Yanmar Dipstick Yields Strange Results !

[bchaps]

My engine is a Yanmar 4JH2E...starts at the touch of the key and is very dependable. We're currently running the ICW about eight hours each day with RPM averaging between 2200 to 2800. However it has one quirky habit: while checking oil the initial dipstick pull shows an oil reading nearly a quart low. If I wipe the stick and re-test, all subsequent readings are on the mark. On one occasion I added a quart based on the initial pull and later found I was running with an extra quart in the crankcase. Any ideas why the initial pull is lower?

Thanks,

Bill

[smallyachts]

Interesting. Our 4JH2 does the same thing. If I check it before we run it, it shows a little low. If I check immediately after running it, it shows a little low. But if as you said, wipe the dipstick and recheck it, it shows an accurate level.

I can understand the difference in readings from immediately stopping and checking, then rechecking after wiping the dipstick. I am assuming that it takes a few seconds for the oil to drain back out of the upper galleries and cooler.

What I don't understand, is why after it has been sitting for a week, the initial check shows low, but then after running for a few minutes, and checking it again, it shows an accurate level.

Which brings up another question. Anyone know where to get the parts (NLA from Yanmar) to rebuild the oil feed line to the injector pump? Ours has rotted out from a previous leak from the cockpit sole, dripping on the steel line. Yanmar still has a part number for the smaller banjo fitting (injection pump side), but they no longer have a part number showing for the larger banjo fitting (block side).

[boatman61]

Heat expansion....

[DaleM]

I've got a Universal diesel engine that also has low oil on the dipstick after running. Someone explained it to me:

The oil pump pulls the oil down in the sump, the oil level on the dipstick drops and the dip tube fills with air. Shut the engine off and the oil fills the sump but the seal at the top of the dipstick tube keeps a bubble of air trapped and doesn't let the oil rise. Pull the dipstick and it is low or empty. Wait, put it back in and since the seal was broken, the oil has risen in the tube. It's magic! One of life's little mysteries!

Now if I could figure out how to make it warmer, like it is supposed to be, in the south!

Dale

[smallyachts]

That makes alot of sense.

So, if I pull the dipstick up just enough to break the seal after running the engine, then a few days later push it all the way back in before starting, I should see an accurate result.

Will test this theory later today, and will recheck in a couple of days.

That would be one little worry out of the way. Then all I have to do is worry about the JB Weld repairs to the rotted oil feed line.

[YOGAO]

That is exactly correct. That is why the standard procedure for checking the oil level is to pull the stick, wipe it, fully re-insert it, pull it and check the level.

[sailorboy1]

low oil on the first check is most likely due to not getting the stick all the way seated/in the tube

a quart low is a lot of oil, but not very far on the stick if it isn't all the way in

[Blue Stocking]

If I may stray a bit, how do you determine the position of the oil level on the dipstick, in relation to the installation angle of your engine.
My engine is at about 10 degrees, I think it is, and if I fill to full on the dipstick, which is at the high end of the engine, I will have more than the 7quarts spec'ed for a horizontal sump.
I then get aft-most cylinder wall oil splash, and a bit of blue smoke.
Pump pick-up is at the lowest end of the sump, oil pressures and temps are good.

[AnchorageGuy]

Originally Posted by Blue Stocking

If I may stray a bit, how do you determine the position of the oil level on the dipstick, in relation to the installation angle of your engine.
My engine is at about 10 degrees, I think it is, and if I fill to full on the dipstick, which is at the high end of the engine, I will have more than the 7quarts spec'ed for a horizontal sump.
I then get aft-most cylinder wall oil splash, and a bit of blue smoke.
Pump pick-up is at the lowest end of the sump, oil pressures and temps are good.

This is typically done at the time of installation and most all Yanmars we have installed had no markings on the dipstick. Once the crankcase is full of oil, the dipstick is marked. If you doubt yours is correct, do an oil change, be sure and get ALL of the oil out of the crankcase and refill it. Before you start the engine again, check the stick and remark it if you need to. Chuck

[Captain Bill]

Sorry Don, but DaleM has it right. Blue Stocking, I'm not sure what kind of engine you have, but Yanmars have their dipstick near the center of the engine where tilt makes little difference in the oil level on the dipstick. My engine service manual states design limits for the installation angle, perhaps yours does too. Most diesel sumps actually hold much more oil than the engine needs to run. My manual is on my boat, but if I remember correctly the minimum oil level is two or three quarts, but it holds 6 quarts (5.5 liters). I'm not recommending running it a quart low, but at your installation angle a bit low on the dipstick probably won't hurt at all.

[simonmd]

I have Detriot diesels, I know the oil needs topping up when they stop leaking!

But yes, NEVER take the first reading and always check when warm. Pull out, allow any air lock to be released and reinsert to get an acurate reading.

[sailorboy1]

Originally Posted by Captain Bill

Sorry Don, .............. I'm not recommending running it a quart low, but at your installation angle a bit low on the dipstick probably won't hurt at all.

I never said to run it a quart low. That would be crazy.

[Hudson Force]

Originally Posted by DaleM

.....The oil pump pulls the oil down in the sump, the oil level on the dipstick drops and the dip tube fills with air. Shut the engine off and the oil fills the sump but the seal at the top of the dipstick tube keeps a bubble of air trapped and doesn't let the oil rise.......
Dale

I never thought of this dynamic. Thanks for the insight!

[lancelot9898]

Originally Posted by Blue Stocking

If I may stray a bit, how do you determine the position of the oil level on the dipstick, in relation to the installation angle of your engine.
My engine is at about 10 degrees, I think it is, and if I fill to full on the dipstick, which is at the high end of the engine, I will have more than the 7quarts spec'ed for a horizontal sump.
I then get aft-most cylinder wall oil splash, and a bit of blue smoke.
Pump pick-up is at the lowest end of the sump, oil pressures and temps are good.

I have the Perkins 4-108 and when I first bought the boat new back in 1985, the Perkins merchanic told me to fill the oil higher than the marking shown on the dipstick. In fact it was quite a bit higher than the max level mark. I have always filled to this higher level and the engine is still ticking. I would guess that the engine is at least 10 degrees off the horizonal. (maybe more)

[Captain Bill]

Originally Posted by Don Lucas

I never said to run it a quart low. That would be crazy.

Sorry Don, I didn't mean to imply you were suggesting running it a quart low. I was responding to Blue stocking and noting that if he puts in the specified number of quarts he is not running a quart low even if it is indicated on his dipstick because of his installation angle. I was also pointing out that most diesels have a minimum oil level that is substantially below their full capacity. This means that adequate lubrication is possible even a couple of quarts low. Even if because of his installation angle the dipstick reads low he probably has adequate splace lubrication to his forward cylinders. I'm sorry if I did not make myself clear on that. This assumes of course that his installation does not exceed the maximum angle specified for his engine.