What could be the reasons why I am not getting any compression in one of the cylinders on my 135hp mercury outboard? Whats the worst it could be? could it be something simple like head gasket?
Sounds like something Major. I would pull the head off to inspect for obvious damage. If you pulled the plug out and noticed some silver powder on it (aluminum), it is most likely major, and there are many different levels of MAJOR. All of which are money. If it is zero compression, I feel it is too late. Pull the head and look.
