How to Unclog Speedometer Tube?

[bankerjohnfl]

I recently bought a "new" boat with a 115hp Yamaha, and digital gauges. The gauges were both bad (LCD unreadable), so I purchased and installed new gauges. Problem is, the speedometer only displays a single bar ... no speed readings. I believe my problem is that the 1/16" hole in the leading edge of the lower unit is clogged up. My question is ... how do I unclog it?

Here's what I've tried so far:

Cleaned out the hole with a 1/16" drill bit.
Disconnected the "water tube" at the top of the lower unit and tried (a) blowing thru the tube, and (b) connected a syringe filled with water and tried forcing water down from the top.

Neither attempt was successful.

So am I going to have to drop the lower unit and replace the water tube ... or does someone have another suggestion?

[jb123]

easiest thing to do is to install a pitot tube as the yammie tubes get clogged much.

[bankerjohnfl]

If I installed a pitot tube on the transom, would I have to run completely new tubing to the speedometer ... or could I tap into the existing tubing where there's already a connector above the lower unit of the motor?

[jb123]

i prefer not to wrestle with clogged tubes so i use pitot tubes, others here would not and use the factory one on the motor, just way too inconsistent for me. you can splice into the tubing anywhere you like and its quite cheap at home depot, about 5 bucks a roll.

[bankerjohnfl]

Come on guys ... surely someone has an idea of how to unclog the line without removing the lower unit!!!

[CHRIS]

i just had the same problem on my 200yam. above the lower unit the tube should be sticking out with a connection . pull apart and blow through it or run water through it or shove a piece of music wire through it. also disconect from speed nometer and do the same while disconected at lower unit. takes about 15min.

[Bluebird]

I would run a new hose from the pitot to the speedo. I did not and now its clog again probably at the joint.

[brewski]

I ran a drill bit in the hole with a Makita battery operated drill, don't use electric, because water will come out when you get it open. Just make sure it is straight in and go slow.

[mark115]

My speedomoter never worked but after reading this thread I thought I'd try to fix it. I tried unclogging the port I disconnected it from the lower unit but it was clear through there.....What's the problem??? Well let me tell you. I connected the tube from the gauge to the engine using the connector that was on the motor and that connector did not pass through! It was a plug I guess. Very frustrating in a way. It works now though so I'm over it.

[plot4]

How about pulling the speeo tube apart where the connection is between the engine and speedo tube. When it comes from the factory there is a end on the connector that has to be cut off to open up the flow. If the previous owner didn't have a speedo then the tip probably was not cut off.

[Mako1623]

used a 1/6" drill bit to unclog mine using a hand drill it broke off level and cannot grab with anything including a magnet any ideas ?

[zenoahphobic]

used a 1/6" drill bit to unclog mine using a hand drill it broke off level and cannot grab with anything including a magnet any ideas ?

I remember reading this old post.
Breaking a drill bit in whatever situation is nasty because it would be harder than any material around it.
I think you may need to "destroy" the area and have it aluminium rewelded and a new tube fitted. If you did this you may backtrack to the blockage if it is nearby.
Create a new thread so your problem is uniquely addressed.

[pstephens46]

When folks suggest using the proper size drill bit to clean the opening.....I don’t think it was intended that the bit be attached to a drill.

[zenoahphobic]

When folks suggest using the proper size drill bit to clean the opening.....I don’t think it was intended that the bit be attached to a drill.

Oh it can be that, just don't activate the drill😀

[DennisG01]

used a 1/6" drill bit to unclog mine using a hand drill it broke off level and cannot grab with anything including a magnet any ideas ?

Do they even make a 1/6" bit? Seems like that would be too big. But, as others mentioned, the idea is to do it BY HAND.

I have no clue what engine you have, but...

-- Drill bits are magnetic.
-- Find the next connection point for the pitot further upstream, open the connection (cut and splice tube, if you want, or go all the way to the speedo) and blow compressed air into it.
-- Combination of the above two.
-- Cut the pitot hole slightly larger (cut off wheel or hacksaw) so you can grip the bit.