In early 80s there was a movie I saw I just remember a few parts ?

In the movie a few kids were stuck in a haunted house in a secret passage under a fire place. They were looking for buried treasure, at the end a ghost helps them escape he was a old man with a white beard. I think it was a movie that would come on sometimes on Saturday afternoons after cartoons back in the day I was 4 or 5 I'm 31 now can anyone help. It bugs me that I can't find it help please