Water getting into Port Side Cylinders Only

[bossman900]

Rebuilt 350 mercruiser never been in the water only started on muffs. What would cause water to be getting into the cylinders on the port side only? Exhaust manifolds are new but never replaced the risers. Could this be the problem or is it a head gasket issue?

 

[Don S]

Re: Water getting into Port Side Cylinders Only

but never replaced the risers.

Probably the gasket surface of the risers are gone, then it won't seal. Could also be faulty gasket surface on the manifold. Is it a GLM by any chance?
Head gaskets don't usually go bad on all 4 cylinders.