Can Hydrostatic lock (water in cylinders), be relieved by removing the glow plugs and turning over engine or must you remove the injectors?

Anything that gives the incompressable fluid an exit will work, such as a glow plug or injector. I have not had to deal with this personally, but the cost of damage from hydro lock is high! Therefore, I would recommend that you physically check the cylinder for liquid presence and remove any that you can, using a small tube as a siphon. I would also crank the engine by hand through two revolutions (one complete combustion cycle) before using the starter. Good luck

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Deezel
87 300TDT
150,000 miles

How did that much water get into the cylinders? sounds like you've got another type of problem here.