Coolant in Spark Plug Tube
This bulletin applies to GM vehicles equipped with HFV6 engines (3.0L and 3.6L LF1, LFW, LLT and LFX). Affected vehicles include 2010-2014 Buick Enclave and LaCrosse, Cadillac ATS, CTS, SRX and XTS, Chevy Camaro, Caprice, Equinox, Impala and Traverse and GMC Acadia and Terrain.
The SES light may be on, with misfire codes or possible coolant leak. Upon inspection you may find evidence of coolant or oil in a spark plug tube. Determine if the fluid is coming from the spark plug tubes and not leaking into the tube from above. If the spark plug tube(s) is leaking, replace the cylinder head, spark plug and coil.
The leaks are caused by porous spots in the head created during manufacturing and are not field-repairable.
The spark plug tubes are permanently sealed in the cylinder head and are not replaceable.