Yanmar 4JH oil change puzzle

[a64pilot]

Originally Posted by delmarrey

There is a breather valve in the center of the rocker arm cover. It sounds like you need to clean it or replace the diaphragm.

On mine, no diaphram, just screen wire stuffed in there, (4JHE)
However, the dip stick does have a very good seal at the top of the stick, when you turn the warm engine off and let it sit awhile, the air trapped in the dip stick tube cools and draws oil up into the tube, resulting in a false high reading, second time you check it, it should be a lower and correct level though. But for some reason my stick reads differently on one side than the other, I assume this is from the stick touching one side of the tune as the tube is curved,but that's just a guess.


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[lovinlifebda]

I have the same issue on our yanmar where the oil shows a different level on each side of the stick. My assumption was to take the higher reading as the actual level but have always been puzzled about how it happens. Always figured it was just some quirk of my engine......love coming across information like this on CF.

[a64pilot]

I think the oil level changing is due to the tube going down under the oil level, on an automobile the tube doesn't end under the oil level, so it wouldn't suck oil up the tube


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[Charlie]

Del so am to understand correctly that we should use the volume of oil as opposed to the dipstick level. Mine is at an angle but I don't know how many degrees. Next oil change I am going to empty it completely of oil. Then I will carefully measure the amount of oil that I put in until it is filled to the recommended level. From there I will remark the dipstick. I guess I have not been keeping the proper amount of oil in the engine since new.

[a64pilot]

At least on my engine the dipstick is centerd, meaning at least in pitch the stick will read correctly.
I'd at least call an expert, say the people a Mack Boring to see what they say.


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[delmarrey]

Originally Posted by Charlie

Del so am to understand correctly that we should use the volume of oil as opposed to the dipstick level. Mine is at an angle but I don't know how many degrees. Next oil change I am going to empty it completely of oil. Then I will carefully measure the amount of oil that I put in until it is filled to the recommended level. From there I will remark the dipstick. I guess I have not been keeping the proper amount of oil in the engine since new.

I learned to take the yanny design with a grain of salt. If the captivity is suppose to be a certain amount, then so be it. Their design flaws were very puzzling durning the installation. See my blog.

It makes since that the dip stick markings are off with the motor tilted back. The oil capitity is what it is no matter what the stick reads. If the motor were level, as the manual says it's suppose to be, then the stick would read correctly. Would one read a cars stick if it were on a steep hill?

The only concern I see is if the crankshaft were to splash the oil. But that happens anyway with the boat/car being tossed around. In fact, in the old days, crank shafts had spoons that dipped into the oil and splashed around for lubrication.

With the stick tube being at the very rear of the oil pan the reading will change at any angle other the level. BUT, it makes it very good for pumping out all the old oil when the motor is tilted back.

[reprise]

Originally Posted by bytownboy

Should I just suck some oil out and quit being so anal?

IMHO, yes.

[delmarrey]

You do know that if a motor doesn't have enough oil that the remaining oil overheats and brakes down loosing its ability to lubricate.

And extra quart or two is not going to hurt a motor. Just think about the crank cases that get filled with diesel fuel and still run w/o damage.

[transmitterdan]

I believe too much oil can cause problems. If the crank splashes a lot of oil and gets it all foamed up then lubrication suffers. Therefore, I believe it is possible to over fill and cause excess wear.

I think the dipstick is the best gauge. If the engine is tilted less than the max specification then fill it to the mark. That's the only way you know the level is at the correct place for the oil pump to work.

Oil is also a coolant as well as lubricant. To little oil reduces its ability to maintain temperature.

Before reading the dipstick of a Yanmar first remove it, wipe, insert and remove. Then check the level against the mark.

[jhulmer]

I am currently rebuilding my 4JH2E.

I know that the oil cooler on the back of the engine may hold a small amount of oil during an oil change. In other words the initial oil fill would be 6.5 liters but it may only take 5 or 6 liters for an oil change. The oil heat exchanger on my engine also cools the KM4A gear which I'm sure does not drain back to the oil pan and that accounts for at least a liter.

I've been told not to worry about the level as long as I keep it at or just above the full mark on my 10deg inclined engine.

There is a drain plug on the oil pan opposite the dipstick tube and if accessible is a much better way to drain the oil and any sludge buildup.

The tilt of the engine as I have been told by installers is common on sailboats and Yanmar has installed the dipstick on the centerline in most later model engines to get a better average oil level reading.

[hpeer]

Is there anything definitive from Yanmar on the orientation of the dip stick and how to interpret the oil readings?

Somewhere I read the loop on the top of the stick should point forward. That makes the high/low marks come out facing you. Makes sense.

Has anyone here seen these instructions from Yamar?

........slight rant below......

FWIW, Yanmar instructions say to check oil before running engine. Oil check should be done 10 minutes after shutting down. Sounds like lawyer talk interpreted to mean "It's your fault."

[Russ]

Yes ou are correct. My Yanmar guy said same when he installed my engine. Very important.

[delmarrey]

Originally Posted by hpeer

Is there anything definitive from Yanmar on the orientation of the dip stick and how to interpret the oil readings?

Somewhere I read the loop on the top of the stick should point forward. That makes the high/low marks come out facing you. Makes sense.

Has anyone here seen these instructions from Yamar?

........slight rant below......

FWIW, Yanmar instructions say to check oil before running engine. Oil check should be done 10 minutes after shutting down. Sounds like lawyer talk interpreted to mean "It's your fault."

In order to meet EPA standards the crankcase is sealed. Note the rubber seal at the head of the dipstick. Yanmar gives 10 minutes for the oil to drain back down for a proper oil level and cool, maybe due to the way it drains.

There is a diaphragm valve in the rocker arm cover that needs to be maintained, which creates a vacuum when it cools. As long as the diaphragm is still working properly. It allows air to come in, but not out. The engine is supposed to recycle blow-by from the crankcase.

When you first pull the dipstick it allows air to enter the crankcase, which allows the oil it come up the tube. Then you can reinsert the dipstick to check the proper level.

As for which direction, it doesn't matter. Just read the highest side. It goes in at an angle, so the high side is the bottom side of the stick.

[hpeer]

Read the high side.

OK, gottcha. Thanks.

[SteveInMD]

Originally Posted by Hudson Force

I've developed the habit of removing the oil fill cap before checking my oil level. I found that, when I left the system closed, I would sometimes see unrealistic high and inconsistent levels on my dipstick. Pressure? Coincidence? Regardless, with the fill cap off I can always get the same reading when I check the oil twice in succession and not with the fill cap closed.

I do this too. I think there is often a little pressure in the motor after running which elevates the stick reading. The only other way I get a consistent reading is to leave it overnight, pull out the stick and read it immediately.