MAN V10 - 1050hp LE403s

I've never notice water ripples except at the exhaust , but must say I don't think I really looked. But I am in the engine room alot at idle. I think I could put a marble on either of my engines at idle and it wouldn't roll off? (slight exaggeration). Neither the springs on the airseps, nor hose and wire bundles have any visual vibrations. I have analog tachs, but they read rock solid, and running on a single engine I have a very even 'push" thru the water. Are all your engine mounts snug? Sometime the nut will vibrate free. I'm sure there are myriad other more plausable possibilities ....

Hey, why don't you read what I wrote, rather than making it up on my behalf?

YOU are reiterating to boredom that your engines are smooth, while it's widely known (no matter how happy you can be about them, which I never argued against!) that V12s are smoother.
In fact, the behaviour that motoryachtlover describes is in my experience completely normal.

YOU used the expression "The cutout actually closes the injectors", which is misleading because it's perfectly possible, but only with electronic injectors, which do not require any sort of "spigot off", to use your own wording.

Last but not least, I literally said "I'm not insisting" on the cutout feature. What else are you expecting me to say, in order to reciprocate?!?

"And as all other MAN mechanical engines, it didn't have any cutout system" your words.

Quote correctly. My words were "close the injectors, I believe...."

We were comparing 10 to 10 cylinder idles not 12 cylinders.

But lets cut it off. I have no gripe with anyone personally, just bad info that's presented emphatically.

I have 820's in a 53' Viking recently purchased. It had a very rough idle and at sea trial an injector was leaking severely. We cut the sea trial short replaced the injector and it ran much smoother. I have since replaced the other 19 injectors. You can certainly feel the cylinder cut out feature but if you bump up RPMs by about 25 it really smooths out. I too have been using 1 engine in no wake areas at about.
Beau what RPMs are your idle set at?

The analogs show about 600. When the motors are hot after a trip they run up about 700. So you have the same experience as I of having to suddenly swing the helm like a drunk when some one does something a bit foolish in front of you in the narrow channel?

Bosch injectors/nozzles are indeed crucial in these engines.
Not because they aren't reliable - it's actually the opposite, in general: they are less sensitive to dirt or watered fuel, when compared to more modern, higher pressure injectors.
But if and when they leak, in the worst case they can lead to severe piston damage.
So, I think you did the right thing pulling also all the others.
Replacing them is almost unheard of, though: normally, any good Bosch service can refurbish them, i.e. replace the nozzles, tune opening pressure, and they are as good as new for at least another thousand of hours.
Of course, during such check, they also verify if any replacement is necessary, but I'm aware of a boat with 4k hours on her V12s (whose injectors are the same as in V10 and V8), and none of them have ever been replaced.

Ref. idle RPM, I'd suggest to use a laser tachometer to check it, because the accuracy of VDO analogue gauges usually mated to these engines leaves something to be desired.
It's only 20 bucks or so, and dead easy to use: you stick a piece of reflective tape on the belt pulley, and you're good to go.
Btw, that's also useful to sync the engines exactly at cruising speed, cross-checking what the instruments show.
In my boat, I cruise mostly at 1800 rpm, but after checking with the laser tacho I found that I'm perfectly in sync when the needle is a hair above in one engine and a hair below in the other.

Funny... Yes in fact on last trip I was coming up a narrow canal and a boat towing about 10 docks turned across my path... that was both engines reverse!!!! I think I need to turn up the idle. Typically they are at about 550. I do notice they are much smoother at 600. At 600 I need to bump in and out of gear quite a bit.- Thanks

I should clarify that re-built injectors were put in. The valve lash was set at the same time which could have helped them to run more smoothly. I was on a very tight schedule and didn't have time to pull and test the 19 remaining. I have digital tachs in the engine room and yes the VDO analogs are off by a little bit. Thanks for the additional info.

One one engine, we putt along at around. 5.6 knots I don't have the stern deadrise that you do. My 600 could be a 550? I might try Mapism idea just for better info. Ain't changing a thing though, since they are running just fine

Do you mean permanently wired?
If so, I'd be curious to hear more about them, because the original engine control box designed for e/r installatiom (which was a MAN option), aside from start/stop and a few basic instruments, featured the very same analogue VDO tach which was normally fitted in the dashboard.

yes they are permanently wired digital tachs in the engine control boxes. I'm not sure what brand. I could take a look when I'm back on the boat tomorrow. Since the instruments on the bridge are looking a little worse for wear I was thinking about replacing the VDO with Digital tachs and then updating the other gauges to newer VDO. I was told during engine survey that the digital tachs were exact. I am running about 5.6 also at 550 RPM.

X2. It is an interesting experience dialing in the operation. I am currently berthed at Charleston Harbor Marina and like most Charleston Marinas the current is nuts at times- Other than the mega dock. It adds a nice twist for me with the amount of thrust those props throw and the current in my berth is at a 45 degree angle into or away from finger pier. No dock or pylons between boats in slip either.

More than just heard, I've actually seen a holed piston due to that.
But I'm not sure if that had anything to see with the brand.
Actually, I wasn't even aware that MAN ever used anything else than Bosch, are you sure that they also fitted Monarchs?

Anyway, as I was told, this doesn't happen out of the blue, but it's rather due to progressive oxidation/degradation, possibly due to lack of use, rather than excessive.
The two tips I was given, and which I included in my routine checks, are as follows:
1) upon cold start, particularly after the engines stayed unused for some time, look for spots of fuel floating on the surface near the exhaust ports. There should be none at all, normally;
2) once warmed up, smoke at idle and low rpm should be low, and comparable in both engines.

FWIW, I refurbished the injector (new nozzles and pressure check/adjust) on my boat at almost 1500 hours, not because of any particular problem but just as preventative maintenance.
None of them was too far from rated pressure, just generally a bit lower, by somewhere between 10 and 20 bar at worst.
No leaks, but the nozzle spray wasn't as regular as it's supposed to be.
Since that job, I didn't see any meaningful performance improvement, but I did notice much less soot on the hull sides (almost none, in fact), around the exhaust bypass.
Which gave me some confidence to not have thrown money away for nothing...

Sounds interesting, thanks in advance for confirming the brand/model!

I checked this morning. The digital tachs are made by Aetna Engineering. I couldn’t see the model number but I checked their site and they appear to be model 8402R-P-DS.

Great, many thanks.
As I understood from Aetna website, I guess the instrument must be feeded by their 8901 senders, installed somewhere on the engine.
If the next time you'll be onboard you would have a chance to check where the sender goes, I would appreciate!

Well, considering the multiple sources, that's more than likely correct, I suppose.
Sorry to have relayed a wrong indication, regardless of how reliable my source was - or should have been, theoretically...

Yes, it's the right bank of cy;inders.