New twist on Yanmar issue?

[Gr8tewhite]

Hello all. I have scoured this forum for my specific issue but did not have success. Some similar, but not identical.

I have a Yanmar 3GM30F. This thing starts immediately, even when cold, idles great and performs very well and does not overheat. Unfortunately, it’s going through way too much oil. Approximately 1 quart every 12 hours. I had the boat surveyed approximately 50 hours ago and the surveyor put the engine through its paces but did not find any issues.

I can tell you I have two areas of concern. Although there is no abundance of smoke, and no visible blue or black, I can periodically smell the odor of burned oil coming from the exhaust. I typically motor around 2,800 rpm when I notice this. It is possible it could be happening constantly and I am only aware of it as the wind shifts, but again, no excessive smoke.

Secondly, and here is where it gets interesting, when maneuvering at a speed just enough to maintain steerage and just prior to engaging the Kanzaki transmission into reverse, I will give it a 4 or 5 second pause prior to shifting. Once I engage reverse and elevate the RPM’s to anything above 2,000, I almost immediately notice an oil-slick coming from the stern.

Without making concrete assumptions, I’m guessing the oil is coming from the raw water exhaust? The transmission oil and level are just fine. The engine is original to the boat, a 1996 with approximately 1,600 hours. It is cooled via fresh water/raw water heat exchanger. Neither the oil nor the coolant show any signs of having intrusion from one another. From the other posts, I am leaning towards a ring job, but the fact that it runs, idles, and starts so well (even after a month of not starting) is what perplexes me. Burning a little oil I could live with, but ejecting what appears to be several ounces directly into the water way is unacceptable. Any ideas or suggestions, as always, are appreciated.

[Lowcountry]

My first guess was rings or bore scoring.

[Gr8tewhite]

That was the direction I was leaning also.

[captstu]

Over prop can cause this. If you can’t get max rated rpm at wide open throttle, you will have unburned fuel left.

Is your oil ok? Over propping can cause oil level to rise.

[Cheechako]

Hmmm, I wouldn't jump right to a ring job. IIRC, there is an oil passage near the cylinder in the block, if the head gasket is leaking there, it can be burning oil by pumping right into the cylinder. The other potential is a cracked piston land, which these have some issues with. Mine didnt smoke, but was a bit hard starting at times, but not real bad. Yes overpropping could do it but if you are making 2800 rpm that's not really the issue.

[Compass790]

Without having knowledge of your engine model it seems strange that it does not smoke if it was a ring problem as if it was making it's way into the combustion chambers one would think a quart every 12 hrs would make it smoke a fair bit. Also if rings were that worn it would be hard to start surely? I'd be trying to see if there is anyway the oil can get into the water injection tho I see you say there is no evidence of that. But as you know some of these engines had piston issues.
Maybe do a compression test to check anyway? Let us know what you find out

[Gr8tewhite]

I will have a compression check done and keep everyone posted. I am currently looking for a Yanmar certified tech in the Clearwater / Saint Petersburg area. Any recommendations would be appreciated.

[wsmurdoch]

This is from my wife's blog entry for March 22, 2010. https://irish-eyes-to-the-bahamas.blogspot.com/2010/

"In Vero Beach I noticed that our oil pressure gauge read no pressure (like almost 0) although the alarm had not yet sounded. I told Bill, and he shut the engine off and checked the oil. Although low, there was still oil in the engine. Whew. Bill looked back at his log and realized the engine had been using much more oil than usual since the last oil change. We hadn’t noticed any strange engine noises or clouds of exhaust, but we decided when we got to Miami we would go to the local Yanmar dealer, Anchor Marine, and have a mechanic look at the engine.

Bill called Anchor Marine while we were motoring through Miami. He talked to the Service Manager who asked if the engine started easily (yes), was it making funny noises (no), or emitting embarrassing clouds of smoke (no). His advice was to buy some oil and go to the Bahamas. No matter what might be wrong, the fix would be the same: overhaul or replace the engine. Since that would take a couple of weeks and $$$$, we decided to follow the guy’s advice. Also, Anchor Marine is a working boatyard in a pretty poor neighborhood on the Miami River and not the sort of place where you go on long quiet solitary walks. I could envision several weeks confined to my bunk staying out of the mechanic’s way while he worked making a greasy mess of my home. We bought 10 gallons of oil."

We actually burned 12 gallons of oil at a rate that reached 1 gallon per 7 hours before returning to North Carolina. That fall I pulled the engine, took it to Mack Boring in New Jersey, and they rebuilt it. They found the rings in the aft cylinder to be locked in their grooves by corrosion, perhaps from salt water entering the cylinder at some point. Our engine is a 3HM35F the high compression version of the 3GM.

Bill

[Gr8tewhite]

Thank you, Bill. I actually read her post during my search of the forum and prior to submitting my own. I was hoping that my issue of oil entering the water, specifically when shifting into reverse, would mirror somebody’s experience. Thank you for your response.

[bgallinger]

Originally Posted by Gr8tewhite

Hello all. I have scoured this forum for my specific issue but did not have success. Some similar, but not identical.

I have a Yanmar 3GM30F. This thing starts immediately, even when cold, idles great and performs very well and does not overheat. Unfortunately, it’s going through way too much oil. Approximately 1 quart every 12 hours. I had the boat surveyed approximately 50 hours ago and the surveyor put the engine through its paces but did not find any issues.

I can tell you I have two areas of concern. Although there is no abundance of smoke, and no visible blue or black, I can periodically smell the odor of burned oil coming from the exhaust. I typically motor around 2,800 rpm when I notice this. It is possible it could be happening constantly and I am only aware of it as the wind shifts, but again, no excessive smoke.

Secondly, and here is where it gets interesting, when maneuvering at a speed just enough to maintain steerage and just prior to engaging the Kanzaki transmission into reverse, I will give it a 4 or 5 second pause prior to shifting. Once I engage reverse and elevate the RPM’s to anything above 2,000, I almost immediately notice an oil-slick coming from the stern.

Without making concrete assumptions, I’m guessing the oil is coming from the raw water exhaust? The transmission oil and level are just fine. The engine is original to the boat, a 1996 with approximately 1,600 hours. It is cooled via fresh water/raw water heat exchanger. Neither the oil nor the coolant show any signs of having intrusion from one another. From the other posts, I am leaning towards a ring job, but the fact that it runs, idles, and starts so well (even after a month of not starting) is what perplexes me. Burning a little oil I could live with, but ejecting what appears to be several ounces directly into the water way is unacceptable. Any ideas or suggestions, as always, are appreciated.

I have the same engine (1998), and it runs the same as yours. For some years now, it burns about 3/4 oz. of oil over 8 hours. I typically run the engine at 2500RPM. I have had the engine checked (W.W. Williams, Savannah) but still no improvement. Borescope was ok and no smoke. One individual suggested I check the valve seals. I would love to solve the issue!

[a64pilot]

I say this over and over, but one more time won’t hurt.
If a Diesel starts easily, makes good power and doesn’t smoke up the Anchorage, oil consumption is of no real concern.
If your oil consumption has slowly over time increased then it may be just wear, however if it’s been a quick jump, then of course something has happened. If it was a sudden increase, then you need to find out why.

If it’s bore glazing, then you may be able to recover it, change to a good quality high detergent oil, add a significant quantity of either Marvel Mystery oil or Sea Foam, and go run the snot out of her.
I mean warm her up slowly, but then hold it wide open for a couple of hours.
Bore glazing is a chemical deposition of unburned fuel etc and it may be burned / cleaned off by high temps and high detergent oil.

If it’s a stuck ring, it may also be freed up by running hard, maybe.

One model of Yanmar is bad about breaking pistons, I’m not sure which model it is, but I believe one of its major symptoms of a broken piston is hard starting, plus that will show up in a compression test, as a broken or stuck ring should.

If a compression test didn’t show a bad cylinder, I’d go run her hard with the Sea Foam.
Of course keep an eye on oil pressure and if it drops considerably ( it shouldn’t) then back off running her hard.

Pulling the head will give you a real good look at cylinder wear, and if it’s one cylinder that is the problem, the one one piston top will be greasy with oil.

[danielamartindm]

I have Yanmar 3YM30's with just 1300 hours on them. A few months ago, one of them was casting a slick out the exhaust. In my case, the culprits were two fuel injectors that were so badly worn that they had to be replaced rather than re-built; but my problem wasn't RPM or gear dependent. Are you sure the slick that you're noticing is oil, and not diesel? The burning of oil could be a separate issue from exhaust slick.

[kmacdonald]

Oil cooler leaking oil?

[Cheechako]

Both my 3GM30 's burned no oil to speak of. In fact I thought diesels were supposed to burn oil, but the Yanmar's didnt which surprised me. It was probably the ONLY thing I liked about the Yanmar. If I got down a quart it was almost time to do an oil change. But one eventually cracked a piston and had to be rebuilt. Burning a quart in 7-8 hours is quite bad.

As far as noticing oil burning, it's not always that visible. Depending on where you are observing from.

[Compass790]

One more thing I forgot to say to check. Does yr engine have an air cleaner? If so check that it isn't clogged as that can cause high oil consumption. Simple test is simply remove it if it does have one.