Chevrolet 10 Series 1970, Service Manual

Page: 483 / 671

CLUTCHES AND TRANSMISSIONS 7-53
O il le v e l should be checked with the s e le c to r le v e r in
the P a rk (P ) o r (N ) N eu tral fo r 30 S eries Trucks p o si­
tion, engine running, and the veh icle on le v e l pavement.
Fluid le v e l should be to the F U L L m ark with the tran s­
m ission at n orm al operating tem perature (180°F.). W ith
w arm flu id (room tem peratu re 80°F.), the le v e l should
be at o r 1/4 inch below the ADD m ark. (See checking
p roced u re)
If o il le v e l was low, r e fe r to O il Leaks.
The condition of the o il is often an indication of whether
the tran sm ission should be rem oved fro m the veh icle, o r
to make fu rth er tests. When checking o il le v e l, a burned
s m e ll and discoloration indicate burned clutches o r bands
and the tran sm ission w ill have to be rem oved.
M A N U A L LINKAGE
Manual linkage adjustment and the associated neutral
safety sw itch a re im portant fro m a safety standpoint.
The neutral sa fety sw itch should be adjusted so that the
engine w ill sta rt in the P a rk and N eu tral positions only.
W ith the s e le c to r le v e r in the P a rk position, the park­
ing pawl should fr e e ly engage and p reven t the veh icle
fr o m ro llin g . The poin ter on the indicator quadrant
should line up p ro p e rly with the range indicators in a ll
ranges.
OIL LEAKS
B e fo re attempting to c o r r e c t an o il leak, the actual
sou rce of the leak must be determ ined. In many cases
the source of the leak can be d eceivin g due to “ wind
flo w " around the engine and transm ission.
The suspected a re a should be wiped clean of a ll o il
b e fo re inspecting fo r the source of the leak. Red dye is
used in the tran sm ission o il at the assem bly plant and
w ill indicate if the o il leak is fro m the transm ission.
The use of a “ black light” * to iden tify the o il at the
sou rce of leak is also helpful. Com paring the o il fro m
the leak to that on the engine o r tran sm ission dip stick
(when view ed by "b la c k lig h t " ) w ill d eterm in e the source
of the leak.
O il leaks around the engine and tran sm ission are gen­
e r a lly c a rrie d tow ard the r e a r of the truck by the a ir
strea m . F o r exam ple, a tran sm ission “ o il filt e r tube to
case leak” w ill som etim es appear as a leak at the re a r
of the tran sm ission . In determ in in g the source of an o il
leak it is m ost helpful to keep the engine running.
POSSIBLE POINTS OF OIL LEAKS
1. T R A N S M IS S IO N O IL P A N L E A K
a. Attaching bolts not c o r r e c tly torqued.
b. Im p ro p e rly in stalled o r damaged pan gasket.
c. O il pan gasket mounting face not flat.
2. R E A R EX TE N SIO N L E A K
a. Attaching bolts not c o r r e c tly torqued.
b. R ea r s e a l assem bly - damaged o r im p ro p erly
installed.
c. Gasket sea l - (extension to case) damaged o r im ­
p ro p e rly installed.
d. Porou s casting.
3. CASE L E A K
a. F ille r pipe “ O” rin g sea l damaged o r m issing;
m isposition o f f i l l e r pipe b racket to engine -
“ loading” one side of “ O” ring.
b. M odulator assem bly “ O” rin g s e a l - damaged o r
im p ro p erly installed.
c. G overn or cover, gasket and bolts - damaged,
loose, case fa ce leak.
d. Speedo gea r - “ O” ring damaged.
e. Manual shaft sea l - damaged, im p ro p e rly installed.
f . Line p re s s u re tap plug - stripped, shy s e a le r
compound.
g. Park in g pawl shaft cup plug - damaged, im prop­
e r ly installed.
h. Vent pipe (r e fe r to Item 5).
i . P orou s case.
4. F R O N T END L E A K
a. Fron t sea l - damaged (check co n v e rte r pack fo r
nicks, etc., also fo r pump bushing m oved f o r ­
w ard); ga rte r sprin g m issin g fro m pump to con­
v e r t e r seal.
b. Pump attaching bolts and seals - damaged, m is s ­
ing, bolts loose.
c. C on verter - leak in weld.
d. Pump “ O” rin g s e a l - damaged. (A ls o check
pump g roove and case b o re).
e. P orou s casting (pump o r case).
5. O IL COMES OU T V E N T P IP E
a. T ran sm ission o v e r - fille d .
b. W a ter in oil.
c. Pump to case gasket m ispositioned.
d. F o reign m a te ria l between pump and case, o r be­
tween pump c o v e r and body.
e. Case - porous, pump face im p ro p erly machined.
f . Pump - shy of stock on mounting fa ces, porous
casting.
CASE POROSITY—REPAIR
T ra n sm ission leaks caused by aluminum case p o ro sity
have been su ccessfu lly re p a ire d with the tran sm ission in
the v e h icle by using the fo llo w in g procedure.
1. Road test and b rin g the tran sm ission to operating
tem perature.
2. R aise the ca r and, with the engine running, locate the
source of the o il leak. Check fo r leaks in a ll op erat­
ing positions.
NOTE: The use of a m ir r o r w ill be helpful in
finding leaks.
3. Shut o ff engine and thoroughly clean area with a
solvent and a ir dry.
4. Using the instruction of the m anufacturer, m ix a suf­
ficien t amount of epoxy cement, part #1360016, to
make the rep a ir.
5. W hile the tran sm ission is s t ill hot, apply the epoxy
to the area, making certain that the area is fu lly
covered.
6. A llo w epoxy cem ent to d ry fo r th ree hours and r e ­
test fo r leaks, as outlined in Steps 1 and 2.
OIL PRESSURE CHECK
W ith Vehicle Stationary
1. O il P re s s u re Check - Road o r N o rm a l Operating
Conditions
i
* A "b la c k light” testin g unit may be obtained fro m s e v e r a l d ifferen t tool supplies.
CHEVROLET TRUCK SERVICE MANUAL