T&T: Engine mount diagnosis

[Paul Brannon]

How does one go about determining whether engine mounts are bad?  I have a
vibration (it seems to be predominately on one side) and I have had the props
reworked and shafts checked during a haul out last year.  I later replaced one
damper plate and have checked alignment a few times.  There seems to be
excessive fore & aft movement of the engine under loading as the PSS shaft
seal will at times leak at high loading and I can actually see the engine
oscillating somewhat in time with the vibration.  I thought at first that the
prop was not properly tuned but since I saw the leaking seal and the apparent
extension of the bellows, I began to consider the engine mounts.  I have not
actually measured the amount of movement of the engine at this time but I may
once we get underway again.  What is considered "normal" if there is such a
thing and how do I determine the integrity of the mounts short of just
replacing?

Thanks,
Paul & Stacy Brannon
m/v SEASEA
1978 Gulfstar 44 MC