Full or empty of oil, Yanmar 3YM30

[pierrrre]

Good morning,


I need some words of wisdom. I own a Lagoon 380 powered by 2 Yanmar 3YM30. When I check the oil levels with the engines cold, the dipsticks always show empty. After wiping them off and reinserting them in the engines to check the oil level again, both dipsticks show the oil levels as full. It doesn't make much sense to me. Is this normal and the oil levels are OK or should I start panicking....?

[pierrrre]

Never mind, I found the answer on Youtube. The oil level is not accurate the first time around. Never having taken a 3YM apart, it still doesn't make much sense to me though. Panic averted....

[capt jgw]

I've had engines that did that. Apparently when running the oil pump pulls the oil out of the dip stick tube and the rubber seal at the top prevents it flowing back in. When you pull the stick out the first time it breaks the seal and lets the oil back in. Due to the cold oil's viscosity it doesn't happen quickly.
When I was a kid my dad taught me that you could check the oil on a cold car engine by just pulling the stick out and reading it and you didn't need a rag. But those didn't have the seal at the top of the stick and I don't think the tube went down as far into the engine block. .

[JoeRobertJr]

Originally Posted by capt jgw

I've had engines that did that. Apparently when running the oil pump pulls the oil out of the dip stick tube and the rubber seal at the top prevents it flowing back in. When you pull the stick out the first time it breaks the seal and lets the oil back in.

Thank you for the excellent explanation for the OP's observations.

[Avionics_Joe]

What I do is first pull the dipstick out 2 inches, then check the belts and water. Shove the dipstick back in, then pull it out to take the reading.

[EmeraldCoastSailor]

Running the engine must siphon oil from dipstick tube. Mine does same thing. Makes it nice in that you don’t need a paper towel to check oil level. Pull it out about 4”, then check strainer, and then push back in and pull out to check oil.

[Phyrcooler]

Originally Posted by capt jgw

I've had engines that did that. Apparently when running the oil pump pulls the oil out of the dip stick tube and the rubber seal at the top prevents it flowing back in. When you pull the stick out the first time it breaks the seal and lets the oil back in. Due to the cold oil's viscosity it doesn't happen quickly.
When I was a kid my dad taught me that you could check the oil on a cold car engine by just pulling the stick out and reading it and you didn't need a rag. But those didn't have the seal at the top of the stick and I don't think the tube went down as far into the engine block. .

Lol… my 3YM30AE is the same. I knew to pull and reinsert… but like others always thought it weird and wondered why. It just didn’t seem logical. Now it is so obvious I almost feel stupid for not figuring it out previously!

[pierrrre]

Thanks for the explanation Capt jgw. Makes sense now.

[misssherry]

So the dipstick tube is as long or longer than the dipstick? I had always assumed that the dipstick arrived into the oil sump without being guided all the way by the tube.

[Searles]

The difference in dipstick tubes is that some on various engines is used to connect the oil removal pump to ,others use the tube to guide the oil removal tube to the low point in the sump ,the dipstick on the engines with oil removal via the tube ,which goes to the sump low point ,the dipstick is in the tube all the way .

[Emmalina]

I was always taught to pull the dipstick wipe it then put it back in to get a reading as so many conditions may produce a false reading. That was 50 years ago LOL