Hydrolocking is the event that happens when more liquid exists in a cylinder than the volume that exists above the piston.

When the piston is driven up the liquid stops it as the liquid is NOT compressable. If enough force is applied spomething breaks as the liquid will not compress.

The most common hydro lock is from head gaskets leaking coolant into the cylinder. I have seen oil and gas hydrolocks also. And I have even seen a ch126 300SD driven in a puddle till the bow wave entered the intake and hydrolocked bending a coupe connecting rods.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician