REMOVAL & INSTALLATION
See Figures 1, 2 and 3
The 2.4L engine is equipped with 2 balance shafts installed in a carrier mounted to the lower crankcase. These balance shafts interconnect through gears to rotate in opposite directions. The gears are powered by a short, crankshaft-driven chain and rotate at 2 times the speed of the crankshaft. This will counterbalance certain reciprocating masses of the engine.
An oil passage from the No. 1 main bearing cap through the balance shaft carrier support leg provides lubrication to the balance shafts. This passage directly supplies engine oil to the front bearings and internal machined passages in the shafts that routes engine oil from the front to the rear shaft bearing journals.
Please note that this procedure requires removal of the timing belt. Valve train timing is critical to engine performance and to prevent engine damage. Work carefully and verify all timing marks as the engine is reassembled.
- Disconnect the negative battery cable.
- Remove the accessory drive belts. Refer to General Information & Maintenance .
- Remove the timing belt covers and timing belt, as outlined earlier in this section.
- Raise and safely support the vehicle.
- Place a large drain pan under the oil pan drain plug and drain the engine oil.
- Remove the oil pump and oil pan.
- Remove the balance shaft drive chain cover.
- Remove the drive chain guide and drive chain tensioner.
- Remove the gear cover retaining stud (double ended to also mount the drive chain guide).
- Remove the balance shaft gear and chain sprocket retaining screws.
- Remove the drive chain and chain sprocket assembly by using 2 prybars to work the sprocket back and forth until it is removed from the crankshaft.
- Remove the gear cover and balance shafts.
- Remove the 4 balance shaft carrier-to-crankcase mounting bolts, then separate the carrier from the engine bedplate.
- Install the balance shafts into the carrier and place the carrier into proper position against the engine bedplate. Install and tighten the 4 mounting bolts to 40 ft. lbs. (54 Nm).
- Rotate the balance shafts until both balance shaft keyways are pointed up parallel to the vertical centerline of the engine.
- Reinstall the short hub drive gear onto the sprocket driven balance shaft and the long hub gear onto the chain driven shaft. Once the gears are installed onto the shafts, the gear and balance shaft keyways must be up, and gear alignment dots properly meshed.
- Reinstall the gear cover and retaining stud fastener. Tighten the double ended retaining stud fastener to 105 inch lbs. (12 Nm).
- Reinstall the drive chain's crankshaft sprocket. Be sure to align the flat on the sprocket to the flat on the crankshaft, with the sprocket facing front.
- Rotate the crankshaft until the No. 1 cylinder is at Top Dead Center (TDC). The timing marks on the chain sprocket should align with the parting line on the left side of No. 1 main bearing cap.
- Place the drive chain around the crankshaft sprocket so the nickel plated link of the chain is on the No. 1 cylinder timing mark of the crankshaft sprocket.
- Reinstall the balance shaft sprocket into the drive chain. Be sure the timing mark on the balance shaft sprocket (yellow dot) lines up with lower nickel plated link on the chain.
- With the keyways of the balance shaft pointing up in the 12 o'clock position, slide the balance shaft drive chain sprocket onto the end of the balance shaft. If necessary to allow for clearance, the balance shaft may be pushed in slightly.
The lower nickel plated link, timing mark on the balance shaft sprocket, and arrow on the side of the gear cover should all line up when the balance shafts are properly timed.
- If the sprockets are timed correctly, install the balance shaft bolts and tighten to 250 inch lbs. (28 Nm). It may be necessary to place a wooden block between the crankcase and crankshaft counterbalance to prevent crankshaft and gear rotation.
- Install the drive chain tensioner, but keep it loose at this point.
- Position the drive chain guide onto the double ended stud fastener. Be sure the tab on the guide fits into the slot on the gear cover. Install the nut/washer assembly and tighten to 105 inch lbs. (12 Nm).
- Place a shim 0.039 in. x 2.75 in. (1mm x 70mm) long between the tensioner and chain. Push the tensioner and shim up against the chain. Apply pressure of 5.5-6.6 lbs. directly behind the adjustment slot to take up the slack. Be sure the chain makes shoe radius contact.
- With the pressure applied, tighten the top tensioner adjustment bolt first, then the lower pivot bolt. Tighten the bolts to 105 inch lbs. (12 Nm). Remove the shim after tightening the bolts.
- Install the chain cover and tighten the screws to 105 inch lbs. (12 Nm).
- Install oil pump and oil pan.
- Install the oil pan drain plug and gasket. Tighten the drain plug to 25 ft. lbs. (34 Nm).
- Lower the vehicle.
- Install the timing belt and timing belt covers, as described earlier in this section. It is very important that all valve timing marks align properly, or engine damage will result.
- Install the accessory drive belts, and adjust as necessary.
- Refill the engine with new, clean engine oil to the proper level. An oil filter change is also recommended.
- Reconnect the negative battery cable. Start the engine and check for leaks.