Speedomoter isn't working

[korygrandy]

Merc 3.0l alpha 1, not sure the serial number. My speedometer is not functioning. Does anyone know where the sensor is located? It appears something is missing next to the outdrive and I'm thinking the part that senses the speed to the speedometer is gone.

 

[Blk-n-Blu]

Re: Speedomoter isn't working

Not sure if the Alpha 1 has an internal speedo tube but sounds as though you may have lost your Pitot tube pick-up that usually mounts next to the drive on the hull if so there should be a plastic tube remaining that runs through the transom and right to the speeometer gauge. You may want to download the manual for your drive from the "Adults Only" sticky thread at the top of the forum page where you originally posted this.

 

[ezmobee]

Re: Speedomoter isn't working

I believe on your alpha the speedo works via a pressure tube that connects to an inlet hole in your outdrive. The pressure of the water trying to push into that hole is what is measured by the gauge. Someone more knowledgable than me will hopefully come along and tell you exactly where that hole is. They can easily get blocked due to debris.

 

[180shabah]

Re: Speedomoter isn't working

Speedo is really just a pressure gauge. There is a tube running from the gauge to the pitot. It could be either a small plastic "fin" mounted on the transom, and hanging lower than the hull bottom.

OR

If you have a GenII drive, the pitot is built in. Check for debris in the tiny hole on the leading edge of the drive and make sure the connector between the upper and lower unit had not come undone.

 

[scoutabout]

Re: Speedomoter isn't working

...
OR

If you have a GenII drive, the pitot is built in. Check for debris in the tiny hole on the leading edge of the drive and make sure the connector between the upper and lower unit had not come undone.

^^^ What 180 said. I had a 3.0 alpha drive in our previous SeaRay and hit a partially submerged log one day. Speedo went dead immediately and I discovered the leading edge opening in the outdrive was plugged with a very small slice of soggy wood.

Picked it out with a pin and was good to go again. Also, as mentioned, make sure the pressure tube (black, flexible plastic, about the diameter of a small straw) is connected.

Water intake on my alpha drive was in and around the area shown by the red box. It's quite small and it doesn't take much crud to block it up. The pressure line for the speedo on mine was on the opposite side of the drive pictured but could be seen up near the silver pressure lines for the trim pistons.

 

[mike343]

Re: Speedomoter isn't working

I would have to believe that the number of boats with transom mounted flip-up pitots are several times that of engine mounted units. Yet the boating sites are full of problems with wood jams in the latter. If I had a new boat with a pick-up on the lower unit I'd put in a transom mounted one immediately after reading about all the problems.

 

[korygrandy]

Re: Speedomoter isn't working

You guys were correct. There were the remains of wood particles in the outdrive that I was able to pick out with a safety pin. The more wood I picked out the wetter the wood got and then came water bubbles with a slight dribble. I used an eyeglass screwdriver to clean out the rest.

 

[Friscoboater]

Re: Speedomoter isn't working

I have never seen the speedo in the drive. Mine is just a little tube.