Broken Speedometer

[acevedor2]

Hey guys, the speedo on my new (to me) 2008 Bayliner 185 flight is not working. All other gauges work. From my reading and searching on this forum and the net it appears I need to check to see if the pickup at the stern drive is clogged. That said - where is the pickup? I cannot seem to find it. Any picture would be wonderful.

I don't know if this is a related issue, but when I looked under the dash, I see this errant hose. It's too short to go to the speedo and all other gauges work, so I am not sure what it is for. Any thoughts?

 

[generator12]

Re: Broken Speedometer

The speedometer works by measuring the pressure generated by the water against a small pickup unit by the forward motion of the boat. The pickup is a small (4 inches or so) piece - usually plastic or some such composite - extending down off the back of the boat, the tip of it riding lower than the bottom of the boat. There will be a small (1/4 inch or so) tube connected to this pickup.

The water pressure against the forward edge of this sensor increases as the speed of the boat does, and that pressure is transmitted to the speedometer up front through the tube, which is connected to it and to the sensor (pickup). The speedometer is essentially a pressure gauge with its face marked with MPH rather than PSI.

If the speedo isn't working, the problem is usually a damaged sensor (about a seven or eight dollar item at a marine shop) or a cracked or leaking tube. It can also be due to a plugged sensor. (dirt, algae, etc.)

 

[Don S]

Re: Broken Speedometer

Look in the leading edge of the drives lower unit. There is a small hole there that can get plugged up with debris in the water. Clean it out with a wire and your speedometer will probably work. Unless the hose isn't hooked up to the lower unit.

 

[acevedor2]

Re: Broken Speedometer

Thanks, that is exactly the problem - the hose wasn't hooked up to the lower unit. Had it serviced right after I bought it. Oil, lube, etc. They basically disassembled the outdrive and went through it just to make sure. Since I had never used the boat, I assumed the speedo was broken when I bought it - nope - appears the service guys disconnected the tube. I reconnected and I would guess all will be well. Thanks for the help! What a great forum!