Diesel engine Overspeed

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Pengze
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Diesel engine Overspeed

Postby Pengze » Thu Jul 23, 2015 3:36 am

Why does a 4-stroke diesel engine Overspeed ?
Would appreciate your professional comments.
Thank you.

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Big Pete
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Re: Diesel engine Overspeed

Postby Big Pete » Thu Jul 23, 2015 7:23 am

Ingestion of flammable gas through air intakes,
sudden reduction of load when running at full load, e.g. weak link in coupling failing, alternator tripping of the board etc (Governor should respond but...) Fuel racks / fuel pumps / governors staying stuck at high output when load is reduced.
Failure of control of gas injection on Dual fuel engines.
Failure of Governor (should fail safe but......)

BP
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Merlyn
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Re: Diesel engine Overspeed

Postby Merlyn » Thu Jul 23, 2015 11:39 pm

Running on its own red hot oil via turbo oil seal gone on induction side allowing uncontrolled ungoverned speed. If you have ever experienced this screaming believe me it will be photographed in the back of the brain forever. Only way to counter it is to close off its air supply and quickly which is not easy, or leave the area rapidly and how as conrods can travel great distances and at great speeds. Maybe they ought to bring back the old Victorian governor , the three balls and centrifugal jobby ?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Merlyn
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Re: Diesel engine Overspeed

Postby Merlyn » Fri Jul 24, 2015 12:36 am

Seems even now common rail engines are not exempt from the " running on its own oil " syndrome. Although the governor on CR engines I have worked on still control the fuel shutoff on the HP pump the signal comes from the CAS sensor ( crank angle sensor )to the ECU and the square Hall effect ( or otherwise ) waveform pattern can be measured using a Scope but a complete fuel shutoff would still not prevent or reduce the " running on its own oil " situation. To date I have not yet experienced a common rail engine runaway and as this is a very infrequent happening I wonder if anyone else out there has had a CR runaway situation concerning turbo bearings/ oil seals let go?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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JK
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Re: Diesel engine Overspeed

Postby JK » Sat Jul 25, 2015 12:33 pm

I saw the after effects of a 16 cylinder MAK taking off when the fuel pumps were assembled incorrectly. At 0 load, the pumps were delivering 20% fuel. It took 140 seconds for the engine to shake off a counterweight and proceed to destroy itself. One of the oilers had the presence of mind to close the fuel supply because you couldn't shut it down from the emer stop. It was a miracle no one was killed.

Another one that happened on BCFC, the fuel linkage dropped off the governor when the retaining nut fell off and the pin came out
If I remember correctly (please correct me if I got this wrong) there were several engines coupled into the gearbox. When the linkage fell off, the racks went to full fuel and the engine tripped off on over speed . They then had other engines trip off load, the ship was left without power and ended up going into a marina of private yachts.

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Merlyn
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Re: Diesel engine Overspeed

Postby Merlyn » Sun Jul 26, 2015 1:30 am

JK, I seem to remember the BCFC occurrence as the Queen of Oak Bay where amongst other happenings a castellated nut on the governor link bar vibrated off and let go because no split pin was fitted or incorrectly fitted. As I stated earlier in my article way back a similar thing happened here on a Ro Ro Norwegian ship which I was involved in the repairs of. This vessel ran away similar to the Queen of Oak Bay and into a marina and damaged a lot of Yachts and the Quay and pontoons. We had to repair the injection pump and linkages and design and fit a bridge stop control which was electric over air job. This was a single screw ship. The Queen of Oak Bay's report, Marine Investigation Report M05W0111 Horseshoe Bay BC 30 June 2005 refers.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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JK
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Re: Diesel engine Overspeed

Postby JK » Sun Jul 26, 2015 4:48 am

2005! No wonder I was forgetting the details! Time flies when you're swamped in your own job.
The governor control company involved fired the FSR who did the work and I'm sure the insurance companies had a field day..

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Merlyn
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Re: Diesel engine Overspeed

Postby Merlyn » Sun Jul 26, 2015 7:13 am

The report says they could not positively ID the culprit, Mr Nobody again I guess. Makes for interesting reading though.
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JK
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Re: Diesel engine Overspeed

Postby JK » Sun Jul 26, 2015 8:55 am

As me old 2nd used to ask, way back in the dark ages, what's the most important nut on a ship?
The loose one, of course.

And

For the want of a cotter pin the ship was lost

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D Winsor
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Re: Diesel engine Overspeed

Postby D Winsor » Mon Jul 27, 2015 2:52 am

I guess these days with the onset of highly automated engines that cannot operate without sophisticated electronics the saying "For the want of a cotter pin the ship was lost" can be changed to "For the want of a microchip or micro-switch the ship was lost"
Troubleshooting 101 "Don't over think it - K.I.S.S. it"

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JollyJack
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Re: Diesel engine Overspeed

Postby JollyJack » Mon Jul 27, 2015 8:48 pm

Sophisticated electronic control is very reliable, it WILL fail.
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Merlyn
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Re: Diesel engine Overspeed

Postby Merlyn » Tue Jul 28, 2015 1:47 am

Loads of sensors, ECU 's HP injection pumps/ injectors / actuators / loom repairs carried out unnecessarily , I have seen many common rail problems which I have to say in some cases I sympathise with, seen a Bosch CR system had HP pump and injectors replaced costing thousands of pounds, engine cut out after many hours of running still, got involved with the still occurring problem , after many hours of fault finding what was the intermittent problem? The green O ring on the rail pressure regulator valve had a minuscule flat on it which caused a collapse of pressure in the fuel rail every so often thereby causing the ECU to trigger a complete shutdown . Would run for weeks before stopping sometimes. This took me ages to figure, even with Bosch and other testing equipment. Took the job off the so called Bosch agent to boot. However, now I know this fault, together with many others its in my brain library so next time maybe go straight to it. Faults come to light whereby the owners have had the manufactures involved with a diagnosis of, well it's on the top of its limits so best replace it. Guess what? The faults still there. Thousands and thousands of pounds spent unnecessarily again. People I have met on courses confirm these happenings although manufactures are not keen to make these findings generally known. Intermittent faults not stored or erased after so many starts are definitely the worst , a nightmare indeed. If the fault says it's an O 2 sensor don't believe it. It could be the loom feeding it, the ECU not supplying the correct voltages as necessary and so on and so on. So up comes the O2 fault, you tell the owner and although it is at fault it's the symptom , not the cause and a load more money needs to be spent at the end of the day to rectify the problem. Diagnosis is a problem of elimination right down the line. So the best of luck to all out there who like me are probably daft enough to get heavily involved with CR in depth as I wish you well on this particular voyage.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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D Winsor
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Re: Diesel engine Overspeed

Postby D Winsor » Tue Jul 28, 2015 3:59 am

I just recently watched an episode of the Discovery Chanel television series "Mighty Ships" featuring the Heavy Lift Ship "Happy Star" that proves Merlyn's point.
On the show the Main Engine kept shutting down because of either failed sensors or other faults. In one particular case it took the crew almost 24 hour to find what turned out to be a bad section of communication cable and connector worth about a dollar and caused numerous faults through out the system.
Even with the benefit of Hind Sight and our own opinions on how best to handle the situation it is hard not to be sympathetic to the Chief Engineer being caught in a situation like that.
Hard to find intermittent issues that turns your alarm system monitor screen full of red alarms in heart beat, can make one want to operate with the key for "Safety System Emergency By-pass" very close at hand. Especially when running in confined waters like the Seaway where you can potentially be on the rocks within seconds of loosing power.
Troubleshooting 101 "Don't over think it - K.I.S.S. it"

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Merlyn
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Re: Diesel engine Overspeed

Postby Merlyn » Wed Jul 29, 2015 8:46 am

DW, Interesting read ref Happy Stars Breakdown, being a new ship I suppose that would have to be put down to the Newness Effect, you know the saying, " oh she will be ok when the newness wears off ", the times I have spent days trying to locate yet again intermittent faults, checking and testing all sensors, actuators, looms, ECU' s etc etc and finding no faults. Sail with the ship and never ever duplicate the faults. Leave the ship , now comes the nail biting waiting for that expected phone call which never came. So what was the fault? No idea was the reply. Probably a multi plug loom connection maybe? Who knows. The bottom line is no one will ever know. In the old days you knew when you had cracked it but now it's so very different. When CR came out I almost went to my old clothes cupboard to see if my short trousers were still there so I could duplicate my school leaving and starting out all over again, , so different entirely just like in a lot of ways starting over again , another world indeed. Went on yet another course last week and was now told some engines had 9 separate injections per cycle, pre, before, during, in case of, after, then after again in case of. Plus one up the exhaust for old times sake. How many will next year bring? And the emissions ruling, load of hot air is what they want to achieve and in my view they are well on their way with that one. No dropped pintles here nowadays. When asked by the deck crew " what was the problem then ?" The answer I learnt in 1960 and which still reads true today, " gorviendo valve operating at incorrect intervals mate " would be the standard reply and as such this would be bandied around the ship to the much amusement of the engineers in the know. Truth is we knew as much as them, zero but bullsh t baffles brains and of course we had to remain the "experts " at all times.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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Merlyn
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Re: Diesel engine Overspeed

Postby Merlyn » Wed Jul 29, 2015 8:49 am

PS, wonder if PV/T = C anymore?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.


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