Transmission Fluid Cooler Flushing and Flow Test
Table 1: Minimum Flow Rate in
Gallons Per Minute (gpm)
GM studies indicate that plugged or restricted transmission oil
coolers and pipes cause insufficient transmission lubrication and
elevated operating temperatures which can lead to premature
transmission failure. Many repeat repair cases could have been
prevented by following published procedures for transmission oil
cooler flushing and flow checking. This procedure includes flow
checking and flushing the auxiliary transmission oil cooler, if
equipped.
Note: Use the
DT-45096 flush and flow test tool or equivalent to
flush and flow test the transmission oil cooler and the oil cooler
pipes after the transaxle is removed for repairs.
Only GM Goodwrench DEXRON®VI automatic transmission fluid
should be used when doing a repair on a GM transmission.
Time allowance for performing the cooler flow checking and
flushing procedure has been included in the appropriate labor time
guide operations since the 1987 model year. The service procedure
steps for oil cooler flushing and flow testing are as follows:
Cooler Flow Check and Flushing Steps
2. |
Determine Minimum Flow
Rate |
6. |
Code Recording
Procedure |
Special Tools
• |
DT-45096
Transmission Oil Cooling System Flush and Flow Test Tool
|
• |
DT-45096-50
Transmission Cooler Flush Adapter |
• |
Shop air supply with water/oil
filters, regulator and pressure gauge - minimum 90 psi |
For equivalent regional tools, refer to
Special Tools .
Machine Set-up
1. |
Verify that the main power
switch (1) is in the OFF position. |
2. |
Place the main function switch
(2) in the IDLE position. |
3. |
Connect DT-45096
flush and flow test tool to the vehicle 12V DC power source
by connecting the red battery clip to the positive, +, battery post
on the vehicle and connect the negative lead to a known good
chassis ground. |
4. |
Turn the main power switch to
the ON position. |
|
Caution: Do
not overfill the supply vessel. Damage to the unit may result. To
verify the fluid level, view the LCD screen display while filling
the unit, to ensure the fluid level does not exceed 30 L (32
qt). |
5. |
Fill the supply tank with
Dexron®VI through the fill port. |
6. |
Reinstall and tighten the fill
cap. |
7. |
Connect a shop air supply hose
to the quick-disconnect on the rear panel marked SUPPLY AIR.
|
Determine Minimum Flow Rate
1. |
From the machine display,
identify the temperature of the automatic transmission fluid that
is stored in the supply vessel of DT-45096 flush
and flow test tool . |
2. |
Determine whether the
transmission oil cooler is steel or aluminum by using a magnet (1)
at the cooler flange (2) at the radiator. |
3. |
Refer to the table below.
Using the temperature from step 1, locate on either the Steel
MINIMUM Flow Rate table or the Aluminum MINIMUM Flow Rate table the
minimum flow rate in gallons per minutes (GPM). Record the minimum
flow rate in GPMs and the supply fluid temperature for further
reference. |
Example
|
• |
Fluid temperature:
75°F |
|
• |
The MINIMUM flow rate for this
example would be 0.8 GPM. |
4. |
Inspect transmission oil
cooler lines for damage or kinks that could cause restricted oil
flow. Repair as needed and refer to the appropriate GM service
manual procedures. |
Minimum Flow Rate in Gallons Per Minute (gpm)
Temperature Range
|
Steel
|
Aluminum
|
65 - 66°F
|
0.6 gpm
|
0.5 gpm
|
67 - 70°F
|
0.7 gpm
|
0.6 gpm
|
71 - 75°F
|
0.8 gpm
|
0.7 gpm
|
76 - 80°F
|
0.9 gpm
|
0.8 gpm
|
81 - 84°F
|
1.0 gpm
|
0.9 gpm
|
85 - 89°F
|
1.1 gpm
|
1.0 gpm
|
90 - 94°F
|
1.2 gpm
|
1.1 gpm
|
95 - 98°F
|
1.3 gpm
|
1.2 gpm
|
99 - 103°F
|
1.4 gpm
|
1.3 gpm
|
104 - 108°F
|
1.5 gpm
|
1.4 gpm
|
109 - 112°F
|
1.6 gpm
|
1.5 gpm
|
113 - 117°F
|
1.7 gpm
|
1.6 gpm
|
118 - 120°F
|
1.8 gpm
|
1.7 gpm
|
|
|
Back Flush Procedure
1. |
Connect the
DT-45096-50 cooler flush adapter (1) to the vehicle
transmission oil cooler supply and return lines at the
transmission. |
2. |
Connect the black supply hose
(1) to the return line, top connector of the transmission, and the
clear waste hose (2) to the feed line, bottom connector of the
transmission, to the vehicle cooler lines. This is the reverse flow
- backflush direction. |
3. |
Turn the main function switch
to the FLUSH position. Allow the machine to operate for 30
seconds. |
4. |
Turn the main function switch
to the IDLE position and allow the supply vessel pressure to
dissipate. |
Forward Flush
1. |
Disconnect the supply and
waste hoses from the vehicle cooler lines. Reverse the supply and
waste hoses to provide a normal flow direction. |
2. |
Turn the main function switch
to the FLUSH position and allow machine to operate for 30
seconds. |
Flow Test
|
Note: If the flow
rate is less than 0.5 gpm, the LCD displays an error message. Refer
to the Troubleshooting section of the operation manual.
|
1. |
Turn the main function switch
to the FLOW position and allow the oil to flow for 15 seconds.
Observe and note the flow rate; this is the TESTED flow
rate. |
2. |
Compare the TESTED flow rate
to the MINIMUM flow rate information previously recorded.
|
|
• |
If the TESTED flow rate is
equal to or greater than the MINIMUM flow rate recorded, the oil
cooling system is functioning properly. Perform Code Recording
Procedure. |
|
• |
If the TESTED flow rate is
less than the MINIMUM flow rate previously recorded, repeat the
back flush and forward flush procedures. |
3. |
If the TESTED flow rate is
less than the MINIMUM flow rate after the second test, perform Code
Recording Procedure. |
|
3.1 |
Replace the transmission oil
cooler. |
|
3.2 |
Reconnect supply and waste
hoses to the cooler lines in the normal flow direction. Perform
Flow Test. |
|
3.3 |
Perform Code Recording
Procedure. |
Code Recording Procedure
1. |
Turn the main function switch
to the CODE position. |
|
Note:
• |
If power is
interrupted prior to the recording of the seven-character code, the
code will be lost and the flow rate test will need to be
repeated. |
• |
The flow test must
run for a minimum of 8-10 seconds and be above 0.5 GPM for a code
to be generated. |
|
2. |
Record TESTED flow rate,
temperature, cycle and seven-character flow code information on
repair order. |
Clean-up
1. |
Turn the main function switch
(2) to the IDLE position and allow the supply vessel pressure to
dissipate. |
2. |
Turn the main power switch (1)
to the OFF position. |
|
Note: A small amount
of water may drain from the bottom of the unit when the air supply
is disconnected. This is a normal operation of the built-in water
separator.
|
3. |
Disconnect the supply and
waste hoses and the 12-volt power source from the vehicle.
|
4. |
Disconnect the air supply hose
from DT-45096 flush and flow test tool .
|
5. |
Dispose of the waste ATF in
accordance with all applicable federal, state, and local
requirements. |
|