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View Full Version : Dang airguide speedometer problems again


jss101
07-01-2007, 09:32 AM
My left speedo is busted on my 205V. I've been reading what I can find on this - people say "you have to blow it out", but I can't find a good description of what that really means (ah, there's lots of joke potential here... I'm trying to resist!)

Where do I disconnect the tubes and what do I use to blow? By mouth? An air compressor? The tubes seem to connect to the slanted black sensors on the transom and then routed up the boat to a panel mounted on the bulkhead in front of the driver's knees.

Any help!? Taking it to the dealer is a big deal and probably won't happen until I winterize..

Thanks!!:confused:

TMCNo1
07-01-2007, 11:12 AM
Take the line loose from the pickup on the transom and blow into it while having someone watch the gauge. Then blow into the pickup and see if air comes out of the stem where the line goes on. If the pickup is stopped up, clean from both ends with a safety pin, paper clip, straight pin or a small drill bit turned slowly by hand and/or blow out with a air compressor. It won't take much air to clear.

Jim@BAWS
07-01-2007, 01:09 PM
DO NOT BLOW COMPRESSED AIR TOWARDS THE SPEEDO HEAD
YOU WILL BLOW THE DIAPHRAM !!!

Only out of the speedo p/u

jss101
07-02-2007, 10:58 AM
Thanks very much. I cleaned out the pickup with a safety pin and now the gage registers. It's weird, however. It's "slow". It gets up to the right speed (matching the other one) but it takes a while. Likewise, when you stop, it takes a while to go back down to zero. Very strange. Any ideas on that?

jss101
07-02-2007, 11:00 AM
OKAY!! :-)Thanks.

east tx skier
07-02-2007, 11:01 AM
If the pickups were clogged, they will likely clog again. The replacements are about $13 each and have wider openings. Haven't had to take a safety pin to my new one since I bought it. Works great!

jss101
07-02-2007, 02:31 PM
What are those pickups officially called? Do you know a part number? I'd like to order them on line from somewhere...

mark g
07-02-2007, 02:55 PM
pick ups are called "pitot" ski dim has them part no 1804, not air guide but replacement parts
pronounced pito

Jesus_Freak
07-02-2007, 02:58 PM
pick ups are called "pitot" ski dim has them part no 1804, not air guide but replacement parts
pronounced pito

actually pronounced "pee-toe", as in pitot tube, as in a device which measures stagnation pressure and, using simple algebra, determines the approach velocity along a fluid streamline exactly perpendicular to its tip.

TMCNo1
07-02-2007, 03:07 PM
actually pronounced "pee-toe", as in pitot tube, as in a device which measures stagnation pressure and, using simple algebra, determines the approach velocity along a fluid streamline exactly perpendicular to its tip.

WOW, and the whole time, I thought it was pressure related!:woohoo: :popcorn: :uglyhamme

mark g
07-02-2007, 03:09 PM
:rolleyes: mine just measure the speed for now if i wanted algebra equations i'd have gone to work

east tx skier
07-02-2007, 03:40 PM
On those pitot pickups from ski dim, you'll need to drill two small holes right and left of center of the center of the attachment plate to get them to line up with the holes on your boat. Don't worry about the one at the top. Fill the old holes with 3M marine sealant and reset the screws. Attach the rubber tubing and you're done.

pilot02
07-02-2007, 04:34 PM
Definitely get the venturi pickups from skidim. They seldom clog and if they do, you can typically just hit reverse for a second and they'll clear.

jss101
07-02-2007, 09:09 PM
I be learnin' somethin' evry day!
Thanks everyone for your help.

No one commented on the "slow to respond" note. Any thoughts about that?

WTRSK1R
07-02-2007, 09:13 PM
I would bet that the slow to respond is just a partial blockage that will likely be fixed with a new pickup. If there is a partial blockage the total pressure will still be the same, it just takes longer to register, and then takes longer for the pressure to bleed back off. Just a guess though.

Steve

jss101
07-02-2007, 09:13 PM
On those pitot pickups from ski dim, you'll need to drill two small holes right and left of center of the center of the attachment plate to get them to line up with the holes on your boat. Don't worry about the one at the top. Fill the old holes with 3M marine sealant and reset the screws. Attach the rubber tubing and you're done.
Yikes! Drill into the transom! Yikes! Sorry. Ok. I read it here so it must be okay, right? :-)

Sorry. Making extra holes in my boat doesn't let me sleep well at night!

WTRSK1R
07-02-2007, 09:23 PM
I am almost certain he meant that you need to drill holes in the new Pitot assembly to match the existing holes in the boat. NOT the BOAT.

jss101
07-02-2007, 09:28 PM
Oh!
Much better!
:D

yankee
07-03-2007, 04:20 PM
That definition is actually what's used on the static port of an aircraft. A boat speedometer is operated on pressure that's why the pick-up hole in the pitot faces forward instead of side ways. On a plane it's a small opening usually near the pilot.

east tx skier
07-03-2007, 04:43 PM
Yikes! Drill into the transom! Yikes! Sorry. Ok. I read it here so it must be okay, right? :-)

Sorry. Making extra holes in my boat doesn't let me sleep well at night!

No, drill the pitot assembly so that the holes match the wholes on your transom. Fill the holes on the transom with the marine sealant to seal around the screw holes when you reset the screws.

I am almost certain he meant that you need to drill holes in the new Pitot assembly to match the existing holes in the boat. NOT the BOAT.


Gesactly.

east tx skier
07-03-2007, 04:45 PM
That definition is actually what's used on the static port of an aircraft. A boat speedometer is operated on pressure that's why the pick-up hole in the pitot faces forward instead of side ways. On a plane it's a small opening usually near the pilot.

It doesn't face forward on a plane? It's been a while since I've checked one for dirt dobber nests, but I could've sworn that it faced forward.

Jesus_Freak
07-03-2007, 04:55 PM
It doesn't face forward on a plane? It's been a while since I've checked one for dirt dobber nests, but I could've sworn that it faced forward.

A pitot tube would have to face a direction into, and perpendicular to, the relative motion in order to "feel" a correct stagnation pressure. Facing any other direction would result in reading a speed lower than reality due to secondary pressure losses.

pilot02
07-03-2007, 05:29 PM
I would bet that the slow to respond is just a partial blockage that will likely be fixed with a new pickup. If there is a partial blockage the total pressure will still be the same, it just takes longer to register, and then takes longer for the pressure to bleed back off. Just a guess though.

Steve

I'd be willing to bet that the blockage is in the "balance tubes" (brass cylinders mounted inside the boat near the transom. They seem to be prone to causing this sort of thing.

G-man
07-03-2007, 05:36 PM
I'd be willing to bet that the blockage is in the "balance tubes" (brass cylinders mounted inside the boat near the transom. They seem to be prone to causing this sort of thing.


I agree try here first if this doesn't work disconnect the tube from the back of the gauge and blow towards the back of the boat

pilot02
07-03-2007, 05:37 PM
That definition is actually what's used on the static port of an aircraft. A boat speedometer is operated on pressure that's why the pick-up hole in the pitot faces forward instead of side ways. On a plane it's a small opening usually near the pilot.


On a plane, you actually have 2 ports. A Pitot for Ram Air and a static port located on the side of the fuselage to compensate for the pressure changes that results inside the aircraft in flight. You also have to understand that airspeed is referred to in three ways when flying.
Indicated - what the ASI actually shows.
Calibrated - corrected for installation and position error (static port effectiveness changes based on flight attitude)
True - which is calculated using the calibrated airspeed and current density altitude....

jss101
07-04-2007, 06:20 PM
I agree try here first if this doesn't work disconnect the tube from the back of the gauge and blow towards the back of the boat

Thanks everyone for your help.
Two things here: 1. the tubes don't seem to go to the back of the gauges on the dash. They seem to go to a panel mounted on the bulkhead in front of the driver's knees. It's hard to tell, since it's nearly impossible to get to the back of the gauges. It looks like you'd have to take the whole dash shroud off to get to them. 2. people have mentioned these brass thingys. It's really hard to get back there; I've opened the rear hatch pretty far and crawled in there, but due to the manifolds it's kind hard to get my head back in there to look. Maybe I'm confused, but if I have to get to these brass tubes I have no idea how to do it!

east tx skier
07-05-2007, 12:06 PM
On a plane, you actually have 2 ports. A Pitot for Ram Air and a static port located on the side of the fuselage to compensate for the pressure changes that results inside the aircraft in flight. You also have to understand that airspeed is referred to in three ways when flying.
Indicated - what the ASI actually shows.
Calibrated - corrected for installation and position error (static port effectiveness changes based on flight attitude)
True - which is calculated using the calibrated airspeed and current density altitude....

Ah, yes. It's coming back to me now. Forgot about the static port.

Haven't flown myself in 15 years.

jss101
07-10-2007, 10:33 AM
Does anyone know - :confused:

Does the airguide speedometer system on my 205V have the brass balance tubes? Or is it possible that it's a different system from the ones people keep talking about here?

I'm trying to decide if it's worth it to start disassembling stuff to get down there. I hear that they are on the inside of the transom where the black plastic tubes come into the boat. It's really hard to see down there with the way the manifolds are positioned. I can't get in there very easily. I'm thinking of taking apart some of the panels to see if I can get in there to see. However, is it worth it!!?

Any info would be appreciated!!!
Thanks.

P.S. If you've been reading the whole sad story in this thread - I do have both speedo's working again, but the left one is slower to respond both on acceleration and deceleration. Very strange!

Thanks again.

alletric
07-11-2007, 09:28 PM
When installing the new style pitot do you think that it would be a dumb idea to install the third screw by predrilling and then using the correct SS screw? I just didn't know if the increased stability of the mount would out weigh drilling another hole in the boat. Just got them in and was wondering before I change them.

ghind
07-02-2009, 10:14 AM
Information about airguides including repairs and why they break (how to avoid busting yours etc) can be found at www.airguide.com.au

sethro
07-02-2009, 05:02 PM
When installing the new style pitot do you think that it would be a dumb idea to install the third screw by predrilling and then using the correct SS screw? I just didn't know if the increased stability of the mount would out weigh drilling another hole in the boat. Just got them in and was wondering before I change them.

That would be overkill without a doubt...using some 3M 4200 adhesive sealant would increase stability if you are concerned about that. And new holes don't have to be drilled in the pitot, the holes on the pitot can just be elongated a tad with a drill bit for them to line up with the holes in the transom.