Clemson has a point the guy may not back out though. Unless he is selling as is rather than running then you always can turn it with a socket and then take it home and start it so he doesn't feel so bad about it.
I would turn with a big socket, but honestly at $10/100 for steel if you wanted to scrap it you could get $200 then sell the tires for $300 and you would have your money back, but even if engine is locked up i think you could part it out and make $$. The head alone if not blown must be worth a few hundred, and on and on.
And If I crank it on site he might want more..so ima take my chances, if water was in it the oil would be contaminated no? Its not at all, neither is trans fluid. If its more then I am capable of doing to get it running it can be bought for same price from me.
Smoody buy it. If you seriously want i will go in halfs with you if your thinking of flipping it? It will lessen your risk. I dont think you can go wrong even if it has a cracked block!!
But the oil would only have water in it if there is a crack in the block or the head is maybe blown.
The nut on the crank is inside the crank pully or the lower pully that is mounted to the engine. This is the pully that turns the belt to spin all the other pulleys. I have no idea the size nut but will probly be around an inch to 1.5 inches?? YOu can put a socket on it and an extention to get outside the pulley diameter and turn it either way with a ratchet (preferably the way the motor turns) if it move with just compression force, easy for half a turn then hard then easy, this will mean A its not locked up and B that it has some form of compression.
Pull the compression release it will spin easy the bolt on the crank may be a tight fit a breaker bar and just the right socket would do it. I dont know the size sorry maybe look at your other one first and try it on it before going over there.
If it moves even a little with no effort it is not locked up so a complete round I dont feel is necessary make it easy on you fwtw.
But yeah at that price you should just go buy it and then mess with it. I wouldn't think twice about it fact it may get away from ya if you dont jump now!