Mercury 2012 115 pro xs

[sbryant531]

My 2012 115 hp pro xs Mercury has a compression of 45 on the third cylinder 125 compression on cylinders one and two I currently have it soaking in sea foam deep creep. I have ordered a borescope which should arrive today so that I can look inside the cylinder at the cylinder walls and piston for any possible damage with a C phone. I am hoping that if I do have stuck to the rings that this will freeze them do you guys think that I will have to do a rebuild on this and remove the powerhead from the engine?

 

[boscoe]

Unless the compression gauge suffered a temporary fault, or it is just a gasket problem, I am seeing a major repair in your future.

Next step might be a differential (aka leak down) pressure test to determine what specifically is causing the lack of compression pressure.