Oil Cooler Lines; Checking And Adding Fluid - GMC G Service Manual

7A-64 TRANSMISSION

OIL COOLER LINES

If replacement of transmission steel tubing cooler lines is
required, use only double wrapped and brazed steel tubing
meeting GM specification 123M or equivalent. Under no
condition use copper or aluminum tubing to replace steel
tubing. Those materials do not have satisfactory fatigue
durability to withstand normal vehicle vibrations. Steel tub­
ing should be flared using the double flare method.
COOLER LINE FLUSHING
In a major transmission failure, where particles of metal
have been carried with the oil throughout the units of the
transmission, it will be necessary to flush out the oil cooler
and connecting lines. To flush the oil cooler and lines, use
the following procedure:
1. Disconnect both cooler lines from the transmission.
2. Place a hose over the end of the cooler inlet line (from
the bottom of the cooler) and insert the hose into an
empty container.
3. Flush clean oleum solvent or equivalent through the
return line (from the top of the cooler) using an oil
suction gun until clean solvent comes out of the hose.
This will "backflush" the cooler.
4. Remove the hose from the inlet cooler line and place
it on the return line.
5. Flush clean oleum solvent or equivalent through the
inlet line until clean solvent comes out the return line.
Remove remaining solvent from cooler with com­
pressed air applied to the return line and flush with
transmission fluid.
6. Reconnect oil cooler lines and torque nuts to 17 N«m
(12 ft. lbs.).

CHECKING AND ADDING FLUID

The automatic transmission is designed to operate at the
"FULL HOT" mark on the dipstick at normal operating tem­
peratures of 88°C-93°C (190°F-200°F), and should be
checked under these conditions (figure 69).
The normal operating temperature is obtained only after
at least 24 km (15 miles) of highway type driving.
If the vehicle has recently been operated for an
extended period at high speed or in city traffic in hot
weather or the vehicle is being used to pull a trailer, an
accurate fluid level cannot be determined until the fluid has
cooled down, usually about 30 minutes after the vehicle has
been parked.
Ii? | Inspect
1. Park vehicle on level ground.
2. Apply parking brake and block wheels.
3. Start engine and operate vehicle for 15 minutes or
until a normal operating temperature is reached.
4. Move gear selector through all gear positions.
5. Move gear selector to "Park" (P).
6. Check fluid level, color and condition. Refer to 'Trans-
mission Fluid Information" in this section.
I ? | Important
DO NOT OVERFILL.Overfilling can cause foaming and
loss of fluid through the vent. Slippage and transmission
failure can result.
Fluid level too low can cause slipping, particularly, when
the transmission is cold or the vehicle is on a hill.
SHIFT LINKAGE
H
Remove or Disconnect (Figure 70)
• Apply the parking brake.
1. Retaining pin (326).
2. Rod (340) from the column lever.
• Note the position of any washers, spacers and
insulators removed.
3. Rod (340) from the equalizer lever (338).
— R/V and P-Models.
• Screw (342) and the washer (341).
• Swivel (332).
— G-Van.
• Nut (336), washers and the insulator.
• Swivel (332).
• Spacer and the retainer.
4. Retaining pin (327) and the equalizer lever (338).
• Insulator, washer and the spring.
FiiiH Clean
• Metal parts using solvent. Wipe dry using a clean, dry
rag.
• Rubber or nylon parts using soapy water. Wipe dry
using a clean, dry rag.
H Install or Connect (Figure 70)
1. Equalizer lever (338) and a new retaining pin (327).
• Spring, washer and the insulator.
2. Rod (340) to the equalizer lever (338).
— R/V and P-Models.
• Swivel (332).
• Washer (341) and the screw (342).