Oil Cooler Flushing & Flow Test: Preparation

1999 GMC Forward Control 5.7 R, AutomaticSECTION Preparation
WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
  1. After the repair or replacement transaxle is installed in the vehicle, do not reconnect the oil cooler pipes.
  2. Remove the fill cap (9) on the Transmission Oil Cooler and Line Flusher (J-35944-A) and fill the flusher tank (4) with 20 oz. (0.6L) of flushing fluid using the measuring cup (6). Do not overfill. Install the fill cap (9) on the transmission oil cooler and line flusher and pressurize the flusher tank (4) to 80-100 psi, using the shop air supply at the tank air valve (9). See Fig 1 .
  3. Connect the transmission oil cooler and line flusher discharge hose (5) to the oil cooler return pipe (top connector). Clip the discharge hose (5) onto the oil drain container. Attach the transmission 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 transmission oil cooler and line flusher to the oil cooler feed pipe (bottom connector).
  4. With the water supply valve (1) on the transmission oil cooler and line flusher in the OFF position, connect the water supply hose (7) from the transmission oil cooler and line flusher to the water supply at the faucet. See Fig 1 and Fig 2 . Turn on the water supply at the faucet.
Fig 1: Identifying Flushing Equipment
G00056982Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

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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.