Re: Johnson 5hp TN-28 water pump Home › Forum › Ask A Member › Johnson 5hp TN-28 water pump › Re: Johnson 5hp TN-28 water pump david-bartlettReplies: 1204Topics: 97 July 15, 2018 at 10:33 pm #79626 Alex, There is a “tell-tale on the power head which will indicate water circulating. It is hard to see as it is just a small drilled hole in a brass fitting. Ben Ditmar has a YouTube video of one you can see.