Yanmar 6LY2A-STP Alarms

HappyKamper

HappyKamper

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Launched today. Very stressful. Engine alarm and 30 knot winds.
Both engines started well. Usually the oil pressure alarm sounds for a few seconds till pressure is recognized, then alarm turns off. Today the alarm sounded and
never turned off.
oil pressure was good
Voltage reads correct
thru hull water pressure is good
Engines were cold, so no overheat
oil level was within standards
transmission fluid was within standards
I'm guessing to check each sensor looking for a faulty sensor?
All thoughts appreciated.
Thank you

Winter work performed was new heat exchangers and new hoses. Engines were started on land prior with water hookup with no alarms.
 
So you have oil pressure guages on both engines that read correctly and independently of each other, change with RPM, but you have an alarm? Probably a snap switch somewhere near the oil pressure sender. Could be a short to ground as well? See the diagram. Given all of the work could be something got discumbobulated. Try disconnecting the wire to the switch and see if the alarm shuts off. It is probably a normally closed switch that opens when it gets minimum pressure. If you tap the wire to the switch terminal it should sound with the engine off and ignition on.

www.manualslib.com

Warning Devices; Oil Pressure Alarm - Yanmar 6LY2-STE Service Manual [Page 184]

Yanmar 6LY2-STE Manual Online: warning devices, Oil Pressure Alarm.
www.manualslib.com www.manualslib.com
 
Last edited:
Thank you boatbum.
Yes I have 2 independent oil pressure gauges that change with rpm’s.
I’m not sure what you mean by a “snap switch”? Never heard that term?
I was looking at that diagram last night and intent to check over each sensor today
 
When conditions are right they snap on or snap off quickly. It was probabaly not the best term for me to use but it's nothing special. On our diesels they used pressure switches on the fuel lines to control the hour meters.
If you disconnect the wire from the switch and the alarm keeps sounding I am thinking there is a short between the buzzer/horn/bell and ground. If it stays on for only one engine I'd focus by the engine initially.
 
So today, I tried disconnecting each sensor individually then starting the engine. Each time it still alarmed. Oil pressure sensor was among the sensors I disconnected.
Thinking that I may have low fuel pressure, I changed both fuel filters. No luck.
I ran out of time to look any further. Next trip back, I’m going to clean any ground wires I find.
Any thoughts are welcome.
 
Off topic but 30Knt winds is a calm day on my lake. 60Knt is a typical day in the spring... :)
 
Phillbo said:
Off topic but 30Knt winds is a calm day on my lake. 60Knt is a typical day in the spring... :)
Click to expand...
That's crazy, 30 was enough for me. Getting in my slip was challenging when your a little rusty from the winter.
 
Did you disconnect the pressure sensor or the switch? There are two related to oil pressure on each engine.
 
I found both. Disconnected each separately. The oil pressure gauge stopped working when I disconnected that wire.
Still alarmed.
Today I am going to check for air lock on the water intake. Long shot perhaps?
Also I’m going to look for any sensors on the transmission
 
I'd stick an ohm meter on the pressure switch wire and see if it is a dead short to ground. Could be anywhere along the line to the alarm and light.
 
I have twin 6LP-STE Yanmars in our Luhrs. I've had this same problem multiple times over the years. Each time I would go through and disconnect each sensor until I found the culprit. The only sensor I've had fail is the raw water flow -- twice.
If you disconnected each sensor individually without finding the culprit then it sounds as if you have a ground short somewhere in the alarm circuit or possibly the alarm itself has failed. Try swapping sensors/connections.
 
Drum roll please…… the problem was not enough anti-freeze. I had the heat exchangers replaced over the winter. When I started the boat on the hard, it was ok. I only ran it for 5 minutes. Between running it on the hard and launch the anti- freeze must have burped? The over flow bottle was half full. Never gave a thought to open the pressure cap and visually look in. Mechanic took about an hour of looking and checking things before he looked. We added almost a full gallon. Alarm went off immediately and boat ran like a champ!
Thank you Boatbum and Bob Ware I appreciate your thoughts.
I think I’m going to make myself a check list of all the possibilities that would give me an alarm.
 
Glad it is resolved. One light and alarm for all of the issues? Ugh.
 
Yes, the boat is a 2004. Before all the electronic “advancements “.
 
HappyKamper said:
I think I’m going to make myself a check list of all the possibilities that would give me an alarm.
Click to expand...
Other wharf rats snickered about my checklists. Notably the "daily startup list" which, while I had a print version, was a memory item. Others only knew I had this list because, if I was interrupted, I would restart from scratch... ( I also had the "shutdown list".

Then there was the "Springizing list", written, and subject to update.

--

Checklists are actually your friend. When I left the dock, I did not have that creepy feeling of, "did I forget something"... And, bonus, I had not forgotten something! ;)

Making the list, and "cleaning it up" so that it is organized and efficient might be a bit of a pain, but that one time pain is less than a trashed day on the water ( or worse! )

Glad you are up and running.
 
That one slipped my mind when I was posting. I know it's there as it, too, has caught me in the past. Glad you are good to go.
 
Don't know about y'all, but I can't remember how many times I had to turn around and check if I closed the garage door! UGH!
 
sugilbert said:
Don't know about y'all, but I can't remember how many times I had to turn around and check if I closed the garage door! UGH!
Click to expand...
U are not the only one... I do it too... We've started a routine when leaving for a road trip. I make a funny face at me wife as the door is coming down so she can confirm to me 20 minutes in to the trip that I closed the door.
 
Phillbo said:
U are not the only one... I do it too... We've started a routine when leaving for a road trip. I make a funny face at me wife as the door is coming down so she can confirm to me 20 minutes in to the trip that I closed the door.
Click to expand...
I have a smart sensor on my garage door. I can tell from my phone anywhere I can get cell service. And water sensors under toilet tanks, RH sensor in crawl space. And more.

And the best sensor is nose of my dog.
 
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