Yanmar 315 HP Engine Alarm

[gmberkley]

yesterday during a cruise, the engine alarm came on, none of the lights came on the panel to indicate what the issue may be, I gradually slowed the engine down to 2500 RPM's the alarm stopped, brought it back up to as high as 3400 RPM's and sure enough at some point the alarm went on again, intermittently, but continued to go off, until I got it back down to 2500 RPM's and again, it stopped and didn't come back, the gauges all were normal, and the engine ran perfectly as always, I'll be checking the panel to figure out if any of the lights bulbs are out on the panel, but didn't know if anyone had any other thoughts, I'm many things, a diesel mechanic is not one of them.

thanks for any input

[Tree]

assuming engine temps are normal I will chime in with sea water flow alarm is faulty

[Pitou]

The sea water flow alarm on the Yanmar, though a nice feature, does seem to fault over the years requiring replacement. As stated by Lee / Tree, this is most likely your issue.

Another possibility is that the raw water impeller has spun its hub and the impeller is slipping at higher RPM's. This happened to me in 2019.

September 3, 2019.jpg

[gmberkley]

I'll go with the sea water flow alarm, only because the impellor was replaced over the winter, and only has 6 hours on it...............I hope that is the case anyway, I'll start with that, thank you both.

[gmberkley]

from what I have found, my engine does not have a salt water alarm..............back to the drawing board, I'll have to check all of the lights on the panel, as obviously one should have been lit to coincide with the alarm going off, the salt water alarm light I do have on the dash was blown, so I have at least one other blown, took over 1.5 hours yesterday to find replacement bulbs, paid extra to have them shipped overnight, as without replacing blown bulbs, I don't know how I can determine why the alarm is going off and fix whatever is wrong...........

[Norseman]

Unless your engine is modified it should have a water flow sensor with an alarm.
The sensors wear out and will sound false alarms.
Had it on my Yanmar about a year ago, I will look for the writeup and post a link shortly.

[Norseman]

See this thread and specifically posts from January 25th, 2021:
viewtopic.php?f=5&t=10612

(The flow sensor was worn and replaced, but the problem was elsewhere)

[RobS]

I doubt a 2005 has that flow sensor/alarm. It was eliminated at some point and plugged with a blank. A photo of the top of the engine will tell.

[Norseman]

I doubt a 2005 has that flow sensor/alarm. It was eliminated at some point and plugged with a blank. A photo of the top of the engine will tell.

Aha, they made changes to the engine, sneaky bastards

When they started producing the Yanmars in the US I thought they only changed the designation from 6LP-STE to 6 LPA-STP and the HP from 300 to 315 by rating it at a different intake temperature, everything else be the same.
What else did they change?.
.

[Pitou]

I doubt a 2005 has that flow sensor/alarm. It was eliminated at some point and plugged with a blank. A photo of the top of the engine will tell.

I've been working with Gregg offline from AOG and his engine does not have the flow alarm on his 6LPA-STP. It was originally confusing as he has the Albin panel which has the alarm light marked for it, but the bulb was faulty.

I've searched for the year that this happened and have come up empty, but plucked this photo from BoatDiesel showing the flow alarm location being capped on the 2005 model year.

As Gregg just installed a fresh water flush setup in his boat after off engine raw water service .. it might be a bad idea to put one in and wire it up. With the freshwater flush the sensor should last a very, very long time.

Flow Alarm . 6LPA-STP.jpg

[gmberkley]

I'm going to see if I can find the wiring harness, if it's available, I will remove the plug and install the sensor, I already purchased it, tough little spot to work in I have to say, nothing new there I guess.

[gmberkley]

I can't find, but still looking for the wiring harness for the salt water flow alarm, I still have the alarm and haven't returned it, I changed out every bulb for the indicator lights on the panel, three were not working, not easy finding the replacements. the reason the alarm was going off, the water coolant cap was not tight at all, so the engine was losing water, and couldn't retrieve it from the overflow tank due to the lack of a seal at the cap.............when I idled down the water usage was less, and the boat leveled off, so the water level hit the indicator so it shut off...........one of the two mysteries solved. all indicator lights now work, so if the alarm goes off again, at least I'll know where to start looking.