TRUCK SERVICE MANUAL
Section 3. PREVENTIVE MAINTENANCE
input pump and is directed to the clutches and converter,
3-1. SCOPE OF SECTION 3
causing converter cavitational noises and irregular
shifting. The aeration also changes the viscosity and
This section covers routine and periodical
color to a thin milky liquid.
procedures required to maintain the transmission in good
Included are instructions for
(3) The normal oil level (full mark ,n dipstick)
inspection, care of the oil system and breather, linkage
is 1 1/2 inches (38.9 mm) below the oil pan split line.
adjustment, care of external lines, oil filter and oil cooler,
The full mark should not be exceeded.
stall testing, storage, and checking oil pressures.
Troubleshooting information is tabulated at the end of
(4) A defective seal-ring 24 (A, foldout 14) on
the filter intake pipe will cause the input pump to draw air
into the oil system. Air thus entering the oil will result in
3-2. INSPECTION AND CARE
the conditions described in (2), above.
The transmission should be kept clean to make
c. Protect Fill Pipe. When adding oil or checking oil
inspection easier. Check for loose bolts, loose or leaking
level, dirt or foreign material must not be allowed to enter
oil lines, oil leakage, and condition of control linkage and
the fill pipe. Before removing the dipstick, clean around
cables. Check the transmission oil level at the intervals
the end of the fill pipe.
specified in the vehicle operator's manual.
d. Oil Level Check Procedure.
3-3. CHECKING OIL LEVEL
speed and oil temperature significantly affect the oil level.
Thus, the speed and temperature must be controlled for
a. Importance of Proper Level. Maintaining the
an accurate c h e c k. The oil I e v e l should be checked
proper oil level is very important. If, during check
by the following procedure.
procedure (d. below), inconsistent dipstick readings
occur, look for proper venting of the transmission
(1) Operate the transmission until normal
breather (para 3-9). The transmission oil is used to
operating temperature (160 to 200°F) is reached.
apply clutches and lubricate and cool the components. If
the oil level is too low the result can be poor performance
(2) Shift the transmission through all drive
(clutches will not receive adequate oil supply). If the oil
ranges to fill the clutch cavities and oil passages.
level is too high, overheating results from the oil being
churned and aerated. Drain any excess oil to restore the
(3) With the vehicle positioned on level
proper level; refer to e, below.
ground, allow the engine to idle. Shift to neutral and
apply the parking brake.
b. Foaming and Aerating
(1) Transmission performance will be affected
when the oil foams or aerates. The primary causes of
aeration are, low oil in the sump, too much oil in the
sump, or a defective or missing seal-ring on the intake
(2) A low oil level (denoted on the dipstick) will
not completely envelope the oil filter. Therefore oil and
air is drawn by the