Checking Oil

[casual]

I,have a new old boat getting aquainted with.I,am preplexed,when checking the oil when cold after sitting overnight the oil is barley present on the dipstick,I,wipe the stick and reinsert remove the oil shows up to the mark,I,ran a thousand miles repeating this process and it was always the same.I,never added oil in all thoese miles,any ideas,The engine is a Yanmar 4jh3e 56 hp 2002 with appx 3000 hours,no smoke and lots of power.
Thanks Dave

[Ziggy]

After you reinsert the dipstick, try waiting 10 min or so before you pull it out again to check the level. The cold oil seems to take its time to flow up the tube around the stick.

[hellosailor]

When sitting overnight, the oil SHOULD be all the way up the stick, since it was warm and easily flowing before it got cold.

My first thought would be to check with Yanmar on how long the correct dipstick should be--you can never assume the original parts are on an old boat.

Why it would show a higher level after it warmed up...that does seem odd, another question to ask Yanmar unless someone pops up with an answer.

With a "new old boat" you might also want to send out an oil sample for analysis. This will give you a baseline of what is in the oil, whether bearings are taking wear, many interesting things. Once a year for $25, and you'll know what's happening in the engine, long before it becomes a problem.

[Hud3]

Dave,

I had the same engine, 2001 model. Had the same experience with the oil not showing on the stick after the engine sat overnight, but showing right at the mark when re-inserted. I never could figure out why, but came to the conclusion that it wasn't a problem.

[noelex 77]

Don't worry. The Yanmar engines seem to to do this.i can only assume that there is a vacuume that sucks some of the oil out of the dipstick.

[FraidNot]

My 4JH3E has the same indication.
Not a bother in my view - the reading on the second 'dip' is the correct one.

[casual]

Thanks Guy's I'll chalk it up to ONE of the mysterys of life.Fortunately I,checked it a second time before adding oil.All's well

[Safari38LH]

Me too. First reading always negative. Second reading right on. Third reading oil everywhere so basically no reading. I always thought it was something to do with pressure. Maybe when the engine cools from the last use is forms a vacuum in the dip stick tube? I always wondered.

[Nemo55]

The fault is at the dipstick tube being too long ,,it needs to expose the dipstick rod to the oil in the pan, instead of the oil in the tube.
What happens is upon cool down you get a partial vacuum within the crankcase,,which draws the oil out of the dipstick tube,,kinda like ending up with an airbubble.
Then when you pull the dipstick you are equalizing the pressure from outside of the oil pan, thereby allowing oil to once again enter the tube.
Easy way to fix this is to pull the tube assembly and nip off about half an inch below the flange..then remount the tube. Problem solved.
Either that or just live with it,,as it really isn't that big of a deal.

[David M]

As air cools it contracts, which would draw the level in the tube down.

That's my theory at least.

[WrenchBender]

This is common in any engine. Any mechanic will tell you to pull the stick, wipe it, reinsert.....pull and read. This is the proper method hot or cold for any engine with an oil reservoir.

[bobconnie]

WrenchBender +1Absolutey Right