Finally I managed to fix the smoke coming from the engine cabine. After doing some investigation I have realised that smoke is coming from crankshaft valve for breathing.
Jumped to bunnings, got 5 m of pipe and managed to bring that smoke at the back of the boat.
Very happy now. I have realised that smoke is very heavy if engine is cold and as soon as engine gets hot smoke is reducing. Installed a plastic L at the end of the pipe so water can't come in.

Here are some photos.

Oil will collect at the lowest part of the hose, then you will have in effect blocked the breather, not an ideal situation pressure will be able to build in the crankcase and oil seals will be blown out, oil escapes and cease motor or a runaway might occur motor go bang ! May I suggest you put a collector at the lowest point and drain it regularly, but a rebuild is the only real fix

Worn rings increasing crankcase pressure. As others have stated, if you use your motor conservatively it'll give you continuing good service. If you push it, it'll fail one way or another.
Consider it from a Psych point of view. Your worn rings are past trauma. Keep stress levels within limits and things will go ok. Increase the stress, and past traumas will resurface and it'll all turn to s**t!
Treatments/therapies like Decarbonizer and good oil help, but you've also got other underlying issues such as worn valve guides, likely worn diesel pump and cam gear which need to be acknowledged.Push things unnecessarily and your patient (motor) will experience runaway (previously mentioned) or lose its bearings (literally) requiring a lengthy, costly admission to the mechanics hospital.

You will need an oil catch can in that pipe, preferably one with a sight tube on the side so you can keep an eye on the level. But mostly you need to forget trying to maintain hull speed under power. Use the engine to get on and off the mooring only and use moderate revs. Plan your day so you can sail the yacht everywhere in all wind strengths. In particular practice sailing on to your mooring using just the mainsail. Drop a temporary marker in a clear area and practice this skill, you will probably be needing it soon.

Thank you guys. But why would oil come out from the valve? If oil is on the level it shouldn't come out. My understanding is if you have to much oil than it will escape!
Anyway I will go gently on engine but it looks like decarbonising engine made it very quiet but also reduced the compression...

I will try to copy a plastic container that is collecting water out of exhoust just in case any oil comes out.

Thank you tigers.

The smoke you see is vaporised oil, like steam is to water, smoke will cool and turn into a very black oil that will become highly unpleasant if it is let loose on the bilge

OK,
Whent this morning to start the engine. No way, undone the belt that connects the alternator it fired like crazy. It looks like decarbonising engine actually killed it. As soon as revs are up I can shoot down the engine connect the alternator belt snd everything is smooth..

Spoke with my mechanic. He suggested to start the engine and let it idle it for 24h. That will make carbon to build a bit and will help to start the engine without removing the belt. However, he told me that engine must go a part get rebuild and that I can go my offshore sailing. Till then I can only dream about it.
This was a good lesson not to trust people. When I bought the boat I Bern told the engine was reconditioned a couple years a go and decarbonising will give an engine a bit more of a kick ( just what I need to be safe out there in the ocean). Well, carbon was actually holding engine together. I am glad that I know the truth and eventually will rebuild that engine and finally reach Japan one day!
Thank you guys for all your help I appreciate it.

The motors rooted, no surprise there, it still runs that's a winner. I don't hold any hope for a 24hr engine idle secession doing much good ( the premise being that an engine left to idle will not get to operating temp and unburnt fuel will build up on the form of carbon. Good luck ! ) your solar panel keeps the battery charged to start rooted motor, so ditch the alternator, it's just hogging engine power. Sail the boat it seems from all accounts the Tasman sail ok. Motor only when needed. And make your coffee with a little espresso on a camp stove or a plunger with hot water from a thermos. And check oil religiously, and have plenty in store. Good luck tiger

As soon as revs are up I can shoot down the engine connect the alternator belt snd everything is smooth..

Now that is a little trick that I would like to see.

gary

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Serb1980 said..
OK,
Whent this morning to start the engine. No way, undone the belt that connects the alternator it fired like crazy. It looks like decarbonising engine actually killed it. As soon as revs are up I can shoot down the engine connect the alternator belt snd everything is smooth..

Spoke with my mechanic. He suggested to start the engine and let it idle it for 24h. That will make carbon to build a bit and will help to start the engine without removing the belt. However, he told me that engine must go a part get rebuild and that I can go my offshore sailing. Till then I can only dream about it.
This was a good lesson not to trust people. When I bought the boat I Bern told the engine was reconditioned a couple years a go and decarbonising will give an engine a bit more of a kick ( just what I need to be safe out there in the ocean). Well, carbon was actually holding engine together. I am glad that I know the truth and eventually will rebuild that engine and finally reach Japan one day!
Thank you guys for all your help I appreciate it.

Have you considered installing a new diesel into your existing arrangement - so keep as much as you can of your existing drive train (as long as it is in a suitable condition for your trip to Japan) and replace the "rooted" diesel with a new diesel which would come with associated new engine mounts and coupling, probably more replacement components. For example Beta Diesel at Taren Point are experts at this, and their 10hp should suit fine but obviously needing to be confirmed as regards all aspects - these are marinised from a Kubota diesel which are top shelf. I have nothing to do with Beta or Kubota just trying to suggest a solution.

www.betadiesel.com.au/beta-10-beta-45t

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garymalmgren said..
As soon as revs are up I can shoot down the engine connect the alternator belt snd everything is smooth..

Now that is a little trick that I would like to see.

gary

Got my yanmar back! Yesterday added a bottle of honey like additive in the engine oil, let it run for 5 hours. This morning engine started as normal, went for a run and reached 6 knots on 75% of throttle. No smoke is coming from chsnkshaft breather...

Happy as...

Love this additives....20 bucks in repco!...

Select to expand quote

garymalmgren said..
As soon as revs are up I can shoot down the engine connect the alternator belt snd everything is smooth..

Now that is a little trick that I would like to see.

gary

I think a lot of us would like to see how you do this - "As soon as revs are up I can shoot down the engine connect the alternator belt"

Could you please take a video so we know how it's done - TYA!!

Select to expand quote

Lazzz said..

garymalmgren said..
As soon as revs are up I can shoot down the engine connect the alternator belt snd everything is smooth..

Now that is a little trick that I would like to see.

gary

I think a lot of us would like to see how you do this - "As soon as revs are up I can shoot down the engine connect the alternator belt"

Could you please take a video so we know how it's done - TYA!!

just like this Lazzzzzz

Not a lot to go bad there

Those that have spent years working with old agriculture equipment are usually experts at it.
I still have all my fingers too

A shearing shed I grew up around had some old massive probably only a couple of hp single cylinder motor that had a flat maybe 4" wide leather drive belt for the shearing gear. Start procedure was wind the crank handle till it fired and get out of the way of the handle till it dropped off, then take a broom handle an slide the belt on the the flat pulley. It was the highlight of the day drawing straws to see who got to start old methuselah. Thanks for reviving the memories id completely forgotten that caper

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Craig66 said..

just like this Lazzzzzz

Not a lot to go bad there

Mmmmm, seems simple enough!!

I might give it a try next service - might have a go at changing the impellor while I'm at it!!

Should be easy to change the oil as well - out the bottom & in at the top.

Fuel filters might be a problem though.

I have a mate with a finger missing - bet you can't guess how he lost it!! I was with him at the time - so much blood!!

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woko said..
A shearing shed I grew up around had some old massive probably only a couple of hp single cylinder motor that had a flat maybe 4" wide leather drive belt for the shearing gear. Start procedure was wind the crank handle till it fired and get out of the way of the handle till it dropped off, then take a broom handle an slide the belt on the the flat pulley. It was the highlight of the day drawing straws to see who got to start old methuselah. Thanks for reviving the memories id completely forgotten that caper

I found old down the hole bore pumps the worst. More than often they had long multiple V belts with a cross over twist , often you had no choice but to start the motor with the belts off because of the head pressure in the line. Pumps that where real difficult or super dangerous I would make an over centre belt tensioner to slip the belts along with fitting a valve at the head of the pump to relieve head pressure in the line..

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Lazzz said..

garymalmgren said..
As soon as revs are up I can shoot down the engine connect the alternator belt snd everything is smooth..

Now that is a little trick that I would like to see.

gary

I think a lot of us would like to see how you do this - "As soon as revs are up I can shoot down the engine connect the alternator belt"

Could you please take a video so we know how it's done - TYA!!

Ok, now engine is starting Ok and I really don't want to do this because it's very difficult to find the fine balance between perfectly tigh brlt and loose belt. If too loose it makes a lot of noise.
I will guide you step buy step and send the photo so you can understand how is done.

1 engine is to going slow revs when starts.
2. Then I unscrew the bolts (see the picture) and make my alterbator move to the left down for about 5 cm. Remove the belt.
3. Start the engine and let it come to the max revs. Let it rum for a min.
4.put the belt back and screw the bolts to fine tune the belt. (left screw adjusts how tight belt will be and the one in the middle just makes tight all alternator arm). Start the engine and rev it.

Luckily the honey like additive made seals expend a bit and compression is back so I don't need to play with belt any more.

Please see pictures. Hope it helps.

Select to expand quote

Serb1980 said..

Lazzz said..

garymalmgren said..
As soon as revs are up I can shoot down the engine connect the alternator belt snd everything is smooth..

Now that is a little trick that I would like to see.

gary

I think a lot of us would like to see how you do this - "As soon as revs are up I can shoot down the engine connect the alternator belt"

Could you please take a video so we know how it's done - TYA!!

Ok, now engine is starting Ok and I really don't want to do this because it's very difficult to find the fine balance between perfectly tigh brlt and loose belt. If too loose it makes a lot of noise.
I will guide you step buy step and send the photo so you can understand how is done.

1 engine is to going slow revs when starts.
2. Then I unscrew the bolts (see the picture) and make my alterbator move to the left down for about 5 cm. Remove the belt.
3. Start the engine and let it come to the max revs. Let it rum for a min.
4.put the belt back and screw the bolts to fine tune the belt. (left screw adjusts how tight belt will be and the one in the middle just makes tight all alternator arm). Start the engine and rev it.

Luckily the honey like additive made seals expend a bit and compression is back so I don't need to play with belt any more.

Please see pictures. Hope it helps.

Little update:
New rebuild engine ( yse8hp) with 5 years warranty is 5k.
So far the best results I got with penrite 30-70 stop burning oil and nulon stop smoke (see photo).

Decided to pull the engine out are restore it by my self and a friend of mine ( a diesel mechanic)...

Take care...