Yanmar 3GM30F engine, burning oil--Why? Can you help?

[ewsponberg]

Hi Everyone,
You have helped me generously before, and I'd like some help solving the following problem. Our boat, Corroboree, is 30 years old with its original Yanmar 3GM30F engine (SN: 560). When we bought the boat two years ago, the engine surveyor estimated that there was about 3,000 hours on it. We have added 160 hours to that since launching.

The problem is, this engine burns a lot of oil, about one quart every 16-20 hours. It should not burn oil at all. There are no oil leaks in the engine, the bilge is perfectly dry. The engine is a little hard to start when cold, and there is some blueish white smoke on starting, but that quickly dissipates. Once warm, the engine starts fine. The engine runs fine, too--smooth, with no excess noise or vibration. To handle this situation, we carry a lot of spare oil on board, and we monitor oil consumption religiously. A number of Yanmar mechanics have said we are facing an engine overhaul in the near future, so we are saving our dollars for that.

But my first question, for you mechanics, is what is causing the oil consumption? The various mechanics suggest either valve seals are leaking and have to be replaced. OR, the piston rings are worn and have to be replaced. Any thoughts? Are there any simple tests that I or a mechanic can do to would precisely pin down the cause so that we can determine a method of repair? I'd like to know more about the possible symptoms before going through exploratory surgery to tear the engine down in order to find out what's wrong.

The second question is about where to do this work. We are currently in the Dominican Republic at Ocean World Marina near Puerto Plata. Local sailors suggest cobbling together a repair plan and doing the engine repairs here. Getting parts into here is hard because of customs and importation red tape. Others suggest having the work done in Puerto Rico, including the Yanmar dealer in San Juan, but if you know anything about sailing against the Northeast Trade Winds, from here that is nearly impossible. We can get to the south side of Puerto Rico without much trouble, but getting direct to San Juan is not really in the cards. So, question: Can you suggest any mechanic or engine repair firm in Puerto Rico, or the DR, that you would trust to do a good job on scoping out the problem and getting our engine fixed?

Thanks for all your help in the past, it is most appreciated.

Cheers,

Eric

[a64pilot]

Valve seals cause a lot of smoke at start up, but very little consumption.
You have almost certainly have either worn rings, or glazed / polished cylinder walls, or maybe a cracked piston.
Glazed cylinder walls can sometimes be helped by running the snot out of it, however if it's worn maybe running the snot out of it is not a good idea.
I'd live with it until such time that it got hard to start or was smoking up the anchorage and then overhaul.
A compression check should determine if you have a cracked piston, and should give you a decent idea as to overall health.

[Bill O]

Eric,
Glad to see you made it off the dock,but not good news about your motor.

Looking around at others w/Yanmars that had large volume of oil consumption they consistently had bad rings/oil rings (from stuck/cracking/previous saltwater leaks into the cylinder). Apparently they can run on 2 cylinders but hard to start and don't always exhibit a lot of blue smoke while running.

Would agree the first step (if you haven't done it already) is to get a compression check to see if there are any issues. Did they do one with the motor survey for comparison?

If you don't want to head down to San Juan yet, it appears there are several Yanmar parts distributors in Santo Domingo (~115 mi each way).

Good luck,
(M Go Blue!)
Bill O.

[a64pilot]

Read this thread, it may help

http://www.cruisersforum.com/forums/...ar-107705.html

[ewsponberg]

Originally Posted by a64pilot

Read this thread, it may help

http://www.cruisersforum.com/forums/...ar-107705.html

Hi a64pilot, Thanks for the advice and the link to the other thread. Very interesting. I think my next step is to get a good mechanic to dig a little deeper with testing and inspection of the engine, and take it from there. Am in contact with a major diesel house in Santo Domingo for further advice.

I'll report back what progress we have made.

Any suggestions, anyone, on mechanics in Puerto Rico?

Cheers,

Eric

[ewsponberg]

Originally Posted by Bill O

Eric,
Glad to see you made it off the dock,but not good news about your motor.

Looking around at others w/Yanmars that had large volume of oil consumption they consistently had bad rings/oil rings (from stuck/cracking/previous saltwater leaks into the cylinder). Apparently they can run on 2 cylinders but hard to start and don't always exhibit a lot of blue smoke while running.

Would agree the first step (if you haven't done it already) is to get a compression check to see if there are any issues. Did they do one with the motor survey for comparison?

If you don't want to head down to San Juan yet, it appears there are several Yanmar parts distributors in Santo Domingo (~115 mi each way).

Good luck,
(M Go Blue!)
Bill O.

Hi Bill,

Thanks for the note. Glad I am not the only one having this problem. It seems to confirm pointing toward valve seals and/or piston rings. Am now in contact with diesel house in Santo Domingo for additional advice. Will report back when I know more.

Eric

[Diesel Bill]

I agree with A64pilot, Oil consumption 99% of the time is worn rings, worn cylinders/liners or worn loose valve guides and or valve guide seals. One other cause come to mind although it's a long shot. Dirty or partially blocked air intake strainer/filter. I came across a Waukeshaw 16 cylinder VHP that was burning excess oil. It was pulling oil past the rings due to dirt packed air filter. Hope you can repair it, but oil is cheap compared to a rebuild.

[a64pilot]

I think a compression test will tell a lot,

[sailorchic34]

High oil consumption and hard starting together probably means rings. If it was worn valve guides it would not be hard starting and oil consumption would not be so high. Though blue smoke in the exhust would be a sign of leaking valve guides.

From personal experience a 3gm30f can burn a quart of engine oil every 15 hours and not hardly smoke.

With the engine ideling, pull each decompression lever one at a time for a second and reset close. If one cylinder sounds different, then that is the cylinder with low compression.

Also try starting the engine when cold with the decompression lever of one cylinder that sounded different pulled. If the engine starts easier then you have a piston ring issue. Luckily that's only a $1200 repair if you do the work your self or $5k-$10k if someone else does it. Lots of labor, but not so hard if you can turn a wrench.

I would not expect a yanmar with 3000 hours to have low compression across all cylinders. They are long wearing. If your lucky it's just engine glazing, but that is rare in a fresh water cooled engine.

[ewsponberg]

Originally Posted by sailorchic34

High oil consumption and hard starting together probably means rings. If it was worn valve guides it would not be hard starting and oil consumption would not be so high. Though blue smoke in the exhust would be a sign of leaking valve guides.

From personal experience a 3gm30f can burn a quart of engine oil every 15 hours and not hardly smoke.

With the engine ideling, pull each decompression lever one at a time for a second and reset close. If one cylinder sounds different, then that is the cylinder with low compression.

Also try starting the engine when cold with the decompression lever of one cylinder that sounded different pulled. If the engine starts easier then you have a piston ring issue. Luckily that's only a $1200 repair if you do the work your self or $5k-$10k if someone else does it. Lots of labor, but not so hard if you can turn a wrench.

I would not expect a yanmar with 3000 hours to have low compression across all cylinders. They are long wearing. If your lucky it's just engine glazing, but that is rare in a fresh water cooled engine.

Hi Sailorchick34,
Thanks for your advice. I read the thread you started on a similar issue, and that gave me some insights. I'll try the tests you suggest and see what happens. While I am a retired naval architect and have some technical acumen, I am on a round-the-world cruise without access to any shop, nor the complete tools I would need to pull the engine apart and put it back together. I must rely on a qualified mechanic to do the job properly. I am taking this one step at a time, doing more tests for now, then decide where to go for repairs.

Has anyone had major engine work done in Puerto Rico? Can you recommend a good diesel engine house?

Diesel Bill, thanks for the advice. I think the air filter is pretty clear, always has been, so I don't think that's an issue.

Roger that, 64pilot, a compression test is a must before doing anything.

Will report back when I know more.

Eric

[DeepFrz]

Good luck Eric. I've admired your designs and enjoyed your articles.

[Diesel Bill]

My oil burner was bigger and burned more oil than your's. Just kidding. I was on an unrep oil tanker (underway replenishment) coming back from an I.O. (Indian Ocean) deployment after 106 days at sea. Ship was USNS Hassayampa.
We were en route to Subic Bay P.I. and off the bottom horn of India. The guys in the E/R were thinking of cold beer and girls (damn sailors) and weren't watching the water level sight glasses on the boilers. We lost 2 large down comer tubes in the port boiler and feed water was dumping into the furnace. Stb. boiler was not getting feed water as all was going to lowest pressure which was port boiler furnace.
Bear with me, I'm getting to the point of this yarn in a moment. We were dead in the water with one boiler with flooded furnace and collapsed fire brick and other boiler dry fired with resulting sagged/sagging tubes. We had an old EMD 645 inline 8 cylinder gen set up in the bow of the ship. This worn out old relic would burn through 5 gals of lube oil in 4 hours. We only had a few drums of diesel oil on board so when the last of it was gone we started feeding it turbine oil as we had over a 1,000 gals of that on board. I took us over a week to do repairs and plug tubes to limp into Singapore. I wish that I had pictures of the smoke screen. The bow of the ship was invisible in the smoke for over a week.
By the way the EMD 645 is a 2 stroke just like a Detroit 6-71 on steroids.

[Matsubob]

As long as the oil consumption is at a minimum, probably adding oil is the best approach. But to have to keep checking the oil level and not knowing if it is low or not would become a real pain.
My Yanmar 3GMF sits high enough in its beds to reach the pan bolts, although the rearmost four are a strain to reach. I can, and have, pulled the pan and head with the engine in place, allowing the removal of all three pistons. Pulling the head is pretty straightforward; you just remove whatever is in the way until you are down to the headbolts. If you keep everything catalogued for where it all came out of, you can put it all back, just as it was (always the best for engines).
I have the official Yanmar Shop Manual, purchased online in PDF format. This is invaluable!
I just finished helping a friend do the same thing to his, but we had to unhook his engine and raise it with a block and tackle a foot or two, in order to reach the pan bolts. It is totally doable!
While in there, I would replace the rod inserts, rings, wrist pin bushings, valve seals, and head gasket, of course. I would hone the cylinder liners to "rough them up a bit" to enhance the rings' seating. Assuming the main bearings are OK, I would leave them alone. The 3GM has a forward main bearing that must be removed by drill press, so that means shelling the block in order to take it to a machine shop. The rear seal is also press fit, but can be removed from the block and easily carried to a shop. Doing the mains would definitely mean a total teardown, but if you can avoid doing that, doing the aforementioned rings, rod inserts, wrist pins, valve seals is not a hard job at ALL!
You will only need 1/2" 17mm deep socket, for the head bolts, and the rest can be done with 3/8" drive sockets, mostly 12mm and 13mm. Of course, a torque wrench is invaluable when clamping the head back down! And it would be easier if it is a 1/2" drive one. A set of feeler guages for measuring ring gap and a valve compressor and valve lapper and cylinder hone would also be helpful. But the rest of the engine doesn't even need to be touched, so very straightforward!

[Kita]

Yep as said, rings or piston or something there,it's a compression issue, 99% sure just from the description, hard start early morning then start easier later,oil consumption ,,classic symptoms...is it possible with the hours you are saying that there is a heat exchanger issue that allowed water to get in the combustion chamber from the exhaust system and then that water is the beginning of the end really, ,,washes out the oil in the cylinder creates excessive wear and cracked Pistons? ...be a shame to fix the engine & then find out later you need to get that after it hurts the new one. ........point is unless you have the skills to build an engine,save the money, baby this one along & when you can just replace it as a unit...I know,I know,money,,, would you rather spend more & do it twice & risk losing the engine later cause we all know it's going to die when you really need it! No it's safer for everybody to just milk this one that you have a long as long as you can and save your money until you can afford to just replace it. Almost anybody can remove and replace that as a unit but it takes a skilled technician to do one of those Motors. But sometimes and I do mean sometimes you might get lucky and get away with doing that motor yourself. It really just depends upon how handy you are and if you have the tools. It's not that complicated of a process but if you don't know Motors I would recommend just remove and replace it as a unit cry about it for a while and then get over it move on

[Ken Z]

sounds like rings , possible one broke and scoured the wall or liner, some scours can be deep, could be valve guides, but i would lean toward ring. if a low ring a compression test might not be totally reliable on a reading. happened to me then the rest of the ring came off and really scoured the cylinder, it still ran, had to rebore .40 . piston ring can run $450. time for a good diesel mechanic, beating into the trades is a drag. best of luck.