I've got a 91 4runner with the 3.0 and I took it through a deep hole the other day. It bogged down and went dead as soon as I hit it and now wont turn over. It sucked a little bit of water in the motor but not much. I can put a socket on the pulley and turn the motor over as far as I want backwards but as soon as start to turn it forwards it turns maybe half a turn and wont go no farther. I'd really appreciate if anybody had an idea of what might have happened. By the way I have already tried pulling the plugs and turning it over.

 

sounds like you spun a bearing or broke a rod and it locks up. Ive seen that happen many times. Pull the oil pan to confirm it

 

Broken rod. 100% sure.

Same problem happened to my uncle, tho he had a Solara instead of a truck. Would go all day backwards, but would lock up forwards.

 

x2.

But just for fun pull the plugs and see if it turns over. Maybe you got lucky and it just hydrolocked the motor without breaking a rod. Worth a shot.