearings in the engine block and bearing caps, then carefully lower the crankshaft into position. Install Plastigage® inserts on the main journals and crankpins, away from the oil holes. Assemble and torque the bearing and connecting rod caps (dry and in numbered order) with the arrows pointing forward. Be careful not to rotate the shaft. On the 3.0L engine, the main bearing cap bolts should be torqued in proper sequence to 14 ft. lbs. (20 Nm), then an additional 90 degrees and another 45 degrees after that. Also on the 3.0L engine, the connecting rod cap nuts should be torqued in proper sequence to 22 ft. lbs. (29 Nm), and then an additional 90 degrees. Paint reference marks on each bolt to assist with the angular torque. Remove the caps and check the bearing clearances by reading the width of the mark left by the insert in each case. Even if the crankshaft and bearings have passed their previous inspections, the crankshaft must be ground and undersize bearings installed, if clearances are improper.
11. Once the measured bearing clearances are correct, clean the insert marks off, thoroughly lubricate all wear surfaces with engine oil (bearing insert backs must remain dry), then reassemble and retorque all caps and cap bolts. On all GLC and 1979–82 2.0L engines, insert new side seals in the rear main cap grooves with their holes facing forward and backward, not side-to-side. On the 3.0L engine, measure the length of each main bearing bolt prior to final installation. The bolts are acceptable only if they are 3.35–3.37 in. (85.0–85.5mm). If any bolt length differs from this specification, replace that bolt.
12. Mount a dial indicator on the block with the pin resting against the end of the crankshaft. Push the shaft as far as it will go away from the indicator, then zero the indicator. Now, pull the crankshaft all the way toward the indicator and read the end-play. If excessive, adjust it with oversize thrust bearings (washers) or, in the case of 2.2L and 1983–87 2.0L engines, a standard undersize center bearing, including appropriate grinding of the center journal. The end-play check should be done in conjunction with a check of connecting rod side clearance, as previously described. Thrust bearings must be installed with the groove outward (toward the crankshaft thrust surface).

    Fig. 4: Main bearing cap bolt torque sequence — 3.0L engine

    Fig. 5: Use a torque wrench to properly torque the cap bolts

    Fig. 6: Insert new side seals in the rear main cap grooves with their holes facing forward and backward — GLC and 1979–82 626 engines

    Fig. 7: Mount a dial gauge against the end of the crankshaft to measure end-play

    Fig. 8: Carefully pry the shaft back and forth while reading the dial gauge

13. If applicable, tap the pilot bearing into the rear of the crankshaft using a piece of pipe the diameter of the outer bearing race. Be careful to apply pressure to the outer race only.
14. Install the rear main seal/cover, oil pump and oil pan, as described earlier in this section.
15. Install the timing chain/belt, front cover, etc. by referring to the appropriate procedures earlier in this section.