Hummer H1 Service Manual page 215

5-16 Transmission/Transfer Case
Fluid Level and Condition
Transmission fluid level and condition are important to proper
operation. An incorrect fluid level can lead to shift problems,
fluid breakdown, and accelerated wear.
Check fluid level and condition during the preliminary inspec-
tion procedure. This is important, as a low fluid level, or over-
fill condition can lead to slip and flare, overheating, burned
fluid, slow engagement, converter shudder, and no fourth gear
upshift.
An overfill condition allows the gear train to churn the fluid
into foam. this action aerates the fluid causing slip, overheat-
ing, oxidation, and overflow from the vent. A low level allows
the pump to take in air along with the fluid. Air in the fluid will
cause pressures to be low and develop slower than normal
shifts.
Checking Fluid Level
1. Fluid must be at normal operating temperature. Drive
vehicle 10-15 miles (15-24 km) if necessary.
2. Position vehicle on level surface.
3. Operate engine at idle speed.
4. Shift transmission into Park.
5. Clean dipstick and top of fill tube with shop towel to avoid
dirt entry.
6. Unlock and remove dipstick (Figure 5-19). Correct fluid
level is to hot full mark at top of crosshatch (Figure 5-18).
Adequate fluid level is anywhere in crosshatch area.
7. Note color and condition of fluid. Refer to fluid condition
check.
8. Add fluid only if level is below bottom mark of crosshatch
area. Add fluid in 1/4 to 1/2 pint/liter amounts to avoid
overfill. However, if overfill condition exists, drain
necessary amount of fluid with suction gun and length of
small plastic tubing. Or drain excess off at cooler line with
engine idling.
9. Install and lock dipstick and shut engine off.
ADD FLUID WHEN
LEVEL IS BELOW
THIS MARK
Figure 5-18: Transmission Fluid Level Marks
OK
CROSSHATCH
AREA
HOT
FULL MARK
_____________________________________________
Figure 5-19: Releasing Transmission Dipstick Lock
LIFT HANDLE
TO UNLOCK
TRANSMISSION
FILL TUBE DIPSTICK AND
LOCK HANDLE
Handle
®
FRONT
OF
VEHICLE