Yanmar 3GM30 running well but using a lot of oil.

[fred4936]

All good points that I will tuck in my mind, since I also have a 3GM30F. A friend of mine had a similar problem with his non Yanmar diesel. He had very high oil consumption, then found out he had a fuel injection problem; too much fuel being pumped in, washing the cylinder walls.

[a64pilot]

Originally Posted by Wotname

No intention to insult your intelligence but are you aware of the difficulties of accurately reading the dipstick on these Yanmar engines.

I have found the best way to run the engine, shut it down, wait ten minutes, remove the oil filler cap, remove and clean dipstick, refit dipstick and withdraw immediately to read oil level. This seems to give consistent readings but others may have their own special procedure.

If you have to remove the oil filler cap, that means you have a crankcase vent blockage.
I suspect you don’t though.
Many Marine engines dip stick tube goes all the way to the bottom of the pan, This puts it under the oil level, and since the top is sealed when the stick is installed heating or cooling of the air in the tube will make the oil level rise or fall.
So remove the stick and wipe it off, that lets the oil level be correct then reinsert the stick to measure.

An automobile you can remove the stick in the morning to get an accurate reading without doing the wipe it off and reinsert thing a marine engine y9u can’t usually.

If the Marine engines tube didn’t go all the way or real close to the bottom of the pan, then we would have a real hard time making sure the flimsy plastic tube we suck oil out of was at the bottom to get all the oil out.

[a64pilot]

On this motor I’d bet lunch the last overhaul left a corse cross hatching or maybe not done at a good angle, honing is an art if not done automatically, which in small shops is rare. Your looking for a 45 degree angle and that means aggressively pulling the hone up in and out and many don’t put that much work into it.
And God forbid if a dingleberry hone was used to roughen up the cylinder and or not bored, then it’s going to be hard to seat the rings, best bet is to run it hard for an extended period, by hard I mean near full max continuous power, often 100 or 200 RPM off the top for several hours.
Of course watch temps, cause if your cooling system is marginal, you’ll find out when it overheats.

If you run it easy too long, it will never seat the rings.

[a64pilot]

Read this, it’s about aircraft engines, but a piston engine, is pretty much a piston engine. It explains exactly why you need to run an engine hard, early in its life to seat rings.
Ignore the beginning about oils as we only use detergent oil, that is what ashless dispersant oil is.
https://www.lycoming.com/content/har...t-engine-break

[kmacdonald]

Ball hones (dingleberry) work great. They won't fix oval cylinder bores but they deglaze and put nice crosshatching on the bores. I don't know about using them on chromed aircraft cylinder bores though. Above about 10k hours you should put in new liners or rebore but at that point it might just be better getting a new engine. That's when ovaling becomes a problem (10k hours). Ball hone if less than about 8k hours and hope for another 4k hours. For $400 you can do a valve job, new gaskets, lift pump, rings, glow plugs, ball hone, rebuild injectors, and a few other odds and ends and have a reasonable chance at another 4k hours.

[kmacdonald]

Bad oil ring wont cause blowby. Bad compression ring will.

[Scubaseas]

I have to agree that dingeberries work fine as deglazers. If you need to cut a straight bore, especially these days where the sleeve can be way out from the pistons, sure then a torque plate and a good Sunnen is in order but dingles work fine. To dingle or not is kind of like anchor and guns on boats arguments here. To each his own.



I'd run it hard for about 20 hours or so. Keep an eye on the oil consumption and temps (more important you check oil level under the same conditions especially temperature, i.e. cold and with a couple hours drain back) and not worry about it much. If you really want to seat your rings fast and assume they didn't hone your liners you could, mind you I am not saying you should and I wouldn't but you could use the old red neck/plywood racer trick (hey may as well equally offend) of running at WOT and sprinkling a 1/2 cup of Bon Ami or Bartender's Friend down the intake. Cuts the glaze real quick. Not great for the bearings but it can get you and extra point something second off your straight track time.



Your issue may be as simple as they didn't deglaze the bores and the rings are not well seated. Or as bad as you need to redo the lower end. Oil's cheap.....

[VanIslandGuy]

John Deere makes a product called "break-in oil" that is supposed to be used in the initial hours of break of the engine. It can also be used for a 100 hour period to help with deglazing. My Yanmar mechanic recommends it highly when dealing with low time motors that haven't been broken in properly.

Before doing this though, it would be wise to do a compression test of each cylinder to see if one or more are below spec. Now you have a baseline to measure. Switch to the break-in oil and run it hard for 100 hours or one season, and change out the oil. After the oil change you can recheck your compression to see if it improved. If your are very desperate for fast deglazing, you can read about the "bon-ami" method through the air intake. I'm sure it works but I'm not brave enough to try it on my motor.

If it is an older Yanmar, make sure not to use synthetic oil, and if you can find simple SAE 30 HD, oil use that as normally that is what your manual recommends.

[Wotname]

Originally Posted by a64pilot

If you have to remove the oil filler cap, that means you have a crankcase vent blockage.
I suspect you don’t though.
......

Both statements are true of course!

I got into the habit of removing the oil filler cap decades ago probably well before I fully understood the mechanics of the marine oil dipstick! The habit has stuck and until your post, I haven't thought about again. While it does't hurt, maybe it is time to change my old habits!!

[kmacdonald]

Originally Posted by Scubaseas

I have to agree that dingeberries work fine as deglazers. If you need to cut a straight bore, especially these days where the sleeve can be way out from the pistons, sure then a torque plate and a good Sunnen is in order but dingles work fine. To dingle or not is kind of like anchor and guns on boats arguments here. To each his own.

Yep. Building high performance, blueprinted engines require the precision of a torque plate and Sunnen is the place to look. For the casual rebuilder the ball hones (Flex Hones) are adequate for a do-it-yourself engine refresh. A $400 refresh can buy a lot of hours for the DIY'er. A $100 valve job is usually all that's needed though if on a really tight budget.

[Compass790]

The other thing you can do to try to slow the oil consumption, AFTER, you've run it hard a few times is go to 20w-60 oil.
Personally I'd prefer to work out why it's using so much but if you want to do your 2 mth trip before getting in too deep, that might be a way to slow it a bit.
Bodes well if oil consumption has slowed after 1st hard run.
BTW our little Yanmar took about 50 hours to slow down on the oil consumption after fitting new rings in a worn bore.

[a64pilot]

Dingleberry hones are an abomination, pure junk, no self respecting mechanic would do such a thing. Even hones with proper stones but that have springs are not good, a hone properly used will both straighten a slightly out of square bore and maintain a perfectly straight bore.
The only exception is a “choked” bore, I’m not sure how they are done.

A dingleberry hone is the same as driving in screws with a hammer, using a pipe wrench or pliers on nuts and bolts, the list goes on.
May as well just sand blast the bore as use a dingleberry.

[a64pilot]

There are no differences between new and old Diesels that would keep you from running a synthetic, however unless maybe a turbo that you run hard, I don’t see the need for a synthetic.
Many think that they can extend oil change intervals if they use a synthetic and that is completely incorrect, we just don’t do anything with our little Diesels that are hard on oil, we only change it because it gets full of soot, no telling how long the oil would be good for with a good high quality high bypass oil filter.
If anything most of us don’t get the oil hot enough to cook off moisture as it is.

[kmacdonald]

Originally Posted by a64pilot

Dingleberry hones are an abomination, pure junk, no self respecting mechanic would do such a thing. Even hones with proper stones but that have springs are not good, a hone properly used will both straighten a slightly out of square bore and maintain a perfectly straight bore.
The only exception is a “choked” bore, I’m not sure how they are done.

A dingleberry hone is the same as driving in screws with a hammer, using a pipe wrench or pliers on nuts and bolts, the list goes on.
May as well just sand blast the bore as use a dingleberry.

Ya. I guess I get what I pay for. 3 or $400 refresh with ball hone only gets me about 4000 hours.

[sailah]

I've used dingleberry hones on John Deere tractor, motorcycles, landcruiser engine. Never had an issue and I've owned all these vehicles long enough to know if there was. Would not hesitate to use in my diesel if required. It's def a skill to hone it fast enough to get proper crosshatching.