Yanmar Smoking and Making Oil

[gulfstar1]

Hi Terry,

Debbie and I feel so bad things aren't working out for you guys. The only bridge between Ortega and Green Cove Springs is the Buckmann bridge at 65'. I didn't realize you were that high above the water. It's about 20 nm from downtown Jax to G.C.springs and if you could just get there maybe Joel could break away long enough to get some tests done on the engine and maybe answer some questions.
We wish you all the best.

Regards
Richard and Debbie
S/V At Last

[delmarrey]

Has anyone considered the transmission????

Originally Posted by Tspringer

The shaft rotates easily by hand when the engine is not in gear. The prop operates as it should and is if anything underpitched.

Have you monitored the tranny to see if it gets hot while running. Depending on the type of tranny it could be a multiple of things with 4000 hours. e.g. A bearing trying to seize, clutch plates coming apart, gears out of alignment, cones locking together, water in the oil causing rust in the bearings, broken snap ring binding between gears or even a gear coming apart.

Stick a magnet down the inlet hole and see if you bring up any metal filings. If so, drain the oil and see whats in it. Smell the oil to see if it's burnt, that would be the first give away.

[Boracay]

I didn't see the injector pump on your suspects list. One of the small precise parts involved in adding fuel for the turbo or returning fuel may be broken. Have you costed a new or rebuilt one?

You're about 25% into a rebuild now. After the injector pump the only major cost items are hone/rings/maybe pistons and valves/valve guides/surface head and removal/replace costs(others may add to this list).

Maybe not a major jump at this stage, especially if you can find a rebuild shop that will test run the engine under load and give you a guarantee.

Have you pulled the fuel return line off the tank and checked that fuel is being returned?

[Chief Engineer]

TS has verified that fuel is rreturning to the tank.

Terry....how about running the boat at the dock and take one injector off line at a time by cracking the nut.....you will have no fuel going into that cylinder..check for change in smoke level...just trying to brainstorm here.

[Tspringer]

Chief.... doing that under heavy load and leaving the nut cracked long enough for the person watching the smoke to get a good read on a change, would not a fairly large amount of high pressure diesel fuel be spraying all over the place? I know I can hold a rag over it, but how large a rag and mess should I expect?

We are watching the weather very close, if the predicted wind direction change from south southwest to west happens late tomorrow morning as predicted we will leave on the first ebb around 1:30 pm and sail south. It will be a bit rough, but we should be able to sail all the way to Lake Worth and start hunting for a real mechanic in a warmer location on Friday.

I have given consideration that the injection pump could be the culprit. As could an exhaust blockage from a delaminated hose... or a bad head gasket..... or the wrong injectors..... or bad rings on one or more cylinders.... or something in the valve gear.....

There are really many things it could be and I could easily end up spending as much as a new engine costs and waste months attempting to track it down. I am really wrestling with what to do. If I can find someone who is REALLY good and can come to the boat then I will pursue this engine some more but otherwise its a repower.



Terry

[hellosailor]

Regardless of what else might be right or wrong, if the engine is "making oil" then the first priority is to enumerate every path where fuel can get sucked or dropped into the lube system, and find out which of those paths has failed.

Doesn't Yanmar have a troubleshooting chart in any shop manual that says "RISING OIL LEVEL" or "FUEL IN OIL" followed by a flowchart to step through the possible causes?

As long as the engine is "making oil" you've got a major problem, to be fixed before anything petty liking "tuning" or "smoke" is a concern. Any shop that needs help understanding that, is one to RUN AWAY FROM. Authorized, experienced, recommended, or not.

Leaking past rings, leaking from high pressure system, leaking past diaphragms...SOMEwhere there is a critical failure allowing fuel into the lube oil, and that needs to be job #1.

[Gene :^)]

Even if you give in and re-power, you will need to check the exhaust back pressure first unless you plan to replace the entire exhaust system.

Continuing the repairs to this motor makes sense because every new peripheral part you put on will still be used when you rebuild the engine block and head. You are just rebuilding the entire engine piece by piece.

I still stand by my last list of possibilities in order of likely hood:

1. Intake restriction (ruled out).
2. Damaged Turbo (ruled out).
--
3. Restricted Exhaust (I hope you will test this).
4. Bad Injectors (I hate to say it, but if all else fails we need to look again at the injectors. Maybe there was a mistake there.)
5. Injection Timing off (seems unlikely but was not checked).
6. Bad Injection pump (seems unlikely but possible).

It will be interesting to see and I might learn something here, but I doubt the compression is going to be any part of the problem. We already determined that it starts easy and idles smooth. Runs great at low speed. No missing or weak cylinder.

At higher RPM, poor sealing rings should become less of an issue because duration holding pressure is less.

Glazed cylinder walls or stuck rings would normally be grey smoke from burning oil.

[Gene :^)]

Oops... Try the last two again:

At higher RPM, poor sealing rings should become less of an issue because the duration that the rings are holding the pressure is less.

Glazed cylinder walls or stuck rings would normally be blue(ish) grey smoke from burning oil.

[sigmasailor]

Originally Posted by Tspringer

Chief.... doing that under heavy load and leaving the nut cracked long enough for the person watching the smoke to get a good read on a change, would not a fairly large amount of high pressure diesel fuel be spraying all over the place? I know I can hold a rag over it, but how large a rag and mess should I expect?

Terry

At 200 gram/hp hour you would get 200*75/60= 250 gram /minute or 62 gram (about 2 oz) per cilinder per minute. If you can do it in 20 seconds less than an once per cylinder. Messy but not impossible.

[Captain Bill]

This thread has convinced me of one thing: I'll be signing up for a diesel mechanics course.

[Navicula]

these kids pay to have there diesel make black smoke

[Tspringer]

I will crack the injector nuts under load and watch the smoke the next time we do some testing and see what the effect on the smoke is.

While I expect a fairly rough start to a passage south (seas 6ft) we are planning to head out today and sail to Lake Worth. I feel like any hope of getting any competent help in fixing this here in Jacksonville is gone. There just isn't anyone here capable and available who can track this down so we have to leave.

I am going to do another post asking but if anyone can refer a GOOD and REAL diesel mechanic in the Lake Worth area we are going to need one. By real I mean a true mechanic who can test and determine what is actually wrong with the engine and NOT just throw parts at it hoping one will stick.


Terry

[cantxsailor]

At the risk of entering the debate so late I'm going to dive in now.

I have a 31year old YSM8R which I know couldn't be more different from your engine.

However the symptoms are almost identical. Black soot in the exhaust flow and lack/loss of power. On my naturally aspirated engine I wasn't getting any rise in the oil level that I could see but the oil was, after a change, almost instantly black as night.

I built a compression tester by using an old disassembled injector(no guts) with a shrader valve threaded into the top. I used a Northern Tool cheapo diesel compression tester($49) and got an incredibly low 185psi. I checked it 3 times just in case I had screwed something up somewhere. As most diesels are supposed to run between 400 and 600 psi I knew this couldnt be good even if I was wrong by 100%.

I decided on a rebuild.

I replaced the cylinder sleeve, piston and rings, wrist pin and bushing, main bearings, valves, valve seats and guides. When I first pulled the head I checked for valve sealing by removing the rocker assy and closing the valves and pouring fuel down the intake and the exhaust ports. Fuel ran out around the exhaust valve but not the intake valve. I assumed(confirmed by the head rebuilder)that the exhaust valve and seat were burned.

I know my methods are a bit primative by they DID work and showed me where to look. The fact that paid mechanics($70+perhour) don't have proper tooling makes me think I'm in the wrong business.

My suspicion is you have an engine that has reached its best before date and is in need of rebuilding. I spent the $700 for parts and head rebuilder labour happily after finding out the cost of a new motor.

I had bought a used engine(YSM12R) for $875 that I was told (yup by an "expert") that it was exactly the same footprint and would bolt right. It wasn't even close and I ended up selling it to a guy from California. He is still using it.

Before plopping down such a huge amount for a new engine look around for a good used motor. Yours is not uncommon. I found the one I bought on Ebay. If not that then get it rebuilt. The amount these guys charge for installation is, IMHO, next door to thievery. I do all my own work. Not because I like to do it but because I'm to poor to afford to have someone else do it for me.

It has been my experience working around(not repairing) various diesels from big trucks and heavy equipment to large generators and small marine engines that unless stuff is hanging out the side and making scarey noises they are easily and fairly cheaply rebuilt and good for many more years of service.

I know this bad timing is making a much anticipated trip into a bit of a nightmare but take a few days off if you can and come back with a fresh mind.

Remember my story.

I spent 2 years building or rebuilding various bits of my small old boat only to have it tossed into a swampy hole by hurricane IKE less than 2 months ahead of my departure date for a planned 6mo cruise. I fixed the (3) nasty holes in her hull and put her back in the water(by hand, but with lots of help) and then brought her home for another year of fixing, including the much needed engine rebuild.

Had I gone on that cruise with the engine as it was I can picture my boat as yours is right now. Maybe this minor(although right now feels major) set back is for the better.

Hang in there, DON'T get discouraged or give up and you'll see, it'll all work out for the better..................m

[cantxsailor]

P.S. The little old engine now works as well as I could have hoped. Now all I have to do is save up my money again so I can go sailing.......m

[Tspringer]

News....

One of the Mechanics I had been discussing this all with here in Jacksonville stopped by the boat this morning as we were prepping for sea. We talked more about all the symptoms and everything that has been tried so far and then we fired her up intending to crack the injectors under load and watch the smoke.

Before we got to that point... with the engine running at 1,000 under NO load we pulled the breather line to see if we felt any blow-by or such exactly as I had done before. We did not feel anything.

THEN.... we removed the oil fill cap that is low down on the crankcase in front of the injection pump. Air poured out.... along with very fuel diluted oil. As we revved the engine.... the air increased and pulsed.

Clearly, there is blow-by on one or more cylinders. The fuel is definitely diluted and I am going to change the oil again before we head out.

So the engine is blowing fuel/air past the rings in one or more cylinders. Is this happening because the injection pump has something wrong with it and it is grossly overfueling thus causing fuel to wash past the rings causing the blow-by OR is a ring cracked or something else ring related causing low compression and thus the engine cannot burn all the fuel being fed to it thus the black smoke and problems.

Still need the compression test. I expect it to show low compression on a couple of cylinders at least. If however with the injectors off we can get the cylinders dried out we can try to get the compression back, if we succeed then I lean toward an injection pump issue. IF we cannot get the compression to come back then I would think it is a rings problem that will require the engine to be rebuilt or replaced.


Terry