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

Something big that require revs / centrifugal force is the prop, and one blade sticking will obviously cause balance issues. I actually wondered if you had a bucket wrapped on the prop. If it was a sh

The thing is with Camshaft, Cranks, Chains, Cogs etc etc and any other solid mechanical timed mechanisms, if they fail in anyway, the issue is not intermittent. They all cause major and even catastrop

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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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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