Yanmar 4LHA-STE issue

[Rambler386]

Greetings, I have a Yanmar 4LHA-STE with 600 hours. Was running down the bay at 3000 rpm running great when I suddenly got a low oil pressure alarm and the engine died and will not restart. No noise, grinding, pops, nothing. Oil level is fine and no metal or signs of a catastrophic failure. It turns over fine, though the low oil pressure is on on the panel even with just cranking with starter. Any ideas as to where to start would be appreciated.

Tha ks,

Rambler386

Rambler386

 

[VicS]

Are you sure of the sequence of events ?

Did the low oil pressure warming come on before the engine stopped or did it come on because the engine stopped?

 

[Rambler386]

Definitely came on first, then the engine shut down.

 

[gordmac]

Is there a device to stop the engine automatically on a low oil pressure signal? Sensor fault or actual low pressure? You need to test either or both.

 

[SimonD]

I have the same engine and I don't think there's a device that stops the engine if the pressure drops. Looking at the wiring diagram, there is a sender to the oil pressure gauge and separate oil pressure switch connected straight to the alarm and light on the dash.

The fact that the pressure is low on cranking is not remarkable. Mine takes quite a while to show a reading after it has started. I wouldn't think just cranking it would show much pressure. It also takes a while for the pressure switch to stop sounding after starting. (As far as I know, there is a separate oil pressure sender and oil pressure switch.)

When the engine stopped, did it do so suddenly, i.e. like something seized, or relatively slowly as it does when you press the stop switch? If the former, I'd be worried. However, the fact that it now cranks normally suggests that it's not catastrophic damage. If it's the latter, I'd ignore the pressure alarm issue for now and check the stop switch, relay and solenoid to make sure it isn't activated. Then I'd be looking at the fuel supply.

Hope that helps