YSM8 - Overheat horn

[csoule13]

The following has happened a few times now with my Yanmar YSM8.

Start up at the slip, cooling water starts belching out the exhaust, the overheat horn stops almost immediately.
Go motor for some time without issue. Shut down engine, sail.
At some point, turn the engine back on. Overheat horn does not go off for anywhere from 10-30+ seconds, despite cooling water belching strongly out the exhaust.

Yesterday, I shut the engine off after 30, 45 seconds, and confirmed the seacock was fully open(it was) and the strainer was clear of debris(clear), and restarted. The horn stays on for about 10 seconds and blessedly goes quiet. We motor in uneventfully.

Is this just an engine that is still toasty from earlier operating in the Chesapeake in August?

All of that, and the promised 10-15 kts of wind was eaten by a tstorm that blew threw just before we headed out. At least our guest, who hadn't been on a sailboat since he was a child, loved being on the water regardless of conditions.

Thanks everyone!
Chris

[Joe CD MS 300]

Chris, since the issue appears to be intermittent, it may help to get one of those infra red temperature reading guns (they might be $25 at Harbor Freight). Make a chart of 5 or 6 locations on the engine block and heat exchanger. A couple of position on the head and engine block and the inflow and outflow pipes / hoses on the heat exchanger. Mark the spots with a sharpie so you can consistently check the same spots. Record the readings at when the engine has warmed up and the alarm is not going off. You should now have base line to check when and if the alarm. It should give you some peace of mind to confirm that the engine is not overheating when the alarm is going off (assuming there is no overheating issue.

In the long term maybe consider adding a temperature gauge? Maybe there is a kit available for the engine?

I can’t take credit for this procedure, I believe I read it on MaineSail’s website.

Edit: this is a link to Mainsail’s article:
https://marinehowto.com/engine-temp-mon ... ssessment/


Joe


Joe

[bottomscraper]

I've never owned a YSM8 but on most diesels the buzzer that goes off when you first start the engine is not "overheat" it is "low oil pressure". Sometimes the same buzzer is used for both but the thing that triggers it at start is low pressure. When the oil is warm it is thinner and may take a bit longer to get up to working pressure. Do you have an oil pressure gauge?

[csoule13]

I've never owned a YSM8 but on most diesels the buzzer that goes off when you first start the engine is not "overheat" it is "low oil pressure". Sometimes the same buzzer is used for both but the thing that triggers it at start is low pressure. When the oil is warm it is thinner and may take a bit longer to get up to working pressure. Do you have an oil pressure gauge?

And of course, if I had started with the service or operations manual, I'd have realized the horn is linked to a few different items. The panel, such as it is, has a few lights of which I'm pretty sure are not operational, the horn, a starter button and the key. It's pretty minimal.

Thanks everyone, this gives me much more to work with and much less to fret about.