Help fixing my speedo

[jamesgreen]

My speedo does not work I thought I could do without it but I can't. Now how do I fix it. I have found where the line goes into the lower unit. If I unhook it there and blow air in toward the speedo it works. Hook it back up and blow air through the hole where water comes in it doesn't work. However I can not seem to get it cleaned out at the lower unit. I have used a small pice of wire and can run it most of the way down but not all the way it lacks about an inch from the hole. Is this a bad desgin or what? Any ideas<br />3.0 liter Merc/Alph 1 in a 176 Crownline.<br /><br />Thanks <br />James

 

[adamk523]

Re: Help fixing my speedo

An air compressor is the best way to clear it out.

 

[Solittle]

Re: Help fixing my speedo

Longer wire??

 

[craze1cars]

Re: Help fixing my speedo

Run the wire into the other end of the hole (the water intake, not the side the hose hooks to)...that's where they plug up normally. The leading edge of the lower unit has a small hole. Keep probing with the wire from both ends and keep blowing compressed air into both ends. Chunks of stuff will likely shoot out one way or the other, and keep going till air is flowing freely through the passageway and no more debris is in there.

 

[monoshock]

Re: Help fixing my speedo

I tought a boat speedo works on vacuum as you travel across the water, maybe I'm wrong.

 

[kenimpzoom]

Re: Help fixing my speedo

After the first few sentences I finally figured out you were talking about your speedometer, not your swimsuit. <br />Ken

 

[monoshock]

Re: Help fixing my speedo

Does anyone really wear one of those things in public.

 

[craze1cars]

Re: Help fixing my speedo

Originally posted by monoshock:<br /> I tought a boat speedo works on vacuum as you travel across the water, maybe I'm wrong.

They're actually simple air pressure gauges. As the force of moving water enters the leading hole, the air in the line compresses. The faster you go, the higher the pressure in the line. They can be easily tested by blowing compressed air and/or a garden hose nozzle into the leading hole and you'll see the speedo move if it's working properly.<br /><br />As for the swimsuits, those can also be tested by using compressed air or a garden hose nozzle. The big difference here is that it's better to shoot it into the TRAILING hole as opposed to the leading hole. If he turns around quickly and knocks the *$*%&^ outta ya, everything is working properly. But if he smiles, you have a serious problem that goes far beyond my mechanical abilities.

 

[thunderroad]

Re: Help fixing my speedo

I just laughed out loud and received a glare from the boss.

 

[jamesgreen]

Re: Help fixing my speedo

My speedo swimsuit is a another issue. We can get to that later.

 

[jamesgreen]

Re: Help fixing my speedo

Thanks I think.<br />I keep working on the BOAT with the wire and air. I thought might be an easier way.

 

[QC]

Re: Help fixing my speedo

Absolutely LOL!!! The crazy 1 stole your bit KIZ, but you get credit for starting it . . . The best part is actually rereading the first couple of sentences, you can get all the way to the design question. Maybe that too.<br /><br />As I type I am getting tears . . .

 

[craze1cars]

Re: Help fixing my speedo

Hey James...my apologies for getting a tad stupid here. I'll get back on topic now to see if we can offer some REAL help:<br /><br />1. Obviously you found the hose and were able to disconnect it from the lower unit to test the gauge with air pressure. So the blockage is somewhere between the hose hookup point and the water intake.<br /><br />2. With the hose disconnected, blow compressed air down into that hole. Does the air come out? There should be a forceful stream of air shooting forward out of a small hole that looks like a gouge in the lower unit. It's probably 6 inches to a foot below the hole you have the air gun on, facing toward the front of the boat. Do you understand where this hole is? It's kind of difficult to explain location without posting a picture, and I'm a little to lazy to go snap one of a lower unit right now especially if you don't need it...but I'm glad to do so later if you need the guidance.<br /><br />Please don't be offended if you feel I'm dumbing this down too much, just trying to understand exactly where you're at in trying to clear this thing out.

 

[AMD Rules]

Re: Help fixing my speedo

The small diameter hole on my 60 Merc was plugged with what looked like wet wood pulp preventing the speedomoeter from operating. I tried several ways to remove the debris, but in the end this is what worked: <br /> <br />Using a hand pump, hook up an open end of the speedometer tube on the lower end and apply moderate air pressure. I found that the attachment used to inflate water toys fit into the tubing well. Find the appropriate size drill bit to fit in the pick-up hole (3/32"), and rotate it with your fingers when inserting it into the hole. When it is in as far as it will go, begin to pull it out while applying the air pressure. The flutes on the dril tend to grab onto the debris, and should pull the debris clear from the hole. The air pressure helps to pursuade it, and you be greeted with a rush of air as the debris finally pops out of the hole.

 

[jamesgreen]

Re: Help fixing my speedo

It's all in how you word the question. <br />I have found the intake hole and can not seem to make any progress. The drill bit sounds like a good idea if I don't screw anything up.<br />Just for the record I do not wear a speedo.......<br />without a bikini top

 

[craze1cars]

Re: Help fixing my speedo

Another thought, unless others see a problem with this...it might be clogged up with hard water deposits. Possible solution would be to have the speedo hose removed, motor trimmed down, dribble in some diluted muriatic acid into the top hole, and let it do it's thing while it soaks for a while. Should eat through the garbage and eventually dribble out of the intake hole.<br /><br />I have no other suggestions...that passage needs to be cleared or it'll never work. Good luck!

 

[jamesgreen]

Re: Help fixing my speedo

c1c,<br /> well I tryed that ate the back right out of the lower unit. Just kidding. I thought about Drano out of an eye dropper but I'm like you I need some more info.

 

[craze1cars]

Re: Help fixing my speedo

See whatcha get for seeking on-line advice from a bunch of idiots?!? Big ol' cooked hole in yer oudrive! Funny.<br /><br />Anywho...I'm quite serious about the muriatic acid. It's dirt cheap, and used heavily in the industry to get hard water deposits off of the outside of the boat and outdrive, so I frankly wouldn't hesitate to use a dropper to squirt some into the top hole to see if it starts smokin' and fumin'. I've done it before and I'll generaly dilute about 2 parts water to 1 part acid and it works nicely for wiping clean a crusty old boat. So if you squirt some in the hole and see a reaction taking place, that's good because you know it's working. Let it cook for a while and then hose it out with plenty of fresh water to neutralize the acid. If it were mine, I wouldn't hesitate to try it IF you think maybe the problem is hard water deposit buildup. If it's something else, the acid may not even react with whatever it is and you'll gain no ground. Either way, I really don't think it can hurt a thing (famous last words,right?!) after all, there's no moving parts in that passageway, it's just a simple pipeline.<br /><br />I'd also strongly suggest you post this same question in the "Mercruiser repair" thread of this forum. Actual boat techs frequent that specialized forum more frequently than this general boat section, and I'm sure this is not an uncommon issue that someone over there can help you with. Hopefully that helps.