ChrisJ1978 said..
Gday all, just wanted to ask the brains trust what they think of my engine. It's a Nanni 3.100HE of unknown age and dubious hours (the gauge says 240.2). It seems to vibrate a lot at idle, I thought a 3 would be smoother. Please watch my 5 second YouTube video and let me know what you think...

Nope a 3 cyclinder will indeed rattle. In fact my mates Perkins 4236 ( 4 cyclinder ) rattles like hell at idle (fantastic engine though). The old Detroit 371 used to be rattly, loud, and leak oil. But was reliable. It was used as a generator on my dads old trawler. There's one running.

Id say the mounts are shot, thats excessive movement. Get someone to put it in gear and give it some revs while you watch it. Id be betting the whole motor pushes forward and possibly out of alignment maybe flexing the shaft as well.

woko said..
Yeh I tend to agree that the mounts are a bit wobbly, the engine its self sounds like a good little simple diesel. How about vibration when steaming ? Or is it just giving vibe in neutral idle ?

Now that i look at them those engine mounts probably are worth a look. The rattling should start to calm down a bit with more revs.

I agree with all above. Check those engine mounts. A 3 cylinder engine should be as smooth as silk and from the sound on your vid that engine sounds ok. I said ok, not perfect.

Diesel engines need to have the injectors pulled out, cleaned and tested on a regular basis (refer manual).

If you think your engine is running rough, have a listen to my 2 cylinder Yanmar. This is after a big service and engine mounts being adjusted.

Hi Chris
I was waiting for some who actually has a 3 cylinder Nanni to hop in.
But no one yet. .
There have been a good suggestions so far but I have a couple of questions
1, Is this boat and engine new to you?
2. Have noticed that this vibration has just started recently or has it been like that since you got the boat?
3. Is the engine fitted with a tachometer , if so is the engine idling at the correct RPM?
(from the video it seems that the engine is idling at about the right speed but often just a few hundred revs difference can cause vibrations)
4. Does the engine smooth out at higher revs?
5. Is there any difference (at the same revs) between the engine running in neutral and in gear?
6. Can you see any black powder around the engine mounts that would indicate the the steel mounts have devulcanised (just made that word up) form the rubber?
( The steel parts and the rubber parts of a damaged mount will rub against each other and create a black rubber powder)

My guesses would be.
1 idle speed set to low.
2 misfiring cylinder
3 worn out engine mounts

1 idle speed set to low. This the easiest and cheapest solution.
Screw in the idle screw slowly and if the vibration smooths out you are done.
A fast idling engine will warm up properly, run the alternator efficiently and usually run smoother ( but louder).

2 misfiring cylinder This can be caused by a variety of reasons. Partially blocked air filter, incorrect valve setting, worn valve seats, worn piston rings, partially blocked injectors. But don't panic I am just listing things, not suggesting that you need such drastic action.
Most of these things are caused by age or lack of maintenance. From your video the engine doesn't look too bad, but the black dust from vee belt wear could indicate poor maintenance.
If you have a mind to you can crack open the fuel supply line nut on each cylinder and see if how much difference it makes to the running and vibration.
It will also tell you if one cylinder is under-performing.

3 worn out engine mounts As I have mentioned this can usually be identified by looking for the tell tale powder, But in some cases the mounts can sit there looking perfect and in fact be devulcanised. You can put a pinch bar under the engine and lift it a few mm and see if the mounts separate or hold together. If the mounts are gone, you have no choice but to replace them. A doable job for anyone with patience , basic engine knowledge and tools.

All the best
gary

Runs great with good power but just vibrates at idle speed, did from the start and still does.

This what I suspect., Bob.

Gary

stray said..
Id say the mounts are shot, thats excessive movement. Get someone to put it in gear and give it some revs while you watch it. Id be betting the whole motor pushes forward and possibly out of alignment maybe flexing the shaft as well.

Thanks Stray, I'll do that.

cisco said..
I agree with all above. Check those engine mounts. A 3 cylinder engine should be as smooth as silk and from the sound on your vid that engine sounds ok. I said ok, not perfect.

Diesel engines need to have the injectors pulled out, cleaned and tested on a regular basis (refer manual).

If you think your engine is running rough, have a listen to my 2 cylinder Yanmar. This is after a big service and engine mounts being adjusted.

Wow that is smooth! Do you mind telling me what you were charged for the service?

ChrisJ1978 said..
Wow that is smooth! Do you mind telling me what you were charged for the service?

Injector tip cleaning on one and replacement of the other was about $200.

Oil and filter, anodes and some hose about $100. One litre of fuel additive (of which less than 100 ml has been added) $120.

costeffective.com.au/product/ftc-decarbonizer/ This is good, as Ramona described it, "snake oil".

One litre of white vinegar, $1.50 and labour nil. How do I charge myself $100/hour?