Chevrolet CHEVY VAN G10 SERIES Service Manual page 251

6
. Allow epoxy cem ent to dry for three hours and retest for
leaks, as outlined in Steps l and 2.
O IL PRESSURE CHECK
W ith Car Stationary
Transmission oil pressure gauge and engine tachom eter
should be connected and the oil pressures should check as
follows:
1. Pressures (PS1) indicated below are at 0 o u tp u t speed
w ith the vacuum m odulator tube disconnected and with
1 200
engine at rpm .
2. Pressures (PSI) indicated below are at 0 o utpu t speed
w ith the vacuum m odulator tube connected, and w ith
sufficient engine speed to m aintain 16 inches Hg absolute
m anifold pressure.
A pproxim ate A ltitude
o f Check (F t. Above
V ACUUM MODULATOR ASSEMBLY
1. Vacuum Diaphragm Leak Check
Insert a pipe cleaner into the vacuum connector pipe as far
as possible and check for the presence o f transm ission oil. If
oil is found, replace the m odulator.
N O T E : Gasoline or water vapor may settle in the
vacuum side of the m odulator. If this is found
w ith o u t the presence of oil, the m odulator should
not be changed.
A bsolute
M anifold
Sea Level) Pressure
( " Hg)
0 16
2 00 0 16
4 0 0 0
16
6 0 0 0
16
8 0 0 0 16
10000 16
12000 16
14000 16
CLUTCHES & TRANSMISSIONS 7-15
Approxim ate Drive
A ltitude o f Check Neutral
(F t. A bove Park
Sea Level)
0
2000
4 0 0 0
6 0 0 0
80 0 0
10000
12000
1 4 000'
Drive -6
L and
-8
N eutral
V
Park
L I or L2
76 94
79
96
82 98
85 100
87 102
90 103
92
105
94
107
2. Atmospheric Leak Check
Apply a liberal coating o f soap bubble solution to the
vacuum connector pipe seam, the crimped upper to lower
housing seam (Fig. 4). Using a short piece o f rubber tubing,
apply air pressure to the vacuum pipe by blowing into the tube
and observe for leak bubbles. If bubbles appear, replace the
m odulator.
N O T E : Do not use any method other than human
lung power for applying air pressure, as pressures
over 6 psi may damage the modulator.
ENDS TO BE SQUARE
SCRIBED LINE
Fig. 5 —Bellows Comparison Gauge
L-6 and
V-8 Reverse
LI or L2
139 139
250
139 139
235
139 139 221
132 134
203
125 129 195
184
117 123
118
110 173
104 113
163
Reverse
120
124
129
133
137
141
144
148
1 3 /3 2 " TO 3 / 8 "
ROUND OR FLAT STOCK
C H E V Y V A N SH O P M A N U A L