troubleshooting spedometer merc 3 litre inline 4

[wcsparky05]

my spedometer has never worked since i bought the boat and i would like to know where to start to fix it. thx. by the way, its an '89 invader 16' merc alpha 1 if that helps?

 

[DukesFin]

Re: troubleshooting spedometer merc 3 litre inline 4

I could be COMPLETELY wrong, but a speedo has nothing to do with the motor.

Speedometers on boats usually use a paddle wheel on a transom mounted transducer or a little plastic "fin" that is mounted on the bottom of the transom.

Not sure where to start diagnosing the problem. If it were me, I'd just get a whole new "set up" for speedometer. I use my GPS to check my speed though.

 

[tommays]

Re: troubleshooting spedometer merc 3 litre inline 4

i am really not qualfied to help unless it is a thermostat.


Tommays

 

[8x56mn]

Re: troubleshooting spedometer merc 3 litre inline 4

my spedometer has never worked since i bought the boat and i would like to know where to start to fix it. thx. by the way, its an '89 invader 16' merc alpha 1 if that helps?

If it's the venture type, try looking to make sure some insect hasn't decided to lay eggs in the intake tube, if so remove the debris and blow compressed air into the intake and see if the Speedo moves at all. If the Speedo doesn't move remove the line from the Speedo and try blowing air backwards, this will tell you if you have a blockage somewhere in between. If the line is clear than you have a problem with the Speedo and you will most likely have to replace. This happen to me last summer

 

[Gotsteam]

Re: troubleshooting spedometer merc 3 litre inline 4

If it's the venture type, try looking to make sure some insect hasn't decided to lay eggs in the intake tube, if so remove the debris and blow compressed air into the intake and see if the Speedo moves at all. If the Speedo doesn't move remove the line from the Speedo and try blowing air backwards, this will tell you if you have a blockage somewhere in between. If the line is clear than you have a problem with the Speedo and you will most likely have to replace. This happen to me last summer[/quote]


I agree with him. Underneath the upperunit is an antisiphon plate, and there is a connector for the speedo for use when removing the drive. My plastic connector was broke, and had to be replaced. You might want to check to see if it is hooked up, and in good condition.

 

[Don S]

Re: troubleshooting spedometer merc 3 litre inline 4

I agree with him. Underneath the upperunit is an antisiphon plate, and there is a connector for the speedo for use when removing the drive. My plastic connector was broke, and had to be replaced. You might want to check to see if it is hooked up, and in good condition.

The 89 Alpha I drives didn't have that, it only came out in 91 on the Alpha I Gen II drives

The Invaders i've seen all have the pitot tube type speedometer from the factory. On the back of the boat is the pickup which will look similar to the one pictured.

They have a hose attached to the top of it that transfers the water pressure to the gauge and is calibrated to give you the speed from the water pressure.
Those pitots do get plugged up with marine growth. They can also get kicked up if you run over a log or something. Make sure it's sticking down into the water.

 

[bruceb58]

Re: troubleshooting spedometer merc 3 litre inline 4

Pull the tube off the speedometer end and try to blow through it to see if it is clogged.

 

[wcsparky05]

Re: troubleshooting spedometer merc 3 litre inline 4

thx. everybody. dons and others were right! the pitot tube was siliconed but not connected! thx again. got one for you about filling my cooling system... will post soon!

 

[FlyinGuy1017]

Re: troubleshooting spedometer merc 3 litre inline 4

Hey all,

Had a clogged pitot inlet in my '92 Sea Ray. Somehow a piece of wood was stuck in there. Ended up having to drill it out...

Here's the boneheaded part...How does one go about getting the broken drillbit out of the hole!?!

It's too far in to get anything on it. I tried blowing it out w/ compressor, not enough restriction to build up pressure. Magnet didn't work. Any suggestions out there?

Thanks.

 

[chiefalen]

Re: troubleshooting spedometer merc 3 litre inline 4

Why bring back a post from 2007 and not start your own thread.