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TRANSFER CASE
21-131
(engine, transmission, etc.) can be b l o w n back onto
the transfer case b y a i r flow under t h e vehicle. A
blocked transfer case v e n t can also cause leakage a t
the shaft seals due t o i n t e r n a l pressure b u i l d up.
O v e r f i l l i n g the transfer case can force fluid out the
vent and be m i s t a k e n for a leak. Correct fluid level
checking methods should prevent o v e r f i l l problems.
Checking Fluid Level
The correct method o f checking transfer case
fluid
level requires t h a t the vehicle be level. I f fluid level
is checked w i t h the vehicle parked o n t h e shop floor,
be sure the floor area used is level. I f a hoist is used,
a drive-on, or swivel a r m type i s preferred.
A l l o w t h e transfer case fluid t o settle for a m i n u t e
or so before checking. Correct fluid level is t o t h e
bottom edge o f the fill p l u g hole.
HARD
SHIFTING
H a r d s h i f t i n g is generally caused b y misadjusted
linkage, loose linkage or d r i v e l i n e components, drive-
l i n e torque loads caused b y operation o n h a r d paved
surfaces i n 4 W D , improper s h i f t i n g techniques, or a
lack o f l u b r i c a n t w h i c h caused i n t e r n a l wear a n d
damage.
Loose l i n k a g e or d r i v e l i n e components are a result
of improperly tightened, stripped, or m i s s i n g fasten-
ers. Remember t h a t loose crossmember a n d m o u n t i n g
parts can also generate a h a r d shift condition.
Torque loads i n t h e transfer case can cause h a r d
s h i f t i n g or even prevent s h i f t i n g . Such loads are gen-
erally a product o f extensive
operation o n h a r d ,
paved surfaces i n 4 W D range, u n e q u a l size tires, or
by mismatched front/rear axle gear ratios.
L i n k a g e adjustment should be performed as de-
scribed i n the service section. Improper shift and op-
e r a t i n g techniques can be corrected b y i n s t r u c t i n g
the driver. I n t e r n a l component damage w i l l require
overhaul t o correct.
NOISE
Some transfer case operating noise i s n o r m a l . The
r o t a t i n g gear t r a i n can produce sounds t h a t may be-
come audible a t higher speeds a n d loads. However,
unusual noise is a n indicator t h a t i n t e r n a l compo-
nents may be w o r n or damaged.
Low l u b r i c a n t levels are a frequent cause o f noisy
operation. Insufficient l u b r i c a n t w i l l lead t o over-
heating, subsequent damage t o b e a r i n g a n d gear sur-
faces and h a r d shifting.
Transfer case bearing noise is h i g h e r i n p i t c h t h a n
gear noise. I f the u n i t is noisy i n 4 W D range only,
the front shaft bearings are probably a t fault. I f the
u n i t is noisy i n a l l ranges, a n overhaul w i l l be nec-
essary t o locate the f a u l t y bearing.
Gear noise is lower i n p i t c h and u s u a l l y most no-
ticeable w h e n engaged and under load. Gear noise i n
4 W D drive range only is a n indicator t h a t the front
shaft gears are damaged. Noise i n a l l ranges could be
the idler or drive gears. A n o v e r h a u l w i l l be neces-
sary t o determine w h i c h is a t f a u l t .
Frequently, suspected transfer case noise may actu-
a l l y originate from another d r i v e l i n e component. The
p r o x i m i t y o f other d r i v e l i n e components can some-
times make i t difficult t o p i n p o i n t t h e noise source.
TRANSFER
CASE OPERATIONAL
CHECK
The transfer case should n o t be removed u n t i l d i -
agnosis
indicates t h e u n i t has actually malfunc-
tioned. I f a transfer case problem i s suspected, check
and verify
operation before a t t e m p t i n g repair. A
transfer case operational check m a y reveal t h a t a
problem is actually r e l a t e d t o another driveline com-
ponent.
(1) Raise the vehicle o n a hoist t h a t w i l l allow a l l
four wheels to rotate.
(2) Check l u b r i c a n t level. I f l u b r i c a n t level is low,
check for leaks a t t h e b e a r i n g a n d seal retainers,
yokes, drain/fill plugs, P T O cover and vent.
(3) I f the vehicle i s equipped w i t h l o c k i n g hubs, en-
gage the hubs.
(4) S t a r t t h e engine, shift t h e transmission i n t o
gear and operate t h e transfer case i n a l l ranges. Ob-
serve propeller shaft action, shift efforts and opera-
t i o n a l sound levels as follows:
(a) Only the r e a r propeller shaft should rotate
i n two-wheel drive. B o t h propeller shafts should
both rotate i n four-wheel
drive h i g h a n d l o w
ranges.
(b) I f the front propeller shaft d i d not rotate i n
either four-wheel d r i v e range, t h e transfer case
shift components m a y be w o r n or damaged. O r , i f
the front shaft d i d rotate b u t t h e f r o n t wheels d i d
not, check the f r o n t axle shift mechanism and t h e
locking hubs ( i f equipped).
(c) I f both propeller shafts rotate i n four-wheel
drive b u t the wheels on one axle d i d not rotate, the
problem is i n the axle.
(d) I f neither propeller shaft rotates i n any
range, the problem is i n the transmission or t r a n s -
fer case. To determine w h i c h component is a t fault,
proceed t o next step.
(5) Determine i f f a u l t is w i t h transfer case or
transmission as follows:
(a) Raise vehicle and disconnect b o t h propeller
shafts a t the transfer case.
(b) Position supports under t h e transmission.
(c) Remove the bolts/nuts a t t a c h i n g the transfer
case adapter to t h e crossmember and transmission.
(d) Support t h e transfer case w i t h a transmis-
sion j a c k and slide t h e transfer case and adapter
clear o f the transmission o u t p u t shaft.
(e) Have helper s t a r t engine and shift transmis-
sion i n t o gear. I f transmission o u t p u t shaft rotates,
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