A little story for you.
A new dredger was being built with two little CAT engines, 1500kw, gearbox to shaft at the aft of each engine and a large alternator coupled to the fwd end.
The engine is on resilient / rubber mountings.
All parts were aligned, and signed of by all interested parties.
The engine was prepared for trials.
When the engine was run there was heavy vibration, mainly at the forward end.
It turned out, the piping system on the engine holds most of the 1,5 tonnes of water at the fwd end of the engine, this changed the alignment, dropping the fwd end and lifting the aft end.
The CW system was only filled just before the trials.
I would have assumed, for the sake of alignment, the fluids in an engine were fairly evenly balanced, apparently not.