I would have probably done the same if access was that restricted. Not sure about the V6 but the 2.0D sure is. As it's water you'll most likely get away with it. You wouldn't with something like the head bolts for example. My first car, a 8-valve Escort, I used a cutout from a Weetabix package smeared with grease as a thermostat housing gasket! Now I wouldn't publicly advise doing this but it lasted for years and was still there when I sold the car! 