Speedometer Inop on My New Boat

[Knot Waiting]

Yesterday I was able to take my new boat out for her maiden voyage. Everything went well except that the speedometer doesn't work. It's a 1991 Sea Ray 260 Overnighter, Mercruiser 7.4 454 Mag, Bravo 1. All the other gauges function (except the depth finder, go figure) and the drive is in cherry condition. I am coming off a 7 year Alpha 1 affair so this is all new to me. Any suggestions on where to start or how this unit works? Thanks.

 

[TilliamWe]

Re: Speedometer Inop on My New Boat

Start here, this is the pickup in the front of the drive, it gets clogged easily and often:

And this is the tube/fitting in the front of the anti-ventilation plate, it gets broken or detached:

 

[Don S]

Re: Speedometer Inop on My New Boat

Is the speedometer hose hooked up to the drive? Is the pitot hole in the lower unit plugged up?


Here is from the Bravo service manual

 

[QC]

Re: Speedometer Inop on My New Boat

Probably not specifically a Merc issue, but it could be . . . First thing to do is see if the gauge works at all. Remember these are actually air pressure gauges, water jams into the hole in the front of the drive, squeezes air in the tube that runs to the speedo head, air pressures rises as speed increases. If the hose is not connected at the head, or there is a leak somehwere, then no bueno. If you can blow into the hole in the back of the gauge you can see if the needle moves. If it does, then check to see if there is anything jammed into the little hole in the front of the drive (actually look at this first). If the gauge works and the hole is clear, then there is probably a leak in the line that runs from the drive to the speedo head. Or the connector on the drive has come loose or off.

Edit: Bunch of simuls . . .

 

[Knot Waiting]

Re: Speedometer Inop on My New Boat

So the water pick up is just a hole/slot above the front of the torpedo housing on the lower unit? That explains why there is no remote pick up hose bolted to the transom like on my old boat.

 

[Don S]

Re: Speedometer Inop on My New Boat

It's not a slot, just a small hole in the leading edge of the drive.

 

[Knot Waiting]

Re: Speedometer Inop on My New Boat

It's not a slot, just a small hole in the leading edge of the drive.

Ok. Looked at TilliamWe's pic a little closer and see what you mean now. What's the best way to clean it out if it is plugged? Is it safe to send a small wire up to break up the debris or is there a better method? Think I'm gonna have to do some reading up on this unit, it's pretty different from the Alpha I'm used to.

 

[Don S]

Re: Speedometer Inop on My New Boat

What's the best way to clean it out if it is plugged? Is it safe to send a small wire up to break up the debris or is there a better method?

Did you even look at the pictures I posted ??????

 

[Knot Waiting]

Re: Speedometer Inop on My New Boat

Did you even look at the pictures I posted ??????

Yikes, looks like my extra long weekend killed a few too many brain cells, lol. Sorry about that, I saw them but didn't read everything. I'm gonna do that when I get home. Thanks

 

[Knot Waiting]

Re: Speedometer Inop on My New Boat

UPDATE:
Checked out the pick up and found the hole was plugged..... with wood? Odd. Anyway, I slowly and carefully drilled it out with a tiny bit and water flowed back out so hopefully this fixes it.

 

[TilliamWe]

Re: Speedometer Inop on My New Boat

Get used to that procedure. You'll be doing it a lot, if you actually use your boat often.

 

[OFD4546]

Re: Speedometer Inop on My New Boat

How accessible is the connection of the hose to the transom assembly?