View Full Version : Speedo question...

07-14-2007, 08:16 AM
Put the boat in yesterday, ('98 mobius) has the "airguide speedos" one of the speedometers started filling with water inside the dial and leaking out the bottom... I checked feed tube under dash etc. all was secure, havent pulled the unit yet, anybody ever have this are know if they are repairable or just need to order replacement? thanks bob!

p.s.yesterday my boy Josh (15) fairly solidly added the 360 and the tantrum (landed 4 for 6) to his arsenal! was fun watching the big smile of victory... looked so fun that it made me give getting up a try, I'm a 6'4" 270 lb "Phat-Sac", I got up and made a pass but it aint very pretty :wink:

07-14-2007, 12:00 PM
I dont think a newer speedo will work Ed. I think the older airguide systems ran through a control unit (black box) and when they had an issue then water would get to the speedo and leak out. If Dr Brian R. checks in hs can shed some light or and older Moomba owner with airguides.


07-14-2007, 01:01 PM
Old Airguides are hard to find. Airguide went out of business a few years ago. You may be able to find a replacement on Ebay or if you are lucky a dealer may have one sitting around. Here is one on Ebay. Seller says they have matching pairs if needed.

http://cgi.ebay.com/ebaymotors/Mastercraft-Airguide-2025-Black-Boat-Speedometer-NEW_W0QQitemZ290139119341QQihZ019QQcategoryZ26451Q QrdZ1QQcmdZViewItem

I have a black Airguide in the garage just in case one of mine goes out but it is the wrong color. I'll need a white faced one as a replacement. Or you could just bite the bullet and install a paddle wheel speedo but you would have to mount the paddle wheel pickup thru your hull.

Hope this helps. I'm on my way to the lake in a few minutes.

07-15-2007, 09:52 PM
My airguides are black faced. all they have is what we used to call in the "old days" is a deep water p/up. A black flip down thingy off back of boat that a small black tube hooks to and goes straight to back of speedo and works off water pressure. I'll ck ebay, or if gent with black dial wants to sell I may be interested. I'm on my way home from my daughters fast-pitch softball tourney in west fl. we won so next week were headed to central fl. "Citrus City" I think... been gone all wk. end so havent had time to pull unit and take a look, will do so tomorrow, thanks again for all response. Ed I'm not familiar with the paddle wheels, are they a hassle to install? where does hole thru hull go? thanks again, bob

07-15-2007, 09:58 PM
mine is just like the ebay one. thanks for the link, it would definetly be the least hassle to replace, just take old dial out mount new one and plug hose to it ! hope they dont go bid crazy :wink: bob phat-sac wells :D

07-16-2007, 12:50 PM
I've got the old airguides on my 98 and I see why they have two speedos...because only one works at a time..lol. I had one speedo not work one day and the next time I launch it works perfectly fine. It's only a matter of time before I start changing them out.

07-17-2007, 08:38 PM
I just pulled the airguide, it has a small almost flat metal diaphram. I havent been able to determine where leak is coming from. AJones you intrested in getting rid of yours? I'm having a hard time getting the diaphram out to inspect it... :? phat-sac bob :)

07-17-2007, 09:40 PM
I am guessing that the 98's must not have the 'black box' MDC controller. All feeds to the gauges in my 99 Mobius are electronic, comming from the controller. There is no path for the water to get to the speedos.

To find Airguide type speedos, where tube goes directly to the gauge, try stores that are more outboard oriented.

07-17-2007, 10:44 PM
Try drying out the speedo and check your hose for air leaks near the speedo as water can only enter the speedo if there is an air leak near the speedo to allow water to come up the tube. It may be a leak where the hose connects to the speedo. Be sure to blow out the remaining water in the hose.

07-18-2007, 08:14 AM
i thought water pressure driving into the p/up off back of boat pushed into diaphram and moved speedo. i can blow air into p/up and it moves the needle, the diaphram acually just expands and pushes on a small rod thereby causing guage to move, it could be very well that the p/up tube is leaking at the hook-up. maybe i can lay down under dash and watch while my boy drives :shock: i have read about them leaking from water staying in them and freezing but that aint happened here lately... (fl.) thanks for all the info guys, I'll keep you posted. bob

07-18-2007, 01:27 PM
The tube should be dry. There is a water/air interface where the water pressure from the pitot tube exerts pressure on the air in the line and then moves the speedo diaphram so the speedo only sees air pressure changes. Water got into your speedo by having a leak either in the speedo or near it where water forced the air out and water would drain into the speedo. Since the speedo is working from your test, I would ensure no more water is in the line by removing the line at the speedo and the pitot tube and blow compressed air from the tube under the dash. Now you have a dry tube again. Reconnect the pitot tube and reconnect (tightly!) the tube to the speedo. If you have any extra tube cut off the old section connected to the speedo and get a fresh connection. My lines are short so I used the plastic tie wrap. I worked on the speedos more than I want to. I even have a handheld basketball pump with the tube connected to it so when the pitot tube clogs (which it does often) I can remove the tube at the pitot and connect the handpump to back flush air through the pitot.