Westerbeke loses oil pressure

[Boatelwesterbek]

Hello, I have a 10KW Westerbeke Gas generator. The generator starts and runs good, has 70PSI oil pressure at startup but gradually loses oil pressure over 2 minutes until zero oil pressure and shuts down. This has been checked with a mechanical gauge. Any ideas? Oil relief valve, oil pump, main bearings??
Thanks for the help.

[Lepke]

Not likely the oil pump or you'd never have oil pressure. Also probably not the oil pressure relief valve. While the valve is open when the oil is cold and thick, it eventually closes. But if it didn't, there would still be some oil pressure.
Most likely low oil level or debris/sludge in the oil pan. The engine starts, debris is drawn toward the strainer, eventually plugging the strainer. When the engine stops, oil in the engine, draining back to the pan pushes debris away from the strainer. It also could be the oil filter if the filter type doesn't have a relief valve, for the same reason as the pan strainer.

[Compass790]

+1 for what Lepke said.

[tkeithlu]

Making a scenario out of Lepke's first hypothesis, low oil: Oil is drained into sump. Engine starts up, pump pumps oil, oil pressure. Oil is raised in the engine, pump now sucks air, no oil pressure.

[tkeithlu]

by the way, Boatelwesterbek, welcome to the forum.

Second thought: The world of small engines fit into two categories. Those that measure oil level with the screw-in dipstick screwed in, and those that measure it with the dip stick perched on the rim of the hole. I own two very similar motorbikes that differ on this point. Which is yours?

[jimbunyard]

Change the oil and filter. Let us know what you find...

[Boatelwesterbek]

Thanks everyone for your input and ideas. Will change oil/filter and report back.
Checking oil level with dipstick fully inserted.