Balance Shaft: Service and Repair
REMOVALBALANCE SHAFTS/CHAIN/SPROCKETS
NOTE: For service procedures requiring only temporary relocation of carrier assembly refer to BALANCE SHAFT CARRIER procedure below.
1. Drain engine oil.
2. Remove the oil pan and pick-up tube.
3. If replacing crankshaft sprocket, remove oil pump.
4. Remove chain cover, guide and tensioner. Discard pivot screw and adjuster screw. (Fig. 129).
5. Remove screw retaining balance shaft drive sprocket (Fig. 130). Remove chain and sprocket.
6. Using two wide pry bars, work the crankshaft sprocket back and forth until it is off the crankshaft-shaft.
7. Remove gear cover retaining stud (double ended to also retain chain guide). Remove cover and balance shaft gears (Fig. 131).
8. Remove rear cover and balance shafts (Fig. 132).
9. Remove four carrier to crankcase attaching bolts to separate carrier from engine bedplate.
BALANCE SHAFT CARRIER
The following components will remain intact during carrier removal: Gear cover, gears, balance shafts and the rear cover (Fig. 128).
1. Drain engine oil.
2. Remove the oil pan and pick-up tube.
3. Remove chain cover, guide and tensioner (Fig. 129).
4. Remove screw retaining balance shaft drive sprocket (Fig. 130).
5. Move balance shaft inboard through drive chain sprocket. Sprocket will hang in lower chain loop.
6. Remove carrier to crankcase attaching bolts to remove carrier.
INSTALLATION
BALANCE SHAFT INSTALLATION/TIMING
Balance shaft and carrier assembly installation is the reverse of the removal procedure. During installation crankshaft-to-balance shaft timing must be established. Refer to Timing procedure.
1. With balance shafts installed in carrier (Fig. 128) position carrier on crankcase and install four attaching bolts and tighten to 54 Nm (40 ft. lbs.).
2. Turn balance shafts until both shaft key ways are up, parallel to vertical centerline of engine. Install short hub drive gear on sprocket driven shaft and long hub gear on gear driven shaft. After installation gear and balance shaft keyways must be up with gear timing marks meshed as shown in (Fig. 133).
3. Install gear cover and tighten double ended stud/washer fastener to 12 Nm (105 inch lbs.).
4. Align flat on balance shaft drive sprocket to the flat on crankshaft (Fig. 134).
5. Install balance shaft drive sprocket on crankshaft using Special Tool 6052 (Fig. 135).
6. Turn crankshaft until number 1 cylinder is at top dead center (TDC). The timing marks on the chain sprocket should line up with the parting line on the left side of number one main bearing cap. (Fig. 136).
7. Place chain over crankshaft sprocket so that the plated link of the chain is over the number 1 cylinder timing mark on the balance shaft crankshaft sprocket (Fig. 136).
8. Place balance shaft sprocket into the timing chain (Fig. 136) and align the timing mark on the sprocket (dot) with the (lower) plated link on the chain.
NOTE: The lower plated link is 8 links from the upper link.
9. With balance shaft keyways pointing up (12 o'clock) slide the balance shaft sprocket onto the nose of the balance shaft. The balance shaft may have to be pushed in slightly to allow for clearance.
NOTE: THE TIMING MARK ON THE SPROCKET, THE (LOWER) NICKEL PLATED LINK, AND THE ARROW ON THE SIDE OF THE GEAR COVER SHOULD LINE UP WHEN THE BALANCE SHAFTS ARE TIMED CORRECTLY.
10. If the sprockets are timed correctly, install the balance shaft bolts and tighten to 28 Nm (250 inch lbs.). A wood block placed between crankcase and crankshaft counterbalance will prevent crankshaft and gear rotation.
11. CHAIN TENSIONING:
a. Install chain tensioner loosely assembled with new shouldered pivot screw and adjuster screw.
b. Position guide on double ended stud making sure tab on the guide fits into slot on the gear cover. Install and tighten nut/washer assembly to 12 Nm (105 inch lbs.).
c. Place a shim 1 mm (0.039 inch) thick x 70 mm (2.75 inch) long between tensioner and chain. Push tensioner and shim up against the chain. Apply firm pressure 2.5 - 3 Kg (5.5 - 6.6 lbs.) directly behind the adjustment slot to take up all slack. Chain must have shoe radius contact as shown in (Fig. 137).
d. With the load applied, tighten top tensioner bolt first, then bottom pivot bolt. Tighten bolts to 12 Nm (105 inch lbs.). Remove shim.
e. Install carrier covers and tighten screws to 12 Nm (105 inch lbs.).
12. If removed, install oil pump.
13. Install pick-up tube and oil pan.
14. Fill engine crankcase with proper oil to correct level.