Starcraft Mercruiser speedometer issues

[zabitac]

The prior owner of this Starcraft Aurora 2015 deck boat says the speedometer hasn't worked in 3 years. Before purchasing the boat, I paid to have the water pump installed in the stern drive. I called the mechanic later to ask if the speedometer worked when he test drove it. He said that he test drove the boat, then replaced the water pump and checked the speedometer by blowing air into the hose at the stern drive. It appeared to be fine. He suggested that he may have left the hose unplugged. I checked the hose plug. It slips on easily, but doesn't seem to lock on. I checked the small hole at the front of the stern drive and it's not clogged. It seems like the speedometer moves slightly sometimes when starting off. I'm too far away now to take it back to the mechanic.I wondered if someone might have an idea of what might be the issue.
Thanks.

 

[NHGuy]

Blow some air into the boat side tube and see if the speedometer moves. If it does, I have heard of folks clearing out debris in the lower drive with air pressure and maybe a bit of physical help such as a pick or long bit of metal in the speedo hole down at the lower front of the drive. Just be cautious to avoid removing paint, etc.

 

[zabitac]

I used a small drill bit to clean the hole in the lower drive out. I thought that since the water pump was just installed, there shouldn't be any debris. All I know is that the hole isn't clogged. The mechanic stated that the speedometer worked when he blew air in from the boat side of the tube.
I wondered how tight the tube is supposed to be that plugs onto the stern drive. It just slips on and doesn't seem to lock into place.

 

[Scott Danforth]

put a zip tie around it like a hose clamp.

 

[Old Ironmaker]

I use my GPS for speedometer. My dash speedo doesn't kick in until 10MPH and I troll as slow as 1.5 MPH. I know it would just bug me not having anything working right on my boat. As Scott suggested just zip tie the hose on, someone must have lost the clamp when they worked on it.

 

[shrew]

The all do this. I, personally, have little interest in fixing an inaccurate speedo just so it 'works'. These use water pressure. There is a hole on the outdrive that goes to a tube all the way to the helm. If you've ever seen one come undone or rupture at the dash end, you'd probably reconsider it as well. If the tube comes undone, then water starts pouring into the inside of the dash, where the fuse blocks are typically located. I boat in saltwater and have no interest in this.

I'm in the process of replacing my transom assembly. My mechanic asked me if the speedo works. My reply "Absolutely not and it better stay that way". He laughed and replied "Good, we're on the same page then".

GPS is WAY more accurate.

 

[zabitac]

I've never had a speedometer hose to rupture and don't use it in salt water. That does make sense though. In my lake, I haven't seen a need for a gps before, but this may be the best solution.
Thanks for the input.