Transmission Oil Cooler Flow Check and Flush Test

When performing a transmission oil cooler flow check and flush test on the 2003-2010 Vibe, 2002-2007 VUE, 2003-2004 ION and 2008-2009 Astra, essential tool J-45096, Transflow Transmission Cooler Flusher, should be used. (Fig. 3) This procedure applies to both automatic and manual transmissions that do not use DEXRON®-III or DEXRON®-VI transmission fluid.


Fig 3


A plugged or restricted transmission oil cooler and pipes may lead to insufficient transmission lubrication, elevated operating temperatures, and ultimately, premature transmission failure. To prevent this, follow the transmission oil cooler flow check and flush test procedures outlined in the appropriate Service Information and #PI0537.


The procedure involves:

• Machine set-up

• Determining the minimum flow rate

• Back flushing

• Forward flushing

• Flow testing

• Code recording

• Clean up


The J-45096 transmission oil cooling system flush and flow test tool replaces other cooler flushing tools. The J-45096 tool is a self-contained unit using a 12-volt flow meter, shop air supply and DEXRON-VI automatic transmission fluid (ATF).


TIP: Use only DEXRON-VI automatic transmission fluid in the J-45096 tool. While the transmission fluid requirement for the listed vehicles is different than DEXRON-VI, flushing the cooler with DEXRON-VI is an acceptable service procedure. Very little fluid remains in the cooler after the flush procedure and the residual DEXRON-VI ATF in the cooler is compatible with the listed vehicles’ transmission fluid.


When using the tool in the flush mode, ATF is cycled through the transmission oil cooling system. High-pressure air is automatically injected into the fluid stream, adding agitation to the ATF oil, to help remove contaminated oil and debris.


In the flow mode, the electronic flow meter measures the flow capability of the transmission oil cooling system. The display indicates the ATF oil flow rate in gallons per minute (GPM) along with the amount of ATF in the supply vessel, supply vessel ATF temperature, machine cycles and the operating mode. The required minimum ATF oil flow rate reading is directly related to the supply oil temperature.


In the code mode, a random, encrypted code is generated that can be used for verification of flow test results. After completing the flush and flow testing, the testing flow rate (in GPM), temperature, cycle number and seven-digit flow code must be recorded on the repair order.


Current essential cooler line adapters are used to connect the J-45096 to the transmission oil cooler lines, which enables the tool to adapt to most GM passenger cars and light-duty trucks. If an adapter is not available, one can be made using a barbed hose connector and a rubber hose obtained locally.


For information about vehicles with automatic transmissions that use DEXRON-III or DEXRON-VI transmission fluid, refer to Bulletin #02-07-30-052H.


– Thanks to Dave Peacy and Mark Kevnick

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