Jeep Wrangler TJ. Manual — part 437
BALANCE SHAFTS AND
CARRIER ASSEMBLY
DESCRIPTION
The 2.4L engine is equipped with two nodular cast
iron balance shafts installed in a cast aluminum car-
rier attached to the lower cylinder block (Fig. 108).
OPERATION
The balance shafts are driven by the crankshaft
via a roller chain and sprockets. The balance shafts
are connected by helical gears. The dual counter
rotating shafts decrease second order vertical shak-
ing forces caused by component movement.
REMOVAL
BALANCE SHAFTS/CHAIN/SPROCKETS
NOTE: For service procedures requiring only tem-
porary relocation of carrier assembly refer to BAL-
ANCE SHAFT CARRIER procedure below.
(1) Drain engine oil.
(2) Remove the oil pan and pick-up tube (Refer to
9 - ENGINE/LUBRICATION/OIL PAN - REMOVAL).
(3) If replacing crankshaft sprocket, remove oil
pump (Refer to 9 - ENGINE/LUBRICATION/OIL
PUMP - REMOVAL).
(4) Remove chain cover, guide and tensioner. Dis-
card pivot screw and adjuster screw. (Fig. 109).
(5) Remove screw retaining balance shaft drive
sprocket (Fig. 110). 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. 111).
(8) Remove rear cover and balance shafts (Fig.
112).
(9) Remove four carrier to crankcase attaching
bolts to separate carrier from engine bedplate.
BALANCE SHAFT CARRIER
The following components will remain intact dur-
ing carrier removal: Gear cover, gears, balance shafts
and the rear cover (Fig. 108).
(1) Drain engine oil.
(2) Remove the oil pan and pick-up tube (Refer to
9 - ENGINE/LUBRICATION/OIL PAN - INSTALLA-
TION).
(3) Remove chain cover, guide and tensioner (Fig.
109).
Fig. 108 Balance Shafts and Carrier Assembly
1 - SPROCKET
7 - GEARS
2 - TENSIONER
8 - GEAR COVER
3 - PLUG
9 - CHAIN COVER
4 - CARRIER
10 - SPROCKET
5 - REAR COVER
11 - GUIDE
6 - BALANCE SHAFTS
12 - CHAIN
TJ
ENGINE 2.4L
9 - 63
(4) Remove screw retaining balance shaft drive
sprocket (Fig. 110).
(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.
Fig. 109 Chain Cover, Guide and Tensioner
1 - STUD
2 - TENSIONER (ADJUSTER)
3 - GEAR COVER
4 - ADJUSTER SCREW
5 - SHOULDERED PIVOT SCREW
6 - CHAIN COVER (CUTAWAY)
7 - GUIDE
Fig. 110 Drive Chain and Sprockets
1 - NICKEL PLATED LINK AND MARK
2 - GEAR/SPROCKET SCREWS
3 - NICKEL PLATED LINK AND DOT
Fig. 111 Gear Cover and Gears
1 - STUD (DOUBLE ENDED)
2 - DRIVE GEAR
3 - DRIVEN GEAR
4 - CARRIER DOWEL
5 - GEAR(S)
6 - GEAR COVER
Fig. 112 Balance Shaft(s)—Removal/Installation
1 - REAR COVER
2 - CARRIER
3 - BALANCE SHAFT
9 - 64
ENGINE 2.4L
TJ
BALANCE SHAFTS AND CARRIER ASSEMBLY (Continued)
INSTALLATION
BALANCE SHAFT INSTALLATION/TIMING
Balance shaft and carrier assembly installation is
the reverse of the removal procedure. During instal-
lation crankshaft-to-balance shaft timing must
be established. Refer to Timing procedure in
this section.
(1) With balance shafts installed in carrier (Fig.
108) position carrier on crankcase and install four
attaching bolts and tighten to 54 N·m (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 instal-
lation gear and balance shaft keyways must be up
with gear timing marks meshed as shown in (Fig.
113).
(3) Install gear cover and tighten double ended
stud/washer fastener to 12 N·m (105 in. lbs.).
(4) Align flat on balance shaft drive sprocket to the
flat on crankshaft (Fig. 114).
(5) Install balance shaft drive sprocket on crank-
shaft using Special Tool 6052 (Fig. 115).
Fig. 113 Gear Timing
1 - KEY WAYS UP
2 - GEAR ALIGNMENT DOTS
Fig. 114 Balance Shaft Sprocket Alignment to
Crankshaft
1 - ALIGN FLATS
Fig. 115 Balance Shaft Drive Sprocket - Installation
1 - SPROCKET
2 - SPECIAL TOOL 6052
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ENGINE 2.4L
9 - 65
BALANCE SHAFTS AND CARRIER ASSEMBLY (Continued)
(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. 116).
(7) Place chain over crankshaft sprocket so that
the plated link of the chain is over the number 1 cyl-
inder timing mark on the balance shaft crankshaft
sprocket (Fig. 116).
(8) Place balance shaft sprocket into the timing chain
(Fig. 116) 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 N·m (250 in.
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 adjuster screw and shouldered pivot
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 N·m (105 in. lbs.).
(c) Place a shim 1 mm (0.039 in.) thick x 70 mm
(2.75 in.) 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. 117).
(d) With the load applied, tighten top tensioner
adjuster bolt first, then bottom shouldered pivot
bolt. Tighten bolts to 12 N·m (105 in. lbs.). Remove
shim.
(e) Install carrier covers and tighten screws to
12 N·m (105 in. lbs.).
(12) If removed, install oil pump (Refer to 9 -
ENGINE/LUBRICATION/OIL PUMP - INSTALLA-
TION).
Fig. 117 Chain Tension Adjustment
1 - 1MM (0.039 IN.) SHIM
2 - TENSIONER (ADJUSTER) BOLT
3 - SHOULDERED PIVOT BOLT
Fig. 116 Balance Shaft Timing
1 - MARK ON SPROCKET
2 - KEYWAYS UP
3 - ALIGN MARKS
4 - PLATED LINK
5 - PARTING LINE (BEDPLATE TO BLOCK)
6 - PLATED LINK
9 - 66
ENGINE 2.4L
TJ
BALANCE SHAFTS AND CARRIER ASSEMBLY (Continued)
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