Automatic Transmission Servicing: Maintenance Chevrolet TrailBlazer I

SERVICE INTERVALS

Change the ATF and filter every 50,000 miles if the vehicle is mainly driven under one or more of these conditions

1. In heavy traffic where the outside temperature regularly reaches 90°F (32°C) or higher.
2. In hilly or mountainous terrain.
3. When doing frequent towing.
4. Uses such as found in taxi, police or delivery service.

If the vehicle is not used under any of these conditions, change the fluid and filter every 100,000 miles.

CHECKING FLUID LEVEL & CONDITION

Note. The transmission fluid may darken with normal use and does not always indicate contamination or oxidation.

1. Start the engine and operate the vehicle for 15 minutes or until the transmission fluid reaches an operating temperature of 180-200°F (82-93°C). Park the vehicle on a level surface. With your foot on the brake, move the shift lever through each gear range. Pause for about 3 seconds in each range, ending in Park. Apply the parking brake and let the engine idle for 3 minutes. Remove the transmission fluid level indicator. Wipe the indicator clean. Reinsert the indicator. Give the indicator a full twist in order to close. Wait 3 seconds and remove the indicator. Read both sides of the indicator. The fluid must be within the hot cross-hatched area using the lowest level reading.
2. Check the fluid color. Is the fluid Red in color? If so, go to step 6 . If not, go to next step.
3. Is the fluid a non-transparent Pink in color? If so, go to step 15 . If not, go to next step.
4. Is the fluid a Light Brown in color? If so, go to next step. If not, go to step 6 .
5. Is the fluid Black in color and or have a burnt smell? If so, go to step 15 . If not, go to next step.
6. Does the fluid appear as a solid liquid and not foamy or full of bubbles on level indicator? If so, go to next step. If not, go to step 8 .
7. Check the fluid level. Proper level should be in middle of the "X" pattern, on level indicator. Is the level okay? If so, go to step 20 . If not, go to next step.
8. Is the fluid level high on indicator? If so, go to step 13 . If not, go to next step.
9. Is the fluid level low on indicator? If so, go to next step. If not, go to step 5 .
10. Check for any external leak or leaks. Did you find an external leak or leaks? If so, go to next step. If not, go to step 12 .
11. Correct leak or leaks as needed. Are any leak or leaks still present? If so, go to step 10 . If not, go to next step.
12. Add fluid until level is in middle of "X" pattern on the level indicator. Is the level okay? If so, go to step 20 . If not, go to step 7 .
13. Drain fluid until level is in middle of "X" pattern on the level indicator. Is level okay? If so, go to step 20 . If not, go to step 7 .
14. Replace oil cooler and flush lines. See «OIL COOLER LINES»(ref-154782-S03973626202003052300000) under REMOVAL & INSTALLATION. Is the replacement complete? If so, go to step 16 .
15. Drain fluid and remove oil pan to inspect. See «DRAINING & REFILLING»(ref-154782-S23228125912003052300000) . Is there sign or signs of internal component damage noted in bottom of transmission oil pan? If so, go to step 17 . If not, go to step 14 .
16. Replace the filter and fluid. See «DRAINING & REFILLING»(ref-154782-S23228125912003052300000) . Is the replacement complete? If so, go to step 7 .
17. Flush oil cooler and lines. See «OIL COOLER FLUSHING»(ref-154782-S42744730542003052300000) and «TRANSMISSION & OIL COOLER FLOW CHECK»(ref-154782-S31767179682003052300000) . Is oil cooler flushing and flow test complete? If so, go to next step.
18. Overhaul transmission. See appropriate OVERHAUL article. Is the overhaul procedure complete? If so, go to next step.
19. Add new fluid. Is the procedure complete? If so, go to step 7 .
20. Check the fluid level and correct as necessary. Is the fluid level satisfactory? If so, system is okay. If not, go to step 1 .

RECOMMENDED FLUIDS

Manufacturer recommends DEXRON-III(R) ATF.

Draining

1. Raise and support vehicle.
2. Place a drain pan under the transmission oil pan.
3. Remove the oil pan drain plug, if equipped.
4. If necessary, remove the bolts and position aside the shift cable bracket for clearance while lowering the pan. It is not necessary to remove the shift cable from the lever or bracket.
5. Remove the oil pan bolts from the front and sides of the pan only.
6. Loosen the rear oil pan bolts approximately 4 turns.
7. Lightly tap the oil pan with a rubber mallet in order to loosen the pan to allow the fluid to drain.
8. Remove the remaining oil pan bolts.
9. Remove the oil pan and the gasket.
10. Grasp firmly while pulling down with a twisting motion in order to remove the filter. (Scheme 81)
11. Remove the filter seal. The filter seal may be stuck in the pump; if necessary, carefully use pliers or another suitable tool to remove the seal. (Scheme 82) Discard the seal.
12. Inspect the fluid color.
13. Inspect the filter. Pry the metal crimping away from the top of the filter and pull apart. The filter may contain the following evidence for root cause diagnosis: Clutch material. Bronze slivers indicating bushing wear. Steel particles.
14. Clean the transmission case and the oil pan gasket surfaces with solvent, and air dry. You must remove all traces of the old gasket material.

Scheme 81

Scheme 82

Refilling

1. Coat the new filter seal with automatic transmission fluid.
2. Install the new filter seal into the transmission case. Tap the seal into place using a suitable size socket. (Scheme 83)
3. Install the new filter into the case.
4. Install the oil pan and a new gasket.
5. Install the oil pan bolts. Tighten the oil pan bolts alternately and evenly to specification. See «TORQUE SPECIFICATIONS»(ref-154782-S37141348322003052300000).
6. If previously removed, install the shift cable bracket and bolts. Tighten the bolts to specification. See «TORQUE SPECIFICATIONS»(ref-154782-S37141348322003052300000).
7. Apply a small amount of sealant to the threads of the oil pan drain plug, if equipped.
8. Install the oil pan drain plug, if equipped. Tighten the oil pan drain plug to specification. See «TORQUE SPECIFICATIONS»(ref-154782-S37141348322003052300000).
9. Lower the vehicle.
10. Fill transmission with appropriate fluid to proper level. See «RECOMMENDED FLUIDS»(ref-154782-S04582642872003052300000) and «FLUID CAPACITIES»(ref-154782-S30874031262003052300000).
11. Check the COLD fluid level reading for initial fill only.
12. Inspect the oil pan gasket for leaks.

Scheme 83

OIL COOLER FLUSHING

Note. DO NOT use solutions that contain alcohol or glycol. Use of solutions that contain alcohol or glycol may damage flushing equipment, oil cooler components and/or transmission components.

Back Flush

1. Inspect the transmission oil cooler pipes for kinks or damage. Repair as necessary.
2. Connect the transmission oil cooler and line flusher to the oil cooler feed bottom connector. Use the Cooler Flushing Adapter (J-35944-200), if required.
3. Clip the discharge hose (5) onto the oil drain container. (Scheme 84)
4. Attach the line flusher to the undercarriage of the vehicle with the hook provided and connect the flushing system feed supply hose (3) from the line flusher to the top connector oil cooler return pipe. Use the cooler flushing adapter, if required.
5. Turn the flusher water supply valve (1) to the ON position and allow water to flow through the oil cooler and pipes for 10 seconds to remove any remaining transmission 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. Continue with the cooler flushing and flow check procedure once the blockage is corrected.
6. Turn the flusher water supply valve (1) to the OFF position and clip the discharge hose (5) onto an appropriate container with a lid, to avoid splashback. NOTE: Flushing for approximately 2 minutes in each cooler line direction will result in a total of about 8-10 gallons of waste fluid. This mixture of water and flushing fluid is to be captured in an appropriate container for proper disposal.
7. Turn the flusher water supply valve (1) to the ON position and depress the trigger (8) to mix cooler flushing solution into the water flow. Use the clip provided on the handle to hold the trigger (8) down. (Scheme 85) The discharge will foam vigorously when the solution is introduced into the water stream.
8. Flush the oil cooler and pipes with water and solution for 2 minutes. During this flush, attach the shop air supply of 120 psi (825 kPa) to the flushing system feed air valve (2) located on the flusher for 3-5 seconds at the end of every 15-20 second interval to create a surging action.
9. Release the trigger (8) and turn the flusher water supply valve (1) to the OFF position.

Scheme 84

Scheme 85

Forward Flush

1. Disconnect both hoses from the oil cooler pipes and then connect them to the opposite oil cooler pipe. (Scheme 84) This will allow the oil cooler and pipes to be back flushed.
2. Repeat steps 6 and 7 of the BACK FLUSH procedure.
3. Release the trigger (8) of the flusher and allow water only to rinse the oil cooler and pipes for one minute. (Scheme 85)
4. Turn the flusher water supply valve (1) to the OFF position and turn OFF the water supply at the faucet.
5. Attach the shop air supply to the flushing system feed air valve (2) on the flusher, and blow out the water from the oil cooler and pipes. Continue until no water comes out of the discharge hose (5).