Yanmar Problems

[Loredo]

Dockhead,
thinking about the intercooler being the culprit...
It is my understanding that the difference between your engine and mine is that mine does not have an intercooler. Yet, I still get the same smoke as you. Hmmmm, next time I'm on the boat I'll check the intake air to turbo path and see what I find.

I'm not saying that the intercooler isn't the culprit or at least part of the problem but since my engine has none....

[Dockhead]

Originally Posted by Loredo

Dockhead,
thinking about the intercooler being the culprit...
It is my understanding that the difference between your engine and mine is that mine does not have an intercooler. Yet, I still get the same smoke as you. Hmmmm, next time I'm on the boat I'll check the intake air to turbo path and see what I find.

I'm not saying that the intercooler isn't the culprit or at least part of the problem but since my engine has none....

I'm actually more concerned about the failure to reach full revs, than the smoke.

I'm kind of resigned to the smoke. The first year or two I owned this boat, the Yanmar smoked like a chimney (billows on startup) but ran like a top. I would be ok to get back to that situation -- if the smoke and revs problem turn out to be not related.

[Dockhead]

Last week, I motored (mostly) 150 miles in a dead calm from Hamble to Dunkerque near the border between Belgium and France.

My cutting out problem -- which I've had for probably 4 years by now and which has driven me crazy --- got worse, to the extent that I could hardly rev over 2000 RPM.

On a sudden impulse, I decided to heave-to and change the small fuel filter and bleed the fuel system. Voila!!! There was air in the fuel system!! The Yanmar now runs like a Swiss watch again -- incredibly smooth all the way up to 4000 RPM. Endless, seamless power with that gutsy flat torque curve which turbodiesels have. Problem completely eliminated.

So it seems that I must have a pinhole leak in the fuel system somewhere. I will work through the fuel system when I get to Finland; meanwhile I will just bleed the system if the problem reappears.


But how in the world could this have gotten by my diagnostic procedure??? I am feeling pretty sheepish (not to say, like a complete idiot ) to have wasted so much time and money on two different engineers, and even having taken the injection pump off for bench diagnosis. How could I have missed this? I eliminated it early on for some reason and for some reason never again tried bleeding the system.

Another data point in favor of Occam's Razor, or at least, the prevalence of simple problems.


I still have the smoke, which doesn't bother me all that much, but when I have time (probably in Finland) I will follow up on Dhillen's suggestion to clean out the intercooler. Meanwhile it is amazing how smooth and powerful the Yanmar is. It sings a sweet song, so much so, that I hardly mind motoring. Maybe Yanmars are not so bad after all. I might be falling in love with it again.

[Andrew Troup]

Kudos for having the guts to fess up and bare your soul, mate.

I'm sure many reading this will be well aware how easy it is to assume that something we "eliminated" some time ago is off the list of possible causes for good.

When in fact it can either happen that we only thought we'd eliminated it (as you seem to suspect), or occasionally in a long-drawn out problem solving process: that "prime" suspect, proven at the time not guilty, might later perversely develop, becoming an active participant in a multifactorial problem.

So that when we eliminate (by curing them) the other cause(s), it's the "last man standing".

Which reminds me of one of many things to dislike about multifactorial problems with nebulous symptoms: sometimes you don't realise you even had some of the lesser causes, so learning about them is not always available, even after exhaustive troubleshooting ...

I guess the other familiar syndrome is looking for some mislaid item, (as only a male can do), repeatedly thinking we were going back to all the places it SHOULD be, only to eventually find it in the first and most obvious place we had looked, and somehow ticked off for keeps !

[Andrew Troup]

One thing which strikes me reviewing the thread, although I hadn't noticed it: I wonder if it would've be better to have started two separate threads, one focussed on each problem?

With 20/20 hindsight, it's clear that the fuel starvation symptoms did not get nearly as much input as the smoking, and it's often the case that 'the rich get richer': the more one subtopic gets discussed, the more attention it receives.

???

[Dockhead]

Originally Posted by Andrew Troup

I guess the other familiar syndrome is looking for some mislaid item, (as only a male can do), repeatedly thinking we were going back to all the places it SHOULD be, only to eventually find it in the first and most obvious place we had looked, and somehow ticked off for keeps !

Indeed -- a perfect analogy

[Dhillen]

Dockhead,

Excellent news and thanks for sharing with us. It is also a good reminder to always try the easy stuff first - which I often forget to my cost.

Cheers.

Dhillen

[Kenomac]

Who would have thunk it?

It's difficult to imagine you heading up to Finland right now. Here in New Engalnd it's still cold, temps finally up from freezing only a week ago, now back down to cold today. Boats here are still on the hard.

Ken

[Dockhead]

Originally Posted by Kenomac

Who would have thunk it?

It's difficult to imagine you heading up to Finland right now. Here in New Engalnd it's still cold, temps finally up from freezing only a week ago, now back down to cold today. Boats here are still on the hard.

Ken

That's because you don't have the Gulf Stream. I've just been on Helgoland (fascinating place BTW), and there it rarely gets below 10C, although its at 54N.

[weavis]

Originally Posted by Dockhead

Last week, I motored (mostly) 150 miles in a dead calm from Hamble to Dunkerque near the border between Belgium and France.

My cutting out problem -- which I've had for probably 4 years by now and which has driven me crazy --- got worse, to the extent that I could hardly rev over 2000 RPM.

On a sudden impulse, I decided to heave-to and change the small fuel filter and bleed the fuel system. Voila!!! There was air in the fuel system!! The Yanmar now runs like a Swiss watch again -- incredibly smooth all the way up to 4000 RPM. Endless, seamless power with that gutsy flat torque curve which turbodiesels have. Problem completely eliminated.

So it seems that I must have a pinhole leak in the fuel system somewhere. I will work through the fuel system when I get to Finland; meanwhile I will just bleed the system if the problem reappears.


But how in the world could this have gotten by my diagnostic procedure??? I am feeling pretty sheepish (not to say, like a complete idiot ) to have wasted so much time and money on two different engineers, and even having taken the injection pump off for bench diagnosis. How could I have missed this? I eliminated it early on for some reason and for some reason never again tried bleeding the system.

Another data point in favor of Occam's Razor, or at least, the prevalence of simple problems.


I still have the smoke, which doesn't bother me all that much, but when I have time (probably in Finland) I will follow up on Dhillen's suggestion to clean out the intercooler. Meanwhile it is amazing how smooth and powerful the Yanmar is. It sings a sweet song, so much so, that I hardly mind motoring. Maybe Yanmars are not so bad after all. I might be falling in love with it again.

I am so sorry I didnt read this thread at all. I too had the same issues as Dockhead regarding cutting out. After a lot of money I took the boat to a old guy (in his early 70s) who was a diesel mechanic. He was not a boat engineer. He sat in the cockpit and listend to the engine, revved it up a bit and observed.

He started at the fuel tank, tightened connections up continuing to the filters, replaced them all, checked pipes and replaced one length, bled the system, and it fired up and ran beautifully. It took 2 hours. He charged me 60 quid plus cost of the pipe he changed, I already had the filters.

It was a lovely day, and I wanted to take the boat out and motor a bit just to enjoy it running. The old fellah asked me if he could come along as he had never been on yacht before and thought he would like to before he got too old LOL. Interesting man.

We motored for 2 hours and had a great chat. We shared some coffee with rum, or in his case, coffee flavoured rum...

So the bottom line, and as he reinforced. "Diesels are diesels, You need someone who knows diesels. Its an engine. Dont need to be a boat mechanic to work on diesels. you just need to know diesels".

[weavis]

Regarding grey smoke.

In my experience, and consequently every remedy that worked for me, it has been one of a couple of things.

Incorrect fuel injection timing or Low cylinder compression.

I de carboned my engine with OTC products which helped a couple of times on different engines, and once had my fuel injectors looked at and something done to them. Bottom line its unburned fuel smoking out the exhaust.
I would hesitatingly suggest that Yanmar have a design quirk on their injector timing. I think MORE yanmars smoke than not.

1. When grey/white occurs at cold start and then disappears as the engine warms up, the most common causes are fouling deposits around piston rings and/or cylinder glazing.
2. Continuous evidence of grey/white indicates a mechanical defect, or incorrect fuel timing.

[ontherocks83]

Dockhead now that you know what caused one of your problems do you think it would be worth while to install a vacuum gauge between your fuel filter and your fuel pump. I know durachoice makes one but there are lots to choose from Vacuum Gauges made specifically for applications involving Vacuum or negative pressure. . I know hindsight is what it is but possibly if you had one installed you would have checked it while the engine was running or struggling and seen that you were drawing a vacuum which would have keyed you in to a restriction issue. Under normal operation there should be 0 vacuum. Just a little food for thought. They are pretty simple to install, not expensive, and could have saved you a lot of frustration.

P.S. I am glad you found your problem and thank you very much for sharing. I love reading this kind of info as it is something else for me to put in my "tool box"

[Dockhead]

Originally Posted by ontherocks83

Dockhead now that you know what caused one of your problems do you think it would be worth while to install a vacuum gauge between your fuel filter and your fuel pump. I know durachoice makes one but there are lots to choose from Vacuum Gauges made specifically for applications involving Vacuum or negative pressure. . I know hindsight is what it is but possibly if you had one installed you would have checked it while the engine was running or struggling and seen that you were drawing a vacuum which would have keyed you in to a restriction issue. Under normal operation there should be 0 vacuum. Just a little food for thought. They are pretty simple to install, not expensive, and could have saved you a lot of frustration.

P.S. I am glad you found your problem and thank you very much for sharing. I love reading this kind of info as it is something else for me to put in my "tool box"

I have a vacuum gauge and check it regularly. There was no obstruction - there was air in the system, which the vacuum gauge doesn't detect.

[goboatingnow]

Dockhead, are you running on Gas oil or DERV. ( red or white diesel )

Dave


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[model 10]

Originally Posted by Dockhead

.
I have not, by the way, figured out how to adjust valve clearances on this engine. There's nothing about it in the service manual. I've done it a thousand times on petrol engines, but never on a diesel. I am a little daunted by the question of how to turn the engine to TDC (no spark plugs to pull out to relieve compression!) and how to find TDC. Anybody have any hints about how to do this?

Sure, with the rocker cover off, turn the engine in the normal direction until the intake valve has closed, another 30-40 deg and that should be about it. There is quite a bit of duration where both valves are completely closed and the lifters are on the heel of the cam lobe. The exh does not open for quite some time after tdc. As you probably know, you can feel tdc with the wrench you use to turn it. To make it easier, smack it with a rubber hammer or wait for the pressure to leak out.
It probably has hyd lifters so no spec is given.