Yanmar 4JH oil change puzzle

[SailorHarry]

If your engine is not parallel with the waterline (and most engines are inclined aft (aft end lower than forward end), then your dipstick oil level is not going to match what the manual says.

When we re-engined our Corbin 39 with a new Yanmar 4JH2E I simply added the proper amount of oil and remarked the dipstick accordingly. We sold the boat in 2013 with over six thousand trouble-free hours on the meter, so I guess I was right. Try it.

[a64pilot]

Originally Posted by SteveInMD

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.

Cap doesn't have anything to do with it, cause it has a crankcase vent. This happens with all Marine engines, reason is since the dip stick has a seal at the top, and they all should, since the dip stick tube exits at the bottom of the pan you have a sealed airspace in the tube, as the tube cools it will form a vacuum and draw oil up the tube, giving a false reading.
Once everything cools off to the same temp, the reading should be close, but best to wipe the stick reinsert and check then, that way you have broken the vacuum and allowed the oil level to drop in the tube.

[a64pilot]

An automobile does not do this as the dipstick tube does not go all the way to the bottom of the pan, since the dips stick tube isn't used for oil changes

[delmarrey]

Originally Posted by SailorHarry

When we re-engined our Corbin 39 with a new Yanmar 4JH2E I simply added the proper amount of oil and remarked the dipstick accordingly. We sold the boat in 2013 with over six thousand trouble-free hours on the meter, so I guess I was right. Try it.

Ditto! Did the same but rounded it off to an even quart.
And ditto on the last two posts.

[Dockhead]

Originally Posted by a64pilot

An automobile does not do this as the dipstick tube does not go all the way to the bottom of the pan, since the dips stick tube isn't used for oil changes

Thanks for this tidbit -- solved a mystery!!

[SobeFlyer]

I know this is an old thread, but my engine is new to me. Thank you all for insight. I offer a little in exchange. I recently removed my injection pump for servicing, and in addition to the oil that may be trapped in the oil cooler I can attest to a fair amount of trapped oil in the bottom of the fuel injector pump for lubricating the timing cam shaft. I'd estimate a little over a pint. FWIW, when I remove old oil, I put it in an old empty oil jug and make note of the quantity removed, then add the same quantity of new oil. This puts the level precisely back where you had it despite any trapped oil. The total quantity in the manual would be how much added to a new dry engine. Now that I think about it, the injector pump has a separate oil cap on it. I guess you could suck some out of there and replace the same quantity with new to, thus increasing the percentage of oil changed...

[delmarrey]

Just go by what it was on the dip stick. *Remember to wait 10 minutes after motor shut down to check dipstick. Also, check it twice, with the second dip being the most accurate. The dipstick tube is air tight, or should be.

A lot of oil drains back into the pan from all the passageways and valley’s.

Hopefully you recorded what the dipstick said before starting the work. It all depends on the angle of the motor, which according to the installation manual should not be more then 15º.

Mine was 17º so I had to specially mark my dip stick after the first initial fill. The main thing is that the deep part of the pan is full up to the shallow part of the pan. The base of the dipstick is mounted below the oil-line.

[delmarrey]

FYI - if you ever start getting diesel fuel in your oil pan, check the prime pump diaphragm. It’s good to carry a spare diaphragm.

[Dockhead]

Originally Posted by delmarrey

Just go by what it was on the dip stick. *Remember to wait 10 minutes after motor shut down to check dipstick. Also, check it twice, with the second dip being the most accurate. The dipstick tube is air tight, or should be. . . .

Maybe this varies by model, but the manual for my 4JH3 HTE says to check the oil immeditely after shut down, and do not check it without running the engine a little first.


This makes sense if you think about it -- you care about the crankcase level when the engine is running, and when it is running, there will be oil in the upper parts which hasn't drained down. Checkoing oil after everything has drained down will not reflect the level when the engine is running.

[delmarrey]

Sorry Dockhead, hate to burst your bubble but this has been posted before. This tag comes on a brand new motor......

[jtsailjt]

Originally Posted by delmarrey

Sorry Dockhead, hate to burst your bubble but this has been posted before. This tag comes on a brand new motor......

I don’t think anyone is bursting anyone’s bubble. I trust that you are both more than capable of reading your own owners manual and are doing what’s right for your particular engine.

I don’t see where either method, waiting 10 minutes or doing it right away, is inherently better. All it means is the dipstick has to be calibrated differently. Both methods can give you the same information as long as your dipstick is calibrated for the method you’re using.

I wonder if the 2 methods mentioned might have to do with the model year or possibly turbo vs normally aspirated or different type of injector pump?

[hpeer]

Not much point bickering between ourselves here.

Clearly different folks are getting different results form the processes.

For ME before, right after or 10 minutes matters little.

However I MUST remove the dip stick and wait for 15 seconds or so and repeat between dips. Only then can I get reliably repeatable results.

What I would like to see is a Yanmar rep get on here and provide some approved direction in this manner.

I would also like to know what the oil fill limits are; too much to too little. a cul, a pint, a quart, a half gallon?

And how does that relate to running on heal? I recall an admonition to not run with more that 17° of heal.

Baring input from Yanmar I would like to hear from some real full time rebuilders, guys who get these things trashed and rebuild them. What are there recommendations?

BTW: I think a lot of the problem is the dip stick enters the pan damn near flat. Very little vertical. Or so it is on my 4JH4. So a small change in oil level, or heal, has a disproportionate change in the oil level.