Clunks... What's going on here?

[jim s 17]

the engine jumps clockwise with each clank - the inertia of the crank is clockwise, if something like the injector was faulty and fired a cylinder way too early then it would exactly do exactly as we are seeing and hearing. I have seen the same thing on a petrol engine when the electronic ignition unit was being overwhelmed by a failing voltage regulator. I could easily be wrong and i've never had a volvo injector apart but it is a possibilty... 

[wheels 374]

It isn't anything to do with the engine. Forget Injectors or timing. If the exhaust is clean, then there are no firing problems. Simple as that. Anything mechanically wrong with the engine that could cause this would only make the engine run worse and likely the noise would become much faster and louder when you up the RPM.
What I recommend you check is firstly that the gearbox Oil is at the correct level. If low, it could be a clutch cone grabbing maybe.
Secondly, check that the Gear cable is properly adjusted to sit in neutral. Not just about trying to engage. The engine is being moved on the mounts by an external force. A miss will cause a very different and only slight rocking motion.
One other thing it could be is the dampner plate that couples engine to Gearbox. But that means splitting the two apart and that is not easy. There are springs on this plate that can break. They stop "Injector Shock" from being transmitted to the gearbox. Not sure how a failure would cause this at idle, but it is the only thing I can think of that does fail. At 60hrs though, it should not have failed.
I would also send that Vid on to the mechanic.

[John B 89]

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 shaft, something caught on it. But you're saildrive. 

I know you're in selected neutral but I wonder if your Morse control or cables needs adjustment and the gearbox is actually engaged or part anyway. So I would start at looking at the prop when it's doing it, disconnect the cables and check the gear select position and after that if that says nothing, start thinking about gearbox to damper plate, as said above.

[Fogg 177]

Have you watched how the engine behaves when you shift from neutral into gear? Does it look & sound the same?

My previous sail-drive set-up used to jump incredibly every time I engaged gear,

As the others suggest, it does almost look like the engine is trying to jump into gear itself causing the clunk?

[Steve Pope 103]

Could there be a problem with the engine drive plate?? I've no idea what brand Volvo use, but it is probably bought in. Otherwise I would look at cam shaft, or even crank shaft, (Broken but still rotating) it seems about 1/2 speed which would fit in with the video, which gives more credence to the camshaft.

[wheels 374]

On 4/08/2020 at 4:56 PM, Steve Pope said:

Could there be a problem with the engine drive plate?? I've no idea what brand Volvo use, but it is probably bought in. Otherwise I would look at cam shaft, or even crank shaft, (Broken but still rotating) it seems about 1/2 speed which would fit in with the video, which gives more credence to the camshaft.

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 catastrophic failures that would abruptly bring the engine to a halt. Or at best, the ignition of the Fuel would be compromised and result in a smoky cylinder or two or more. From my own experience, here are a list of things I found over the years. Maybe it might help someone one day.

Broken lug on Camshaft = ruff running through out rev range. Smoking engine. Continual clacking noise that increases freq with revs.
Broken Cam shaft = Engine failed to start.
Blown Turbo= Engine was running at time, came to a halt with lots of black smoke. When turned over, sounds like it is trying to start, but doesn't and belching lots of smoke.
Broken bolt on Big End Bearing = Engine running OK at idle with slight knock sound. Sound becomes very loud and ruff as Revs increased. Eventual complete failure with Piston Rod punching through the block.
Injector pump timing issues = Engine fails to start.
Cam shaft timing issue due to sprocket/gear losing a tooth. Engine runs ruff and fails to start again.
Cambelt failure = Catastrophic failure of engine with lots of damage.
Many various reasons for loss of oil pressure = all resulting in Engine losing revs and completely locking up in a very short time.
Loss of coolant = For Cast iron blocks and heads, Engine losing revs and eventually locking up. After cooling down, engine starts and runs OK again and no apparently problems. May not always end up with such a good outcome.
Small amount of Water in Cylinder = Engine came to stop and failed to start again.
Large amount of water in Cylinder = Engine locked up hard on start. For smaller engines, no damage. For larger engine, one had bent Con Rod and one had cracked the Block although engine was running hard at time of taking a gulp.
Broken spring/s in drive plate = Noisy/rattly sound at idle. One had no drive at all.

That is all I can think of at the mo. I may think of others later.
 

[chariot 131]

I have a D1-30 that was fitted about 3 yrs ago. Was fitted with correct mounts but used to jump allm over the place. The engine mouints were soft mounts which i believe they use on the sail drive instalations. Being shaft drive it used to knock like hell at idle due to engine movement.

Had the mounts changed to hard mounts and problem solved.

The noise from your instalation is totally different to what I had but could be food for thought.

 

[Fogg 177]

DrW — did you send video to Volvo for their assessment?

[DrWatson 222]

On 4/08/2020 at 4:12 AM, Aleana said:

Have you watched how the engine behaves when you shift from neutral into gear? Does it look & sound the same?

My previous sail-drive set-up used to jump incredibly every time I engaged gear,

As the others suggest, it does almost look like the engine is trying to jump into gear itself causing the clunk?

I think this is a plausibility. Vid was sent to Volvo immediately. And to some other relevant parties incl. original mechanic (so he can see the issue that we were trying to replicate). Pogo Structures have also jumped in on their own initiative on our behalf and written to Volvo France head office to encourage speedy resolution.

 

[tuffyluffy 72]

The rhythm and noise sounds to me like compression exiting the engine, possibly through an intake valve?

Is there any blow-back coming from the air filter? 

Bit odd that its a not regular though.