How Do You No Your Car Engine As Gone?

When it won't turn over and it's locked up. Now if the engine is locked up you won't be able to turn the crankshaft. Check your oil and see if you have a milky color that will indicate water in your engine if you have oil in it .  No oil"' will lock it up also  , and that's some of the ways to know that your engine is gone . If you ride with a blown head gasket for long that's what will turn your oil and water milky.
Now a lot of the new school normally go out when you are over 250,000 miles on them or more.