Spedo not working..

[Starcraft5834]

Mechanical Spedo not working, 1987 Alpha 1 drive... I did a little searching last year,, tried clearing the intake port,, used a week whacker line and ran it in as far as I could,, went in quite a ways.. seemed clear,, still did not work, what else should I look for? guage busted maybe? how do these things work?. I've got a GPS anyway.. would like to get original speedo working if possible.. thanks

 

[MH Hawker]

Re: Spedo not working..

if you have a vac / pressure tester you can put a bit of pressure in the tubing going to the speedo and see if it holds pressure and moves it.

 

[Starcraft5834]

Re: Spedo not working..

tubing is probably shot....I do not have one of those testers.....

 

[foodfisher]

Re: Spedo not working..

As speed increases, water is forced into the opening and up the hose causing pressure in the guage to register your approx. speed. Any clog, break, disconnect on the way will cause a malfunction.

 

[Starcraft5834]

Re: Spedo not working..

do I have to pull the drive apart to run a new hose line?

 

[UncleWillie]

Re: Spedo not working..

Sticking a wire in the pitot opening only gets you into a large cavity in the drive.

You will need to lay down under the drive to see any of this.
Trim the drive to Full UP.
On top of the front end of the Anti-Ventilation plate will be the Speedometer Hose Connection.
Twist the connector 1/4 turn and lift off.
Some connectors have a Button on the side that releases them.

The Speedometer just reads Pressure.
Pressuring this hose will make the speedometer indicate a speed.

For your Reference...
1.5 psi = 10 mph
2 psi = 12 mph <<< Typical pressure produced by a set of young health lungs.
6 psi = 20 mph
13 psi = 30 mph
23 psi = 40 mph
52 psi = 60 mph ... Notice that the scale is exponential; twice the speed gives 4 times the pressure.

 

[Starcraft5834]

Re: Spedo not working..

thanks Willie. will check that out as soon as the 3ft of snow melts around it :joyous:

 

[thumpar]

Re: Spedo not working..

On a 1987 it would be not be a gen 2 and would have a separate pitot pickup on the back so it is nothing to do with the drive. Without a pressure tester it will be hard to diagnose other than visually inspecting everything.

 

[AquaholicMike]

Re: Spedo not working..

Had a similar problem on my 96 Alpha outdrive, found the tube was out of the connector and the hole was clogged. Got the hole cleared and stuck the tube back on. Speedo worked for about 10 minutes until the tube popped back off. What is supposed to hold the tube in that plastic connector? Where can I find that connector part? Couldn't find it on this site or in a mercruiser parts catalogue.

 

[thumpar]

Re: Spedo not working..

Had a similar problem on my 96 Alpha outdrive, found the tube was out of the connector and the hole was clogged. Got the hole cleared and stuck the tube back on. Speedo worked for about 10 minutes until the tube popped back off. What is supposed to hold the tube in that plastic connector? Where can I find that connector part? Couldn't find it on this site or in a mercruiser parts catalogue.

You have a gen 2 if the year is correct. Totally different setup. You should open up your own thread.