He eventually discovers the death of this engine may have been caused by a faulty component in the crankshaft assembly.
After removing the cylinder head, he discovered rust in the cylinders themselves, along with incorrect piston positioning. Cylinders one, two, and three were at the bottom of their strokes, and cylinder four at the top. A further investigation revealed chunks of metal in the oil pan, and after removing the crankshaft, Eric saw a broken connecting rod and several impact marks in the cylinder wall.
Eric concluded the engine failed because of hydrolock, a condition where water enters the engine. Since liquid is incompressible, when the piston tries to engage its compression stroke, the next weakest link buckles, which in this case is the conrod.
Not even legendary Toyota reliability can withstand hydrolocking, and it’s a lesson we’ve learned before with a 4Runner as to why water and engines do not mix.