Yanmar engine alarm on start-up until 120 degrees

My R-25 has a weird problem with it's new Yanmar 150hp 4BY which was replaced in 2012 (remember that little oil pipe breakage issue…). Got around 70 hours on this new engine.

Upon turning the key to the first position, the glow lamp lights and then goes out and the ear splitting audible Engine Alarm comes on with the display saying "Check Engine" even though the engine is not running. The display offers no other help. The alarm stays on if I re-start the engine until it heats up. Once the temperature reaches exactly 120 degrees (or more), I can turn off the engine and restart it without the alarm going off. Won't work if I try this at ≤119 degrees.

I can run the boat normally, start and stop the engine all day without problem as long as the engine temperature does not sink below 120. Trying to restart the engine while its temperature is ≤119 results in the Engine Alarm coming back on until it warms up to 120 and I stop and restart. I live with the ear splitting alarm for up to 10 minutes until 120 is reached, but this certainly isn't working right.

This problem happens 100% of the time; i.e., it does not fluctuate. I tried disconnecting the batteries to the engine and then reconnecting them thinking that might re-set the ECU. No luck. The good folks from Mack Boring (our Yanmar distributor in New England) were convinced it was a bad heater module, but installing a new one did not help. Any ideas?

Jerry,
There is supposed to be a code that can be read from a module that plugs into the engine computer. I would assume Mack Boring would have done this and started to hone in on what may be causing the problem. It sounds like an erroneous error which is affected by low temperature. Sorry I could not have more info on this. Did you try Peter over at Winter a Island Yachts? He may have some insight.

We have the same issue and the codes that show up on the scanner are all related to the glow plugs and the glow plug controller. When the engine temp reaches the set point for the glow plugs the alarm drops off the display but the event is still recorded by the engine ECM. Ladybug, Too is at the Yanmar dealer's shop and we hope to isolate the issue. It is likely a connection that is not making adequate contact. I am not sure what glow plug controller you have but if you can disconnect it, do so and see what happens. Also when the alarm sounds depress the first and next to last display buttons simultaneously to see if you can silence the alarm. If your alarm light glows at a low level even when everything is O.K., Yanmar has a bridge diode plug in that will correct that condition.

Pat & Carolyn, Ladybug, Too

Thanks for all this information. When the weather warms up I guess I'll tow the boat up to Mack Boring which has a small service bay, and share with them the Ladybug info. which should put them on the right track. Might as well have them stick in a new impeller, too! Thanks, again.

PS. Especially thanks for the trick that might silence that alarm! I spent a couple hours wandering around Edgartown stopping here and there and only noticed the toilet paper stuck in my ears when I saw it hanging out 6" on both sides in the head's mirror, AFTER I returned to the boat. What must the hoity toity Edwartown folks think of us tugnuts, given me as your representative! I'm deeply regretful. No wonder I never hardly ever get invited to a rendezvous.

uuuuh, if you promise to wear the toilet paper ear plugs for happy hour, you are invited to the Florida gathering in Feb. :mrgreen:

I guess everyone could recognize me that way! It'd be my 1 minute of fame, anyway. I like to consider myself a "fashion risk" so the TP would likely complement by attire. Wish I could get Alto back down to Florida for the rendezvous–maybe next year!