What causes a rod to go through an engine block?

Answer 1

I have just pushed a con rod through a marine diesel engine. From what I have found out, it is possibly from low lube oil, but that whould probably only cause wear, and eventually a cracked big end, possibly a bent rod. However, to push through the crank case it is more likely water inside the cylinder. In my case, I work on a yacht that has had a small generator for five years, but it is not big enough to expell water quick enough, because the exhaust system was designed for a bigger engine. Also, since it is a sailing yacht, we have a high u-bend after the engine to prevent water siphoning back. The little water pump/low pressure of the small engine is not enough to expell it, causing bad back pressure. over the years, this has caused many problems, most importantly, constant light smoke. Also, the fibreglass mixer and seperator boxes are cracked and leaking from overheating. I believe that the engine finally got to a point where the backpressure was too great (combination of age, sea strainer condition, load of engine, blockages builing up in water outlet etc) and the water backed all the way to the exhaust gas pipe and back into the cylinders.