Alarm upon starting Yanmar

[ALICE J]

Since owning my 2011 R27 for 6 years, when I start my 4BY180 the alarm for the engine would sound when I turned the key, as the engine started the alarm would stop. Recently after trailering the boat back from Kentucky, I put the boat into the water. As I started the engine, the alarm sounded, said check engine. (yep the engine was still there!) Stopped the engine and checked the oil, belts, water, all good. Next started the engine had good oil pressure, water flow. I let the engine run for perhaps two minutes, then the alarm stopped. Curiously when I start the engine the alarm momentary stops, then resumes for perhaps two minutes, then shuts off. Where is the alarm sensor, is it in the oil pressure switch? Where else should I check?

 

[Brian B]

There are quite a few older posts on this subject, search Yanmar Alarm.
The system is dependent upon good clean ground connections. Check and clean all ground connections from the battery to engine block and ECU. When the oil pressure switch starts to fail it gives unusual pressure readings.

 

[vertigo]

Since owning my 2011 R27 for 6 years, when I start my 4BY180 the alarm for the engine would sound when I turned the key, as the engine started the alarm would stop... Where is the alarm sensor, is it in the oil pressure switch? Where else should I check?

On your BY-series Yanmar engine, the oil pressure sender is mounted to the bottom of the oil filter base via a banjo fitting. It is an on-off switch that will close at approximately 7psi. If that sender fails or has poor grounding, then it will trigger an annoying alarm.

 

[vertigo]

When the oil pressure switch starts to fail it gives unusual pressure readings.

Not exactly. The oil pressure readings are provided by a separate oil pressure sensor, which is mounted on the top forward starboard corner of the engine under the vanity cover. That sensor provides resistance output to the instrument cluster which calculates and displays a pressure reading from the resistance.

The oil pressure sender has only two states: open and closed.

 

[knotflying]

That "Check Engine" waning is so useless. I would get the code to see exactly what it may be trying to tell you. There is a button sequence to press to get the error codes. I can't remember it off the top of my head. As Brian said, make sure all your grounding is perfect. I even ran an additional ground directly from the engine battery to the engine block. There are also a positive and negative wire from the engine battery to the ECU. Clean them up. See what happens after the cleaning. If you are still getting it get the codes for a better detail of the possible issue.

 

[Irish Mist]

There is a way to get a code to see what the alarm is about.. It’s in the manual I believe... I have seen more then once an alarm caused by a worn out glow plug.. I am far from a mechanic but on my 29 Yanmar there is a connection to the rear and lower ( I believe under ) port side of the engine. You can try unplugging and see if it fixes the alarm. The engine will still start with out the glow plugs.. But works better with them..
Good luck finding the issue but to me sounds like the glow plug as it comes and goes..

 

[knotflying]

There is a way to get a code to see what the alarm is about.. It’s in the manual I believe... I have seen more then once an alarm caused by a worn out glow plug.. I am far from a mechanic but on my 29 Yanmar there is a connection to the rear and lower ( I believe under ) port side of the engine. You can try unplugging and see if it fixes the alarm. The engine will still start with out the glow plugs.. But works better with them..
Good luck finding the issue but to me sounds like the glow plug as it comes and goes..

Interestingly I had that alarm once, but it did show on the screen the issue. And yes, disconnecting the module eliminates the issue.

 

[ALICE J]

Up date on the alarm. I found the wire that comes out of the bottom of the oil filter. It has a connector plug. I pulled the connector apart and found oil and perhaps water inside the connector. Cleaned with WD 40, and contact spray cleaner and reassembled. Will find out if that worked in a few days.

 

[j&lgray]

Having experienced some engine alarm issues, one point to those who have the Yanmar engines is the value of the engine display module on the dash. There are four soft key buttons on the display. When the engine alarm sounds, press the button on the far right and it will show which sensor is the cause of alarm. The alarms re-set when the engine key is turned off.

There is a barrel connector of about 10 sensor wires before the Electronic Control Unit. This harness should have been mounted in a more waterproof location. It is under the deck but next to the engine hatch opening. On my engine, this barrel connector has been the cause of multiple alarms when moisture and corrosion gets in. The fix (taught to me by a Yanmar-paid Technician) is unscrew the barrel connector, spray with brake cleaner, and exercise the connection by connecting and un-connecting the the whole barrel connector assembly. This breaks free the corrosion. For me, this has worked every time.