Some owners of 2021 and 2022 model-year full-size GM truck and SUV models may notice a thick pink liquid forming in their vehicle’s coolant tank that looks a bit like a strawberry milkshake. This is no sweet treat, though, and could be a sign that the engine coolant in the vehicle has been inadvertently mixed with the transmission fluid.
This problem can be traced back to an internal leak in the automatic transmission fluid cooling exchanger, according to a recent post published via GM’s Techlink service site, which may allow transmission fluid to mix with the engine coolant. The cooling exchanger leak may result in a discolored engine coolant “with a strawberry milkshake appearance in the coolant reservoir,” GM says. If this happens, the coolant reservoir may also become overfilled to the point where the coolant is expelled from the overflow.
In addition, the engine may experience an overheating condition due to the lack of proper coolant, while there may also be possible degraded transmission performance, including a shudder and/or vibration. The driver information center may also indicate that the transmission fluid level is very low.
GM technicians are instructed to perform the repairs listed in Bulletin #08-07-30-035, which includes a transmission disassembly and the replacement of the automatic transmission fluid cooling exchanger. Technicians will also flush and replace the engine coolant system to remove the contaminated engine coolant.
This problem may affect certain examples of the 2021 and 2022 model-year full-size GM truck and SUV models equipped with either the turbocharged 2.7L I4 L3B gasoline engine or the 3.0L I6 LM2 turbo-diesel Duramax, and either the GM 10L80 ten-speed automatic transmission or GM 8L90 eight-speed automatic transmission. The following models are affected:
- Cadillac Escalade
- Cadillac Escalade ESV
- Chevy Silverado
- Chevy Tahoe
- Chevy Suburban
- GMC Sierra
- GMC Yukon
- GMC Yukon XL
GM has not issued a recall for this issue. Customers experiencing this problem should contact their dealership to have the above-mentioned repairs performed from Bulletin #08-07-30-035.