Fluid in Spark Plug Tubes

A Check Engine light may be illuminated with misfire DTCs set, or a possible oil or coolant leak may be found, on some 2010-2013 Enclave, LaCrosse, CTS, SRX, Camaro, Equinox, Traverse, Acadia, Terrain; 2012-2013 Caprice PPV, Captiva, Impala; 2013 ATS and XTS models equipped with 3.0L and 3.6L (RPOs LF1, LFW, LLT, LFX) HFV6 engines. (Fig. 10)


Fig 10


On inspection, coolant or oil may be found in a spark plug tube. Determine if the oil or coolant is coming from the spark plug tube and not leaking into it from above. If the spark plug tube is leaking, replace the cylinder head, spark plug and coil.


Porous spots in the head created during manufacturing cause the leak. The spark plug tubes are permanently sealed into the head and are not replaceable.


If a cylinder head is replaced for this condition, mark the faulty spark plug tube before sending the head in for warranty or core so GM Engineering or the re-manufacturing facility can identify it.


– Thanks to Aron Wilson

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