Oil bubbling from spark plug hole after head gasket replacement

[StinkinRenken85]

Happy new year. 84 mercruiser 3.0 140 I had water leaked in with my oil and replaced my head gasket the gasket seemed bad.flushed the motor with diesel fuel a couple times and changed the oil. Have been running in the driveway and the oil has looked good and motor running better. Took it to the water and left it on the trailer and started it up and after it warmed up noticed oil bubbling from my third cylinder spark plug hole. I had taken the head to a good machine shop and they said it was good no cracks. Does this mean the third cylinder is cracked or could there still just be left over junk in the engine that didn’t present itself until after it was under load? Have put a lot of work in this boat really hoping the motor isn’t bad...thanks for any and all hope and advice.

 

[Scott Danforth]

most likely you have a valve cover gasket leak, dripping oil to the plug and your plug isnt tight

because if you have oil bubbling up from around the spark plug, you have serious engine problems.

 

[StinkinRenken85]

Hey Scott thanks for your reply. I think everything is ok. It maybe exactly what you are saying oil that leaked into the cylinder from a when I ran the motor without the valve cover at all while adjusting my rockers. The plugs were loose. Either that or my oil was so thin because I was running sae 30 and I think my manual calls for 40 since I’m in south Florida and the avg temp is way above 50 degrees. Also after flushing my motor with diesel I didn’t get all of it out I don’t think and maybe that thinned my oil enough to cause blow by...I tightened the plugs and changed the oil to 40 grade and so far no issue. Also sounds like the motor is running stronger on the thicker oil. I will have to put it back on the water to see if anything else pops up. You guys at i boats are great thanks for your help on this one and on other questions this year here on my 1st project boat. I may have all the kinks worked out keeping my fingers crossed hoping I don’t need to ask so many questions this new year. Happy new year!

 

[aimlow]

This doesn't make sense. There is no way oil gets around a spark plug unless it leaks externally, or the cylinder is so bad liquid oil is filling the combustion chamber (which I've never seen). 30 wt vs. 40 wt. is absolutely a non-issue.