Technical Service Bulletins

Coolant in GM transmission oil

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If coolant has entered the transmission (as a result of cross-contamination from the transmission cooler and radiator or other reason), GM issued a bulletin that affects 2000-2010 GM passenger cars and light trucks, 2003-2009 Hummer H2, 2006-2009 Hummer H3 and 2005-2009 Saab vehicles with automatic transmission.

Indications of water/ethylene glycol in the ATF may include:

  • ATF blowing out of the transmission vent tube.
  • ATF may appear cloudy, or in extreme contamination, have the appearance of a strawberry milkshake.
  • Visible water in the transmission oil pan.
  • A milky white substance inside the pan area.
  • Spacer plate gaskets that appear to have been glued to the valve body face or case.
  • Spacer plate gaskets that appear to be swollen or wrinkled in areas where they are not compressed.
  • Rust on internal transmission iron/steel components.

If water/coolant has been found in the ATF and the source of the water entry has not been identified, or if a leaking in-radiator transmission oil cooler is suspected (with no evidence of cross-contamination in the coolant recovery reservoir), a simple and quick test kit is available that detects the presence of ethylene glycol in ATF.

The “Gly-Tek” test kit, available from the Nelco Co., should be obtained and the ATF should be tested to make an accurate decision of the need for radiator replacement. This can help to prevent customer comebacks if the in-radiator transmission oil cooler is leaking and reduce repair expenses by avoiding radiator replacement if the cooler is not leaking.

These test kits can be obtained from the Nelco Co., 1047 McKnight Rd. South, Saint Paul, MN 55119. Nelco’s phone number is (651) 738-2014. Their e-mail address is Nelco’s Web address is

One test kit will complete 10 individual fluid sample tests.

Important: If water/coolant is found in the transmission, the following components MUST be replaced:

  • All rubber-type seals
  • All composition-faced clutch plates and/or bands
  • All nylon parts
  • Torque converter

Also, thoroughly clean and rebuild the transmission, using new gaskets and filter. Flush and check the transmission oil cooler using automatic transmission oil cooler flush and flow test essential tool J45096.

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