Logo
FULL SITE MENU

speedometer

J

jkyzer

Member
hi all,
I have a question about speedometers. Last time out to the lake, my speedo didn't work. I have disconneted the line at both ends and is clear.
Now the question: How much pressure does it take for the needle to move, and, does it work on air or water press? I can't blow on this one enough to make the needle move!
Thanks,
J
 
I don't have the tech specs on how much pressure = "x" mph, but yes, works on water pressure.

So since your needle will move if you blow in the tube and the tube is clear then you probably have a blocked pitot (pick-up).
 
Actually water does not gain access directly to the speedometer. The water creates a air pressure condition that causes the needle to move. Unlikely you'll be able to physically blow in the line hard enough to make the needle move..... it would normally take a fair amount of compressed air to have that happen.

As "galamb" states, the most likely cause is a clogged pickup pitot.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store
 
Hey,
Justchecked the pitot with the tube disconnected at speedo, and is clear
all the way,(that part is easy to blow through). But when I attach a short piece
of tube to the speedo direct, I can't blow enough pressure to move needle. Probably
a locked up speedo.
Thanks,
J
 
Hey,
Well I got speedo to work. Maybe stuck diaphram inside the speedo. Took it out of
boat and got the ol' compressor out and short piece of tubing, and tried my luck.
Useing a very touchy regulator, I use for airbrushing, I slowly added pressure.
At about 45/50 psi, I heard a slight "pop" and needle jumped to about 60mph.
Then it started operating at about 12/15psi it showed 20mph. Got to playing with
it, and it seems to be working fine, now.
Joe, and J W from reading the posts on this site, you guys always amaze me with you knowledge of marine stuff.
I have been in aircraft maint. since 1966, so if you readers have a question about
aviation, feel free to e-m me. ([email protected])
Thanks for the help,
J
 
Back
Top