When I start the engine, my speedometer reads high (88mph) while boat is still in neutral. The reading slowly moves lower, but never goes below 30 mph no matter how fast/slow the boat moves. Has anyone had this problem?
need to fix speedometer on my 225
- Thread starter ewickwire
- Start date
Extremely common and lot's of threads on this on just about every single boat forum out there.
99% of the time, drilling out the pitot hole in the lower unit (small hole in leading edge, just above gear housing) solves the problem. Use a small drill bit BY HAND.
99% of the time, drilling out the pitot hole in the lower unit (small hole in leading edge, just above gear housing) solves the problem. Use a small drill bit BY HAND.
I am not sure this is a plugged pilot hole issue. Usually when the pilot hole is plugged, the speed reads low and may slowly increase over time as water pressure manages to get past the blockage. In that case, the unit will often also read not react quickly as you slow down.
Since this problem starts out as a high reading (although 88 sounds like a self test mode display reading) I would think that something else is at fault.
I agree that cleaning the pilot hole is the first step but I don't think it will fix the problem
Since this problem starts out as a high reading (although 88 sounds like a self test mode display reading) I would think that something else is at fault.
I agree that cleaning the pilot hole is the first step but I don't think it will fix the problem
It may not, you're right - could very well be something else. And, I agree the 88 is kinda strange. But I have had some speedos do exactly what is described - start high, and then slowly come down. Sort of like a one-way valve thing happening in the pitot hole. It let's water in to pressurize the tube, but the water doesn't come back out as easily. Most recently was when my brother "helped" me touch up the bottom paint... :roll: Can't fault a guy for trying, though! 
I understand but based on the original description the spedo reads high as soon as the motor is started and not necessarily in gear and moving. The way to tell would be to disconnect the water tube from the pressure sensor in the bottom cowling. That can be a pain to get to on some motors.DennisG01 said:It may not, you're right - could very well be something else. And, I agree the 88 is kinda strange. But I have had some speedos do exactly what is described - start high, and then slowly come down. Sort of like a one-way valve thing happening in the pitot hole. It let's water in to pressurize the tube, but the water doesn't come back out as easily. Most recently was when my brother "helped" me touch up the bottom paint... :roll: Can't fault a guy for trying, though!
My motor spedo gets fouled up all the time and is not all that accurate when it does work. I don't even look at it. I rely on the plotter for speed info.
Parthery
GreatGrady Captain
This sounds more to me like the gauge might be shot. (Also a not uncommon problem.)
If clearing the pitot hole doesn't resolve it, I'd start watching eBay or check with your local dealer. I know my dealer has a box of old gauges lying around from repowers....often times you can pick one up cheap.
If clearing the pitot hole doesn't resolve it, I'd start watching eBay or check with your local dealer. I know my dealer has a box of old gauges lying around from repowers....often times you can pick one up cheap.
seasick said:
Hmmm. You know, to further elaborate on your point... If the speedo starts high EVERY time that the engine is started, yet the speedo was showing a lower number when it was turned off, then that likely negates the clogged speedo theory.
In that case I would look at the pressure sensor and/or gauge as mentioned by Parthery. I would "imagine" that there's a way to test the pressure gauge - assuming it converts pressure to resistance/ohms. But I'm not positive on that and don't have my manual with me right now. If there was a way to test the pressure sensor, then it would be easy enough figure out where the issue is.
WE probably should have asked what gauge he has. That 88 reading sure sounds like the self test display in which case that would be normal for a couple of seconds. It would then drop down to zero normally but if the tube is plugged and under some pressure, it would read something above zero.