Hummer H1 Service Manual page 330

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Transmission Cooler Flushing Procedure
Equipment Needed
• J–35944-A cooler flushing tool with included adapters
and J–35944-22 or J–35944-CSE* flushing solution.
• Measuring Cup
• Funnel
• Water Supply (hot water recommended)
• Water Hose (at least 5/8" I.D.)
• Shop Air Supply (with water/oil filters, regulator and
pressure gauge)
• Air Chuck (with clip if available)
• Oil Drain Container
• Five Gallon Pail With Lid
• Eye Protection
• Rubber Gloves
* Do not substitute with solutions that contain alcohol or gly-
col. Use of solutions that contain alcohol or glycol may dam-
age J–35944-A, oil cooler or transmission components.
Preparation
1. After the repaired or replacement transmission is installed
in the vehicle, do not reconnect the oil cooler pipes.
2. Remove the fill cap on J–35944-A and fill with 20-21 oz.
(0.6L) of flushing solution. Do not overfill.
3. Install the fill cap on J–35944-A and pressurize the flusher
can using the shop air supply 80-100 psi (550-700 kPa).
4. Connect the J–35944-A discharge hose to the oil cooler
return pipe.
5. Clip the discharge hose onto the oil drain container.
6. Attach J–35944-A to the undercarriage of the vehicle with
the hook provided and connect the hose from J–35944-A
to the other (feed) oil cooler pipe.
7. With the water valve on J–35944-A in the "OFF" position,
connect the water hose from the water supply to J–35944-
A.
8. Turn "ON" the water supply at the water faucet.
Initial Flush
1. Turn the water valve on J–35944-A to the "ON" position
and allow the water to flow through the oil cooler and
pipes for 10 seconds to remove any remaining transmis-
sion fluid. If water does not flow through the oil cooler and
pipes, the cause of the blockage must be diagnosed and the
plugged component must be repaired or replaced. Con-
tinue with the cooler flushing and flow check procedure
once the blockage is corrected.
2. Turn the water valve on J–35944-A to the "OFF" position
and clip the discharge hose onto the five gallon pail with a
lid.
3. Turn the water valve on J–35944-A to the "ON" position
and depress the trigger to mix cooler flushing solution into
the water flow. Use the clip provided on the handle to hold
05745159
Transmission/Transfer Case
the trigger down. The discharge will foam vigorously
when the solution is introduced into the water stream.
4. Flush the oil cooler and pipes with water and solution for
two minutes. During this flush, attach the air supply to the
air valve located on J–35944-A for 3-5 seconds at the end
of every 15-20 second interval to create a surging action.
5. Release the trigger and turn the water valve on J–35944-A
to the "OFF" position.
Back Flush
1. Disconnect both hoses from the oil cooler pipes and then
connect them to the opposite oil cooler pipe. This will
allow the oil cooler and pipes to be back flushed.
2. Repeat steps 3 and 4 of the "INITIAL FLUSH" procedure.
3. Release the trigger of J–35944-A and allow water only to
rinse the oil cooler and pipes for one minute.
4. Turn the water valve on J–35944-A to the "OFF" position
and turn "OFF" the water supply at the faucet.
5. Attach the air supply to the air valve on J–35944-A and
blow out the water from the oil cooler and pipes. Continue
until no water comes out of the discharge hose.
Flow Check
1. Disconnect both hoses from the oil cooler pipes. Connect
the oil cooler feed pipe to the transmission and the return
pipe to the discharge hose. Clip the discharge hose onto
the oil drain container.
2. Confirm the transmission is filled with automatic
transmission fluid.
3. Start the engine with the transmission in "PARK" range
and run until automatic transmission fluid begins to flow
into the oil drain container. Turn off engine, empty oil
drain container and fill transmission with automatic
transmission fluid. Start the engine with the transmission
in "PARK" range and run for 30 seconds. A minimum of
two quarts (1.9 L) must be discharged during this 30
second run time.
If fluid flow is equal to or greater than 2 qt. in 30 seconds,
go to step 4.
If fluid flow is less than 2 qt. in 30 seconds, perform the
following diagnosis:
• Disconnect the oil cooler feed line at the radiator. Con-
nect the discharge hose to the oil cooler feed line. Clip
the discharge hose onto the empty oil drain container.
Start the engine with the transmission in "PARK" range
and run for 30 seconds. A minimum of two quarts (1.9
L) must be discharged during this 30 second run time.
Do the following according to the flow rate:
Insufficient feed flow:
• Inspect the transmission for leaks or blockage.
Sufficient feed flow:
• Inspect the oil cooler return pipe and the oil cooler for
blockages or leaks.
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