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Clunks... What's going on here?


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22 hours ago, Aleana said:

Have you got a holding tank? Could it blocked? Maybe every 14.3 engine rotations it tries to clear a stubborn blockage and gets a blowback?

What a faecetious suggestion ... ;)

 

But a guest did manage to “flush so much she couldn’t flush any more...”

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I have a D1-20 SD , curiously the core engine is a Shibaura , they have a JV with Perkins https://tractors.fandom.com/wiki/Perkins_Shibaura_Engines.Volvo then buy from Perkins, go figure.

My money is that its combustion/fuel related, the problem being, there are many potential causes as suggested by all above.

I am working with an excellent diesel technician right now to resolve a stubborn fuel delivery problem on a 3 cyl Kubota, he works on the Cook St ferries when not on stand down.

I'm meeting him at 9am today to hopefully get the final fix in place, he is based in Papakura , PM me if you want his contact, I will  show him your video .

 

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I showed the video to the technician, he thought it was Diesel Knock , ie combustion related. There are several possible causes but he suggested to start by inspecting the timing gears for missing teeth.  

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BOI is correct.  It is simply not possible. Injector timing goes out by a tooth and the engine will run really ruff. Two teeth and it will come to a stop. It is really that precise.
Having just had the sound fixed in my computer, I had another listen. Firstly, it is not a sharp crack like detonation or something hitting something. It has a slightly longer duration than a sharp crack. Like either something rubbing as it hits or the escape of Gas under pressure.
interestingly, if you do a quick math calc. Lets say the engine is idling at 650RPM. 650 divided by 60 is 10.8 revs per second. So that rules out anything rotating directly from the engine. If we divide that by 2 which is the number of complete revolutions between each cylinder firing, we get 5.4 revs per second. So that rules out anything turning at Cam speed. But!!! if we now divide that by number of cylinders, we get one cylinder firing at 1.8 seconds. I would say at a guess, that is about the cycle rate of the noise. Anyone feel free to check my Maths as I can easily screw numbers up.
If I am correct, it still does not give me many clues that would not also cause other visual signs, like exhaust smoke. But noise sounding like fast escaping gas under pressure could point to a blown gasket on anything like say Head or Exhaust or Valve damage/failure and the air is blowing back. Although none of those make any sense for other reasons, it may start you off on a possible helpful path to explore.
 

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The clank happens 15 times in a whisker over 13 seconds - i did some calculations based on idle speed of 800rpm . that gave a clank near to exactly every 12 turns of the crank. we need to know what that engines idle speed is set at to be sure . Doc? . heres a good question though ... what would make an engine try to twist on its mounts the same direction as its rotation and also make a clank sound?  we need to have a barbeque in Brittany to find out...

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6 hours ago, jim s said:

The clank happens 15 times in a whisker over 13 seconds - i did some calculations based on idle speed of 800rpm . that gave a clank near to exactly every 12 turns of the crank. we need to know what that engines idle speed is set at to be sure . Doc? . heres a good question though ... what would make an engine try to twist on its mounts the same direction as its rotation and also make a clank sound?  we need to have a barbeque in Brittany to find out...

engine idle is 800 (more or less).

 

BBQ is ready...

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1 minute ago, Aleana said:

Trying to engage gear? Is it saildrive? Slipping clutch cones?

There's a dude popping down to the boat this week sometime to swap out a stanchion... might ask him to just have a little poke around...

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2 hours ago, DrWatson said:

There's a dude popping down to the boat this week sometime to swap out a stanchion... might ask him to just have a little poke around...

You could well be onto it with that. Especially if the stanchion is a leaker. Diesel meets water and all that...

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13 minutes ago, Aleana said:

You could well be onto it with that. Especially if the stanchion is a leaker. Diesel meets water and all that...

Yeah except they are unrelated incidents....

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18 hours ago, BOIGuy said:

I think you need another technician. 

That engines pretty clever if it can change its timing by jumping a tooth then jump back to perfect for a while. 

I'll check back with him, I'm probably misquoting, he found the issue on the Kubota. 

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I've been out of crew.org for the last week, (not sailing unfortunately) Logged in expecting volvo to have come up with an answer / solution while I was otherwise occupied. Please poke them with a stick Doc, the suspense, the suspense, ???

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On 17/08/2020 at 2:02 AM, John B said:

Any news?

Don't tell me, Volvo has seen the video and said gosh, that's serious, we'll get there with a van and 2 men to solve this problem immediately. 

Yep, that's pretty much exactly the situation at the moment, everything except for the two guys and the van thing...

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16 minutes ago, Fish said:

Should I mention about now, my new Beta purrs like a kitten, and I can always get hold of the agent when I need to?

Starting to like the idea of 1000Ah of 48V Li and a DC motor slapped on the top of the saildrive...

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An update!

Good afternoon,
 
Our agent Volvo Penta Service xxx xxxxxx has been on board your vessel
 
They made several checks and they made running the engine during 30 minutes
 
they have changed alternator belt which was too much tensionned.They have also drained a few lube oil in the saildrive because oil level was too high
 
Then they runned again the engine and trouble di not appear anymore
 
 
Nethertheless, what i suggest you is when you're back around our location is to contact Jet marine, and make a sea trial with them
 
like this, you'll have an engineer on board and if troubl appear again, he will know where to go throught
 
May you be ok with it?

Waiting for your feedback,
 
Regards,

 

To note: belt was adjusted but professional Volvo certified service tech at 38h

Sail drive oil level checked by same ... if he didn’t add any oil then there was too much at commissioning. 

 

No mention of the tech was able to replicate the issue...

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