If a fluid leak is found underneath a 2007-2009 Silverado or Sierra - equipped with transfer case RPO codes NQF or NQG and a 6L90 automatic transmission, RPO code MYD, the transfer case fluid may be leaking out of the adapter area between the transfer case and the transmission.
The transfer case input seal in these models is a double lip design and these transmission/transfer case combinations use a dry cavity adapter area. Because this is a dry cavity area, the seal can overheat, which may cause a fluid leak that may be misdiagnosed as an adapter gasket leak.
After verifying the condition, replace the double lip seal with a single lip seal (part number 19133156). The single lip seal will run cooler and be less prone to leakage.
IMPORTANT: The double lip seal will continue to be used with 4-speed automatic transmissions and wet transfer case adapter cavities. Failure to use a double lip seal in vehicles with 4-speed transmissions will result in a leak.
- Thanks to Chuck Krepp
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