Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 192 (AUTOMATIC TRANSAXLE SERVICING)LUBRICATIONOIL COOLER FLUSHING & FLOW TESTBACK FLUSH
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Back Flush
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Back Flush
WARNING: This page is about a different car, the 2003 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
- Inspect the transaxle oil cooler pipes for kinks or damage. Repair as necessary.
- Connect the transaxle oil cooler and line flusher to the oil cooler feed top connector. Use Cooler Flusher Adapter (J 35944-440).
- Clip the discharge hose (5) onto the oil drain container. See Figure .
- Attach the transaxle oil cooler and line flusher to the undercarriage of the vehicle with the hook provided and connect the flushing system feed supply hose (3) from the transaxle oil cooler and line flusher to the bottom connector oil cooler return pipe. Use Cooler Flusher Adapter (J 35944-440).
- Turn the transaxle oil cooler and line 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 transaxle fluid. See Figure . 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.
- Turn the transaxle oil cooler and line flusher water supply valve (1) to the OFF position and clip the discharge hose onto a 5 gallon (19L) pail with a lid, to avoid splashback. See Figure
.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 a bucket or similar container.
- Turn the transaxle oil cooler and line 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. The discharge will foam vigorously when the solution is introduced into the water stream. See Figure and Figure .
- Flush the oil cooler and pipes with water and solution for 2 minutes. During this flush, attach the shop air supply 120 psi (825 kPa) to the flushing system feed air valve (2) located on the transaxle oil cooler and line flusher, for 3-5 seconds at the end of every 15-20 second interval to create a surging action. See Figure .
- Release the trigger (8) and turn the transaxle oil cooler and line flusher water supply valve (1) to the OFF position. See Figure and Figure .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.