Oil checking question

[hlev00]

I have a Yanmar 4JH4E on a 2005 Beneteau. It was new to me last fall. I have been checking the oil regularly but there is something odd to me in the way the oil level shows up on the dip stick. When I pull it out before starting the engine the oil level looks low by almost a quart. But when I reinsert the dipstick and check the level again, the level is where it should be. Reinserting and checking again regularly shows the same good level. It has been this way since it was serviced by a mechanic in the spring. It seems to me that the correct level is when I first pull it out.

Does this sound familiar and which level is correct?

Thanks,
Harry

[westwinds]

I have seen this happen checking oil level, that is it seems to be up where it should be, but if turn the dipstick around so I am looking at the back side, I will see that the level is low. I think what might be happening is the first time you pull the dipstick, oil is sticking to the dipstick and is pulled up into the dipstick tube. If you then check the level again, the oil trapped in the tube sticks to the dipstick and makes the level seem where it should be, near the top, but it is actually low. When you first pull the dipstick, use that level for adding oil. By the way, when the engine is cold, if you start it up and then shut it down while it is still cold, oil will stick to the internal parts of the engine and will make the level seem low; however, if you wait for the oil to drain off the engine surfaces back into the oil pan, you will have the correct oil level.

[Ziggy]

It is the same with my engine (Yanmar 3YM20). The proper oil check procedure (according to the operation manual) is:

1. Turn off the engine
2. Wait minimum 10 minutes
3. Take out the dipstick, wipe it off, and reinsert fully
4. Take it out again and check the oil level.

Typically, when you take out the dipstick the first time, it may not show any oil! Don't panic, wait a minute, reinsert it, take it out and check it again. This is the "true" oil level and it will probably show all is well.


I saw somewhere (don't remember where) that you should also unscrew the oil fill cap while checking the level. If you do that, make sure that you remember to screw it back in.

[noelex 77]

Same engine here with the same weird dipstick. The correct reading is after 10mins after removing and reinserting the dipstick.

Wait the full 10 mins for an accurate reading. About 2 mins after it stopped the oil level on the dipstick sometimes starts going down, unlike every other engine I have used where it slowly rises as oil runs back into the sump.

[jeremiason]

Many experts recommend checking your old cold, so that you get an accurte picture of the oil level.

Like everything else, oil expands when it is hot and the reading will be effected to a varing degree.

[delmarrey]

If you notice the dipstick has a rubber cork at the top and the tube extends all the way to the bottom of the oil pan, which creates a vacuum in the tube as the oil cools.

Here's the tag that comes on yanmars dipstick.

.

[sartorst]

In some engines the dip stick tube is below oil level on the bottom of the tube, air is trapped in the tube until you break the seal at the top of the tube

[seadrift]

Further to this problem, the bend at the bottom of my 3JH2E dipstick must be so acute that it constricts flow when evacuating oil with a vacuum pump. I have to repeatedly withdraw the pump tube from the dipstick, reinsert, and re-pump. Oil changes take for ever...

[noelex 77]

Originally Posted by seadrift

Oil changes take for ever...

Don't forget to remove one of the filer caps so air can get in.
Not that I have ever made that mistake myself, you understand

[seadrift]

Good point to emphasize that. Nevertheless, still a problem with that done...

[hpeer]

I was too embarrassed to post this question! I have the same issue with same engine. Also I was concerned of putting in too much oil.

What convinced me was watching oil pressure at idle, if it dropped at idle I reasoned there was too little oil.

So now I keep oil in top half of dip stick measurement, and disregard the first reading. Take it out, wipe it off, put it in, read it.

Gotta love yanmar on this one.

[hlev00]

Originally Posted by Ziggy

It is the same with my engine (Yanmar 3YM20). The proper oil check procedure (according to the operation manual) is:
...

The operation manual? What a concept.

It sounds like air pressure in the small dipstick tube prevents the oil from seeking the same level as in the engine. When the top of the tube is opened up by removing the dipstick the first time, the oil can seek the same level as in the engine, giving an accurate reading.