speedometer help

[1986bassbuggy$@]

I bought a 1987 20' bass tracker bass buggy pontoon used and have since added a new motor but the speedometer never worked, checked voltage and 12v across the board, but what is inside the small vacuum looking line going to the back of the boat?

 

[1986bassbuggy$@]

Re: speedometer help

maybe i should word this diffrently how does a speedometer work on a boat?

 

[B-Dozer]

Re: speedometer help

That plastic line runs to a little hole in lower unit of outboard. and that somehow tells you the speed. The hole is very small and easily clogged, just try to blow through it. That worked for mine .

 

[Silvertip]

Re: speedometer help

The speedometer is driven by a pitot that is either a separate plastic unit screwed to the transom or as mentioned, it is built into the lower unit of the drive. As the boat moves through the water, water pressure compresses air in the tube and that pressure tries to unwind a Bourdon tube in the speedometer head which is linked to the needle. The more the tube unwinds the higher the needle goes. That is also why the speedometer doesn't begin to register until you reach 10 MPH or so. There just isn't enough pressure in the tube. Clean the pitot and check for a disconnected or pinched tube. The electrical connections on a speedometer are for the internal light only.

 

[bigrockk]

Re: speedometer help

Recently I had trouble with my Speedo and received some great advice here:

http://forums.iboats.com/showthread.php?t=565224&p=3882674#post3882674

Hope this helps

 

[carholme]

Re: speedometer help

If the engine you are referring to is the 1986 60 horse as seen in your previous posts, here is the parts listing:

http://www.crowleymarine.com/mercury-outboard/276.cfm

Under GEAR HOUSING (DRIVE SHAFT) you will see item 2 which screws down into the front of the LU just in front of the shift shaft. You can see the hose it is attached to and you will probably find this sticking out the front of your engine.

If you look on your engine just below where the number one is pointing to, you will see a small hole which is the water inlet for the speedo. Notorious for plugging up.

Gerry