One MAN engine fails on last day end last trip of our summer holliday’s

[Divemaster1]

Feel for you Bart ....

Good luck and hope it is a simple fix!

Irrespective... watch your hands when working on the engine... particularly if lifting heavy items..

 

[rafiki_]

Sure it could start. The break could be a long way along the crank from the flywheel (starter motor) end. It would run lumpier of course because the stationary cylinders would not fire when their turn came. The injectors would still squirt fuel into the dead cylinders, and the governor would squirt more fuel into the live cylinders because they'd be working harder to hit the rpm demanded of the governor, hence potential smokiness

This is why, unfortunately, the combination of busted dampener and smoky running and WOT blast for 5 minutes leads inevitiably to a worry of busted crank. It pains me to say it but that's what you gotta suspect on the info available. Dampeners are very important things

OK all possible I guess. The bore scope should show possible cylinder/piston troubles, not sure how you would check the webs without removing the sump.

 

[jfm]

I'd forgotten (doh!) tinkicker that timing will be at the other end (probably). If the crank is a few degrees out behind the break, then the timing will be a few degrees out on all the cylinders including the ones in front of the break, which is another reason for the smoke

 

[jfm]

OK all possible I guess. The bore scope should show possible cylinder/piston troubles, not sure how you would check the webs without removing the sump.

Often there are removable plates on the side of the sump, eg to allow you to hand the dipsticks, etc, or indeed to allow you to inspect the bottom end. That's where I'd look first if the access is avaialbe

 

[tinkicker0]

I'd forgotten (doh!) tinkicker that timing will be at the other end (probably). If the crank is a few degrees out behind the break, then the timing will be a few degrees out on all the cylinders including the ones in front of the break, which is another reason for the smoke

Nope, front cylinders timed perfectly. The only thing that changed is behind the break because of the load across the fracture. The front cylinders are pushing against the fracture, the rear are lagging because of the load from the flywheel end making some slippage in the fracture site.

Assuming front timed motor and hypothetically of course.





Edit. Sorry Bart, I did it again. I must sound like some talking head on the news, ghoulishly dissecting the latest rail disaster.

I really hope I am wrong and your pride and joy recovers without too much distress. You sometimes forget you are discussing someone's most prized possession. Used to dealing with impersonal corporate types who view it as the cost of doing business, rather than private individuals who can ill afford the expense and the upheaval.

 

[jfm]

Nope, front cylinders timed perfectly. ... Assuming front timed motor and hypothetically of course.

Yup, I see your point - thanks

As matter of interest, having seen the pic in BartW's post above and given that you manage this work all the time, how would you see the job being done? Strip ancilliaries off engine, lift block up a foot and a half, and fit crank from underneath? Or is that a daft idea because of the practicalities of lifting a heavy crank up into the shells? I mean, does the engine have to come out and be put into an assembly station and turn sideways/upside down? Does the block have to come out of the e/room?

I know it's jumping the gun with this question but I'd be interested in your view of how practically you do a crank in a motor this big with limited access for gear, I mean as a general question even if BartW's boat (hopefully) doesn't need it

 

[MapisM]

None too happy with the smoke and rough running.... after damper failure. Hope it not a web fracture.

the combination of busted dampener and smoky running and WOT blast for 5 minutes leads inevitiably to a worry of busted crank.

Understandable concern folks, but that's not what actually happened, I reckon.
B said in his OP "I reached the marine, and could maneuver in my berth, still a lot of noise and rattling and vibration, but no unusual smoke"
And only the following day, upon cold start, he got "a lot of smoke".
TBH, I can't think of a sensible alternative explanation, but how could a broken crank NOT have caused smoke immediately?

Anyhow, all the very best B for a less serious and more easily repairable damage.
If nothing else, 25kts @ 2350 on both engines was indeed impressive for a vessel like BA, and that would make me think that up to that point the engines were doing a fantastic job....!

 

[tinkicker0]

Engine running, thrust on fracture from front cylinders. Engine being cranked over, thrust on fracture from flywheel end = slippage of the failure site.

JFM. Engine out to ensure deep clean of oil galleries and full inspection of block integrity would be best. It may be that a line bore of the crank saddles is required even if no apparent damage otherwise. Best not to try to cut the tar ration and ruin the ship at this juncture.

 

[Latestarter1]

Sorry but I feel a quick history lesson coming on.

The MAN/Mercedes modular engines are/were the result of a 1960's JV to produce IL 5 and 6, V6, V8, V10 and V12 engines. MAN tended to use the inline engines in trucks although the V10 did feature in top range heavy trucks, Mercedes used the V6 , V8 and V10, but the IL6 in buses.

All used many common components, for example a cylinder head from a 10 liter IL5 MAN would fit a 21 liter V12 Mercedes.

Now cutting to the chase, this huge degree of modularity had one major drawback, bearing areas of these engines is very small as bearings are narrow, however at the time this was not an issue because at the outset these engines were NOT designed for turbocharging, for example the 18 liter V10 used by both companies had an output of 350 hp in NA form. However life moves on and the move toward pressure charging for improved power density and emissions has led to far higher outputs than originally envisaged by the designers.

These are very light engines for their displacement with a long skinny crank on the V10 and V12 combined with small bearing area resulting in a hotbed of torsional activity which is why I was surprised that the engine in question has a bonded rubber damper, when a viscous damper appears more appropriate. Crank failure of high output V10/V12 is not at all unknown, just ask any operator of very large (100tonne) mobile cranes.

I was a little reluctant to pile on the pressure of conjecture too early, however reason for the history lesson is to end on a positive note. Sheer numbers produced mean that crankshafts for these engines are not megabucks, for example a crank out of the old Mercedes Atlas foundry in South Africa should go straight in.

Good luck

 

[BartW]

Thank you all so much for your advice, comments and sympathy,

Sorry to have opened my big mouth and worried you. Should have shown a little more tact, but in my line of work you tend to get a little "clinical" about such things.
No point getting het up yet, it may be just the damper and you looking at things a bit deeper than normal.

no, no, don't worrry, don't cover your thoughts,
just in this thread I have learned more about big diesel engines than ever before,
thanks for all the info , and pls don't hold back !

 

[BartW]

Feel for you Bart ....

Good luck and hope it is a simple fix!

Irrespective... watch your hands when working on the engine... particularly if lifting heavy items..

when talking about the engines, very often I think about you Alf,
you explained us regulary that your DD's are very traditional easy to service, easy to get info, easy to get spares etc...

well I think more or less the same about my engines, except they are 4 stroke, and slightly more modern, if I may say
but nevertheless fully mechanical, easy acces everywhere, info and parts easy to find,

lets hope I can keep this opinion in the future :ambivalence:

 

[BartW]

Yes they are surprisingly cheap. I suggest google Sealey Boroscope. I bought the £100 one with 8.5mm dia probe. It records onto SD card as well as showing the picture on the screen in real time. The probe has LED light. It's a very good device for the money. For much more money @£400 they do one with 4.5mm probe but I think all the glow plug/injector holes on big engines like yours will accept 8.5mm dia

I would want to look with boroscope at the crankshaft by opening a plate on the side of the sump. Alternatively put the boroscope into the injector/glow plug hole of the cylinder furthest away from the flywheel and turn the engine with spanner on flywheel ( or starter motor maybe). If that cylinder moves ok in a full up/down cycle then the crankshaft must be ok

Fingers seriously crossed here. I hope I am being far too pessimistic and that it is something less serious. It's hard to diagnose from a keyboard anyway. Unfortunately crankshaft dampers are important parts of an engine (to stop the torsional harmonic dancing) and if yours has been bad for a while then I fear the consequences. Crankshaft work is major surgery in a boat, as you know, though if anyone can do it you can!). Fingers very much crossed for you Bart

Borescoop is ordered, the 4.5 mm model, sometimes we can use such a device in the company.
thanks for the advice !

 

[BartW]

As matter of interest, having seen the pic in BartW's post above and given that you manage this work all the time, how would you see the job being done? Strip ancilliaries off engine, lift block up a foot and a half, and fit crank from underneath? Or is that a daft idea because of the practicalities of lifting a heavy crank up into the shells? I mean, does the engine have to come out and be put into an assembly station and turn sideways/upside down? Does the block have to come out of the e/room?

I know it's jumping the gun with this question but I'd be interested in your view of how practically you do a crank in a motor this big with limited access for gear, I mean as a general question even if BartW's boat (hopefully) doesn't need it

yes you can read my mind, I've been wondering myself,
but rather choose between the options:
get a experienced engineer to do the work in the boat,
or get the engine out and bring it here in Belgium to a well known rebuild center nearby

I'm mostly concerned about the logistics involved,
now the boat had be better in SOF,
but I do have a driver who did the trip already 2 times; 1860km

 

[BartW]

Understandable concern folks, but that's not what actually happened, I reckon.
B said in his OP "I reached the marine, and could maneuver in my berth, still a lot of noise and rattling and vibration, but no unusual smoke"
And only the following day, upon cold start, he got "a lot of smoke".
TBH, I can't think of a sensible alternative explanation, but how could a broken crank NOT have caused smoke immediately?

you're right with your correction, but I have to point out that after the WOT, the engine continue to run, and cause vibration,
so I rather think, its my big mistake not to switch off that engine immediately,
and that the continued vibration during +/- 20 minutes has done the damage,
caused fracture in the crank webbing, ...etc
just before stopping the engine, I noticed a raise of temp, above 90°C, at least higher than normal.

Anyhow, all the very best B for a less serious and more easily repairable damage.
If nothing else, 25kts @ 2350 on both engines was indeed impressive for a vessel like BA, and that would make me think that up to that point the engines were doing a fantastic job....!

exactly !
despite all observations and comments on these engines above, even if these are lightly built or whatever, I was really pleased with them !

 

[MapisM]

Engine running, thrust on fracture from front cylinders. Engine being cranked over, thrust on fracture from flywheel end = slippage of the failure site.

Doh, I'm afraid this makes good sense, I didn't think about it.
Just another thought before BartW gets too involved in the engine repair and forgets that: I'd rather replace that stupid rubber damper also on the other engine, just in case!
Again all the very best, B.

 

[Latestarter1]

Bart,

These engines have been around for a lifetime, provided that they are understood perform sterling service.

When I was in South Africa the Mercedes V10 in heavy truck applications was the backbone of heavy transport during sanctions. Operators preferred Cat 3406 and Cummins NT855, however they could only purchase second hand. The V10 would go to a first life to overhaul of 1.5 million km, same as Cat 3406 and Cummins NT. Second life Cat and Cummins were still good for 1.5 million km whereas V10 Merc went down at 1.0 million km. Third life overhaul required re-block as it was all over the place by this time.

Whilst Cat and Cummins were 14 litre node engines Mercedes V10 was 18 liters the American motors had 30/40% greater bearing area and were seriously heavy metal when compared with the Mercedes V10, however 2.5 million km pulling big loads is no mean feat for any engine.

Just wanted to make the point that these are good motors but detailed maintenance is vital, plus the fact that parts availability will not be an issue.

 

[Richard.C]

All used many common components, for example a cylinder head from a 10 liter IL5 MAN would fit a 21 liter V12 Mercedes.

Of no real matter to this conversation but did you mean the IL5 cylinder head would fit the V10, you would seem to have one too few cylinders otherwise?

 

[BartW]

Just another thought before BartW gets too involved in the engine repair and forgets that: I'd rather replace that stupid rubber damper also on the other engine, just in case!
Again all the very best, B.

shure, was planning to do that,
and as LS sugests make sure that the engine(s) gets all the cheque-ups and service that are needed.

 

[BartW]

Of no real matter to this conversation but did you mean the IL5 cylinder head would fit the V10, you would seem to have one too few cylinders otherwise?

as I understand it, and can see on the drawings;
each piston has a separate / individual cylinder head.

 

[Richard.C]

as I understand it, and can see on the drawings;
each piston has a separate / individual cylinder head.

In that case it makes total sense and I need to eat my words, I'll go back to playing with little car engines