Speedometer Questions

OllieC

OllieC

Well-Known Member
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Mar 11, 2013
6,902
N.W. ‘Sconnie
Boat Info
Sara Belle
2005 Weekender 215
Engines
Mercruiser 5.0 mpi, Bravo III
Happy New Year!

My speedometer gauge hasn't been working for a few years. It is an analog gauge. I have cleaned out the pitot tube so I don't think that is the problem. I know I can use the chart plotter, however I am planning on replacing all the gauges because they are fogged up, and I would like them working properly.

Last Spring I installed an NMEA Smartcraft backbone which attached directly to the Garmin unit. Once installed (correctly), the Garmin automatically detected the feed coming from Smartcraft to the appropriate digital gauges. The one gauge it does not detect is the speedometer. If the pitot tube was clogged, one would think that the speedometer would still register digitally on the Garmin but with 0 mph while underway?? This leads me to believe that it is not a pitot tube issue, but an electrical/digital/component issue instead.

Is there a fuse, or an electronic sensor that could have possibly failed?

Thanks,
Ollie
 
The 215, unlike the 225, came with a standard gauge package, not a Smartcraft gauge package... although your engine is Smartcraft "ready". As such, from the pitot hole in the drive, there is simply a long tube to the back of your speedometer. Somewhere, there is a clog. First disconnect the tube at the drive - just above the anti-ventilation plate - look into that cavity, you'll see the quick disconnect. Blow air into the drive side of the connection and it should easily come out the pitot hole. Blow air into the boat side of that connection, and your speedo needle should move. One of those pathways is clogged. OR... the tube is split somewhere (or popped off at the gauge), allowing water to leak out (and thereby not building pressure to spin the needle).
 
I think if my speedometer quit I would look at replacing it with a GPS speedometer. You should be able to find one that matches your existing (or new guages).
 
Lazy Daze said:
The 215, unlike the 225, came with a standard gauge package, not a Smartcraft gauge package... although your engine is Smartcraft "ready". As such, from the pitot hole in the drive, there is simply a long tube to the back of your speedometer. Somewhere, there is a clog. First disconnect the tube at the drive - just above the anti-ventilation plate - look into that cavity, you'll see the quick disconnect. Blow air into the drive side of the connection and it should easily come out the pitot hole. Blow air into the boat side of that connection, and your speedo needle should move. One of those pathways is clogged. OR... the tube is split somewhere (or popped off at the gauge), allowing water to leak out (and thereby not building pressure to spin the needle).
Click to expand...
Wouldn't the gauge still register in Smartcraft when I start the motor? I'm not even seeing a gauge.
 
OllieC said:
Wouldn't the gauge still register in Smartcraft when I start the motor?
Click to expand...
The speedo gauge is dirt simple. Take a look at how I described it above: Hole in drive... long tube... speedo. That's it. No electronic nothing.
 
Okay - Thanks Dennis. I have taken off the tubing by the cavitation plate and saw there wasn't a leak, so it must be up the line. Maybe I have it pinched by the helm where I've cable tied and cleaned up things.

I assume that the speedo information isn't attached to "Smartcraft" , and is completely analog. I do see the tube to the gauge. So, even if I get it working, it still will not register on the Garmin......that's where my mix up is.

Ollie
 
"I have taken off the tubing by the cavitation plate and saw there wasn't a leak, so it must be up the line" --- I'm not totally understanding what you are saying. Can you blow cleanly (no obstruction) between the pitot and the connector at the anti-ventilation plate?

You aren't getting water in the boat and can't figure out why, are you? The tube may have slipped off the back of the pitot. But, check for no obstructions as mentioned above - that will narrow things down real fast.

FYI... "anti-ventilation" plate, not "cavitation". Cav is a totally different thing than vent. :)
 
OllieC said:
I assume that the speedo information isn't attached to "Smartcraft" , and is completely analog. I do see the tube to the gauge. So, even if I get it working, it still will not register on the Garmin......that's where my mix up is.

Ollie
Click to expand...
Yeah, you're thinking too much on this one! :) Think about it this way... if the speed information was currently electronic... how would it work with your analog gauge? To get speed information in a Smartcraft system, you would have to add the pressure sensor. I've never added it, so there may be more to it... but youd have to do AT LEAST that.
 
Lazy Daze said:
"I have taken off the tubing by the cavitation plate and saw there wasn't a leak, so it must be up the line" --- I'm not totally understanding what you are saying. Can you blow cleanly (no obstruction) between the pitot and the connector at the anti-ventilation plate?

You aren't getting water in the boat and can't figure out why, are you? The tube may have slipped off the back of the pitot. But, check for no obstructions as mentioned above - that will narrow things down real fast.

FYI... "anti-ventilation" plate, not "cavitation". Cav is a totally different thing than vent. :)
Click to expand...
My apologies. I'm at work and was on a conference call while typing my response (the conference call wasn't that important). I meant to say 'it wasn't clogged' from the disconnect down to the pitot or hole in the Bravo 3. Yes, the disconnect above the "anti"-cavitation plate:D
 
Lazy Daze said:
Yeah, you're thinking too much on this one! :) Think about it this way... if the speed information was currently electronic... how would it work with your analog gauge? To get speed information in a Smartcraft system, you would have to add the pressure sensor. I've never added it, so there may be more to it... but youd have to do AT LEAST that.
Click to expand...
Makes sense to me now.
 
OllieC said:
"anti"-cavitation plate:D
Click to expand...
Wise guy, huh? :)

It's pretty rare for a clog to go all the way into the boat-side tube. The more likely scenario is that the tube popped off the gauge, has split/broken somewhere or, as you mentioned, got kinked. But, all of those scenarios as pretty easy fixes.
 
My 2011 260 DA w/B3 lost a speedo signal after some maintenance was performed on the engine. It turned out to be a wire that was disconnected somewhere which they found in about 10 minutes of looking.

Don't know if you have the same system in your boat.
 
Well, I used a small drill bit and a small Phillips OD screw in the pitot hole and freed the debris lodged in it. It took forever. There was a lot impacted and didn't realize how deep the hole goes before heading up towards the tube. That originally led me to believe there was something else going on.

I just purchased another yellow connector above the anti-ventilation plate. I'll attach a small hose to it and use it as a dedicated blow-out connection for when the next time this happens.

Thanks for the help
 
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