Second, check the oil level and quality. If you haven't changed the oil filter, please do.

Oil and cooling are the two most frequent errors.

You have a bad connection somewhere. 

My approach would be:-

Check wires to the alternator. Check the plugs & sockets on the looms. Disconnect them, spray some contact cleaner on them , then re connect. Waggle all the wires/plugs on the control panels & check for loose ones.

A bit amateurish but sometimes works.

Good luck.

It could be faulty sensor or it could be doing what it is supposed to do! When did you last replace the sail drive seal? We have a Volvo and they say every 7 years, from memory I think Yanmar is a longer interval 

Good luck

Paul

I have  Yanmar 2GM20F with an SD20 saildrive.  The sensor for water between the 2 seals is on the starboard side of the saildrive, just near the seacock.  The normal recommendation is that you can test it by unscrewing it and putting it in a glass of water.  I do this every now and then and ignore the recommendation in my manual that you should replace the seals every 2 years!  I  replaced the seals on my yacht after 14 years,  but my boat is out of the water each winter.

Having removed the sensor, and hopefully no water coming out,  you can push a piece of tissue down the hole to see if there is in fact any water between the 2 seals.

The water sensor only gives a very small signal so there is an amplifier, probably a small box, on the port side of the engine.  Thus there are lots of connections for you to check on a white and red wire.

The water sensor is in the negative side of the alarm circuit, so the other  connection will be a blue negative wire.

I am on my yacht now and, if required, I can take my manuals home and email the relevant diagrams.

Martin

Happy sailing

Long time...

I just had that problem last summer. It was not the sensor that was the problem and definitly not water in the drive seal. If is a short connection in the cables going from the engine to the panel. 

Although, I did change the seal after 18 years of usage. The seal looked like it was new. 

Engine - Yanmar 3YM20 - from 2005. 

That is why we replaced our sail drive seal at Volvo’s prescribed 7 years, why pay for insurance when they have an excuse not to pay a claim, or even tell you what the reduction might be.

As previously mentioned by many, the old seal was perfect, but…….

All the best

Paul

Mine was changed in 2021, as it was then 17-18 years old, but my yacht is out of the water for 5 months each winter.

The estimate was around £2200.  I had always had oil collecting on the round plate of the saildrive and one engineer had assured me that the only place it could come from was from the oil filler cap.  Numerous new filler caps and seals failed to solve the problem.

When a different engineering company pulled the saildrive, they found that the oil seal on the input shaft was worn, hence the oil leak, and it had subsequently damaged the input shaft to the saildrive, so a new input pinion shaft was required.  The final bill was around £2800, which included around 3 man days work.   

I think you just have to accept a big bill is coming and say to the engineers, is there anything else worth looking at whilst you have the engine and the saildrive out where they easily work on it.  Better to spend some money now, than finding you have to replace an engine some time in the future.    

Recently there was an instance here with a Beneteau (40?) that caught a sunken mooring rope round their prop. The rope was strong enough to stop the engine instantly, the resulting torque broke 2 engine mounts and tore the sail drive seal. Fortunately they were still in a busy anchorage and with a quick thinking crew and rapid outside assistance they stopped the boat sinking, but it did result in a lot of internal water damage. 

Unfortunately, in such a scenario, I really doubt any insurance company is going to pay out if they can prove you haven’t replaced the seal as recommended. 

I think you have to add it to the cost of the joys of boat ownership!

All the best

Paul

Johan

Is it not a bit like rigging? you can look at the wires in the length or the bottlescrews & they look perfect. But one does not know what chemical changes has happened within the structure itself. How does one know that the rubber has maintained its flexibility. I do not think that you can do a test just by flexing it with your hands. Perhaps you feel that you can.

I change my Volvo seal every 7 year & note the date on it when I buy it to check that I am not buying old stock to start with. Sometimes I hook things with the prop that really shake the boat ( several times a year in fact) & I do worry that it affects the seal in a way that I cannot see. It might be my imagination, but I reckon the old one is always stiffer than the new one.Is it going hard? Absolutely no idea. I do not suppose anyone else has even thought to compare the old with new.

As for The comment about shaft seal & water ingress by M & R above. I change the seals everytime I change the saildrive seal as a general maintenance item. Just seems a sensible precaution easily done with the drive on the bench. It takes 30 mins to do. 

The solenoid is activeted to stop the fuel supply to the pomp.