Clearing the speedo tubes.....

[2kwik4u]

I've heard and read that the speedo's on boats are notorious for getting clogged with debris. The speedo on my boat was acting flakey on the test drive, and the seller commented that it just needed to be "blown out".

I did some research and read a few articles. Seems that some people think driving in reverse under full power (obviously away from anything else) will clear the pitot tube. They described it as driving in reverse creates suction instead of pressure on the tube. Any truth to this?

If theres no truth to the above statement then perhaps someone could direct me as to where to look to "blow out" the tubes, and get my speedo working.

I know that the speedo is nowhere near accurate, and I should get a hand held GPS to get a true speed. It's more the idea that I have a gauge in the cluster that isn't working. I'm just slightly OCD about everything working, and operating as it should.

[DaleM]

Don't "blow" anything out just yet.  Look on the front lower portion of your drive, below the cavitation plate, and you will find a small hole (1/8") or so on the leading edge.  That is the opening for the speedo tube.  As for cleaning it out.  The reverse method will work but in my experience only if the clog just happened or it isn't too tight.  After you come off plane and the boat has just a little bit of forward motion move the shifter into reverse and gun it just enough to stop that forward motion.  Only for a second.  In other words you don't want the boat to go backwards at WOT.  It will be e pretty good "jerk".  Try it 2-3 times.  If that doesn't do it sometimes you can take a small stiff wire (paperclip) insert it into that hole and get the crud out with it.  If its really tough lift the drive to the trailer position and locate the speedo tube where it comes up out of the lower drive.  Disconnect it and "blow" out only the section going down to the opening.  Blowing anything towards the speedo without disconnecting the tube from the back of it will destroy it in a heartbeat.  Goodluck and welcome to the site.

[Sunny side up]

My Rinker dealer advises this clogging can be common and advises to get a drill bit just smaller than the speedo hole and use it to loosen out the debris.

[Babyboomer]

My Rinker dealer advises this clogging can be common and advises to get a drill bit just smaller than the speedo hole and use it to loosen out the debris.

Super glue a wire nut on the bit this gives you a grip, when finished I keep mine in an oiley rag in a zip lock bag.

[2kwik4u]

Thanks fellas....I tried the go fast in reverse thing yesterday. Didn't help at all ....Guess I'm off to find the hole, and a drill bit to stick in there and clean it out.

[rdlegacy]

Mike

Some time ago, I had a similar problem.  While boating on the Allegheny river there was a lot of floatsom due to a recent rain.  I was going at idle speed when I hit a submerged log.  That lodged a chunk of wood in the speedo inlet.  It took me a few days to realize I had a problem.  I used a small drill bit, by hand, to dislodge the debree, it worked!

So hopfully, it will work for you.

Bob

[2kwik4u]

I'll give that a try.

This tube is supposed to be on the bottom of the outdrive? Anyone have a picture?

[2kwik4u]

OK guru's here's some pictures. Kinda crappy camera-phone pics, but pics none-the-less.

I went outside and looked at the back of the lower unit (you can see in one pic I have a finger pointed at the back), and found a tube that is disconnected. It looks as though there is a small fitting that the tube is supposed to be connected to, but has popped off. Can you guys review these pics, and tell me if this is what I'm looking for to get my speedo working? It was driving me crazy sunday to not have it working. Not that it's accurate, just that I want all my guages to work properly.

Anyway on to the pics. Please let me know what you guys think. (clicking will get you much larger images)

[Dream 'Inn]

Mike, yes, that looks like the tube!  Snap it back on and you should be good to go.  Also take a peek just a bit lower than that on the forward facing part for that little hole and make sure it is clear.

If you want, you can also blow into that tube and if I remember right it will move your speedo a little (you need to 2 people to see it though).

[2kwik4u]

Thanks for the reply. I'll have a buddy watch the speedo, and check that tonight, as well as insure that hole just below it is clear of debris. Anything else I should check before I head out in regards to the speedo?

Going to put a towel on the ground tonight though. The gravel last night wasn't real nice to my slightly sunburnt back :D

[2kwik4u]

If the weather holds for a few hours, I'm gonna try it out tonight.....everyone cross your fingers

[2kwik4u]

It worked!!!

Nothing more than plugging that line back in. I checked all the holes I could find on the outdrive, and they were all clear of debris for as far as a small drill bit would fit into them.

I do think it's off though. It only reads about 18mph once on plane, with a top speed of ~38mph at 4600rpm with WOT. I've got a buddy with a handheld GPS that I'll use to verify it here soon.

[DaleM]

Speed might be a little low.  One other thing you might check is to be sure that the tubing from the back of the speedo to that fitting is clear.  Being disconnected you may have gotten some water or even an insect (spider with a web) up in it.  That might reduce the amount of pressure that is actually getting to the speedo producing a lower reading.

[2kwik4u]

I crawled up under the dash last night while on the water (GF was making sandwiches :(

[Dream 'Inn]

Well, that's good to hear it worked!  Just be a bit careful behind the dash, some of the power is "alive", especially with the key turned on.  It's DC power, so it wouldn't harm you, but you could harm the gauges.  While you're back there, you can make sure connections seem tight too .  Especially grounds.