How do you clean out a speedometer pitot?

daveinstl

Cadet
Joined
May 25, 2008
Messages
7
The speedometer on my Optimax is stuck on 0 MPH. I tried cleaning out the pitot on my lower unit with a drill bit but that didn't seem to help. Has anyone else been successful in fixing this? On past boats I have just given up and put a pitot on the outside of the boat, but this one would be harder to do because it has a notched transom so running a tube might be difficult. Thanks.
 

jimg984

Chief Petty Officer
Joined
Jul 16, 2007
Messages
403
Re: How do you clean out a speedometer pitot?

take loose at speedometer and blow compressed air back thru it
 

cell

Petty Officer 1st Class
Joined
Apr 16, 2009
Messages
208
Re: How do you clean out a speedometer pitot?

My speedo didn't work until I cut a kink out of the tube I found.
 

sportsmanphil

Petty Officer 1st Class
Joined
Mar 8, 2009
Messages
257
Re: How do you clean out a speedometer pitot?

I have a butt connector on my speedo tube near the OB. I disconnected that and blew air toward the speedo and it worked. I tried to blow out the blockage between that butt connector toward the OB and its clogged. I poked drill bits into the pitot and felt nothing.

I cant get what ever is in the foot of the OB unclogged.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: How do you clean out a speedometer pitot?

Moss, algae, marine growth in general, will plug up the tube in the lower unit.

Careful with the wire attempting to poke it out often will push and compress the vegetation into a hard solid plug.

I've found the cheap Wally World carb cleaner to work well to kill the vegetation and sterilize the tube, a shot of compressed air blown back thru the tube from the butt connector usually clears the tube.

Add this to your list of seasonal maintenance.
 

Dave-Oxford

Recruit
Joined
Oct 4, 2009
Messages
2
Re: How do you clean out a speedometer pitot?

After a while I was finally able to clear my clogged sterndrive speedometer pickup hole today (after hitting a large stick on the water) with some of the suggestions provided here and other sources. I ended up using a 1/8" and smaller drill bit and spun it by hand at first to pull the debris out of the hole. After a time with no luck I gripped the bit with a pair of vise grips to help grap the debris inside the hole (mostly wood) and continued to slowly turn and pull out the debris especially since I had no idea how deep I would need to go and also didn't wan't to puncture the gear housing. Eventually I broke thru the clog and water poured out of the hole. I blew out the hole from the top tube connection with water and air at the end. At the end I measured the depth of the cleared hole at 1-3/4" so that next time I can use more twisting force until I get near the final depth. Note: I have a 2005 Alpha 1, Gen II drive so other types will likely have varying depths. Thanks for the help and I hope I can also help someone else with this issue.
 

daveinstl

Cadet
Joined
May 25, 2008
Messages
7
Re: How do you clean out a speedometer pitot?

On every outboard and stern drive that I have ever owned, I finally give up trying to keep the lower unit pickup clear and end up putting a cheap plastic pickup on the lower transom. Works great and never clogs, but does get kicked up once in a while. People like me who do their running on the river have more trouble with this.
 
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