Dead Speedos

Ive got a 1991 MC tristar and both speedos dont work. I checked the connection at the rear "wings" and they are on solidly. Where else could I look to see what the prob is.

I get no movement whatsoever on the speedos at any speeds.

Thanks,

I am not sure if you have the tubes hanging of the back or if you have a paddle like the perfect pass. If you have the tubes hanging off the back, you should unscrew the tube from the back of the plastic piece that hangs into the water and use compressed air to blow out anything that might be in there. You would put the compressed air on the side that the tube came off in order to blow the stuff back out the way it came in. Sometimes you can use a paperclip or a needle, but compressed air works best. Even though it appears as though there is nothing in there, you would be amazed what you find. I have the same problem on a regular basis on the river.

getting any water at the dash? If so, the pressure tubes have popped off the back of your speedos. happens occasionally over time.

Sorry in advance for the thread hijack....but I have a 2001 MC 209 and neither of my speedos work either. Sometimes one would work and sometimes the other (not relevant, I know). But when I blow air through the pitot at the back, they both work, when I am in the water, I get nothing. Any thoughts? I have tried messing around with the electronic adjustments as well....nothing has helped.

A paper clip or a small drill bit will clear the pick up holes most of the time.

There are three components to pitot tube speedos in addition to the hoses (these do not include late model electronic units). From the back there are the pickups that develop water pressure, then inside the transom there are balance tubes (look like 3/4" x 1' brass tubes) they convert water pressure to air pressure, then the speedo's themselves.

It's pretty to easy diagnose the speedo's with a bicycle pump. I always start at the back pulling the tube off the pickup and pump air directly into the tube (may or may not require a fitting depending on your bike pump). If the speedo's register then you just need to clean out your pickup (the most common problem). Next, hook the pump directly to the speedo with a short hose and see if it's stuck, they almost always move indicating the problem is elsewhere.

The next most likely component is the balance tube, it might be stuck. A little more pressure from the pickup side might break the piston free. If not pull the hose off the speedo and pump there pushing the piston the opposite direction in the balance tube, then reconnect the speedo and try pumping from the back again. Still not moving? Locate and pull the balance tube and squirt a little wd-40 in the pickup side (not the speedo side). Keep track of thier direction, re-install them the same way. If you cannot get the balance tube piston moving replace it.

(Message edited by mikeski on June 26, 2006)

Mikeski, Thanks a ton, I will hopefully give this a shot today. This is a great how to. Much appreciated.
JB

I did the compressed air bit today and shot out a bunch of crap, even a pebble...
the guauges responded to air pressure so I think they should work again.

Thanks again guys you were a great help!