Flow Check

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Flow Check
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Connecting Return Pipe, Horizontal/Bottom Connector To Discharge Hose
G03415460Courtesy of GENERAL MOTORS CORP.
  1. Disconnect both hoses from the oil cooler pipes. Connect the oil cooler feed pipe, vertical/top connector, to the transmission and the return pipe, horizontal/bottom connector to the discharge hose (5). Clip the discharge hose (5) onto the empty 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 for 30 seconds. A minimum of 1.9 liters (2 quarts) must be discharged during this 30 second run time.
    • If fluid flow is greater than 1.9 liters (2 quarts) in 30 seconds, proceed to step 4.
    • If fluid flow is less than 1.9 liters (2 quarts) in 30 seconds, perform the following diagnosis:

      Disconnect the oil cooler feed line at the radiator. Connect the discharge hose (5) to the cooler feed line. Clip the discharge hose (5) to the empty oil drain container. Start the engine with the transmission in PARK range and run for 30 seconds. A minimum of 1.9 liters (2 quarts) must be discharged during this 30 second run time. Do the following according to the flow rate:

      • Insufficient feed flow: inspect the transmission
      • Sufficient feed flow: inspect the oil cooler return pipe and the oil cooler and auxiliary cooler, if equipped.
  4. Remove the discharge hose (5), reconnect the cooler feed and return pipes to the transmission and refill the unit to the proper fluid level. Inspect the transmission oil cooler pipe connections at the radiator, the auxiliary cooler if equipped and the transmission for leaks.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.