Don't pull the water manifold off yet, I don't think you will see anything. Pull the oil pan off and pressurize the cooling system. Maybe you could borrow a cooling system pressurize kit from a truck shop. The 2394 will have the larger radiator cap so you will need the large adapter. My moneys on leaking sleeve o rings also. Make note of where the coolant is running from....on the inside of the sleeve or the outside? If the tractor doesn't have a water filter kit on it put one on.