First Timer

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Merlyn
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First Timer

Post by Merlyn »

After nearly 60 years in the trade I find myself today on a ship with 4 diesel engines fitted with spark plugs.
No, not glow plug/heater plugs ( although it does have them too ) but Spark plugs.
So what's the score here then?
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: First Timer

Post by D Winsor »

Maybe it's a modern duel fuel engine Diesel & LNG
It's my understanding with duel electronic fuel injection systems the engine can work as a diesel or operate on LNG but despite the higher compression a spark plug is still required to ignite the LNG
Troubleshooting 101 "Don't over think it - K.I.S.S. it"

Big Pete
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Re: First Timer

Post by Big Pete »

Dual fuel sounds better than Duel fuel!!
Those Gremlins have gotten in the keyboard again.
Auto ignition temp for Gas is higher than for Diesel so if you have the right compression ratio to run on liquid Diesel fuel the gas won't ignite, unless you have Pilot Injection of Diesel Fuel or spark plugs.
Conversely if you had a high enough compression ratio to auto ignite gas, you couldn't run on liquid diesel fuel, because of the "knocking" caused by premature ignition.

Big Pete
It is always better to ask a stupid question than to do a stupid thing.

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Merlyn
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Re: First Timer

Post by Merlyn »

Nice to hear from you again Dave and Big Pete and a happy Xmas to you and yours and all the best for the coming year.
This Diesel engine fitted with a spark plug for each cylinder displays some most peculiar traits many of which I have never encountered before.
For example a simple plug change consists of the following performance.
This is a two stroke three cylinder V6 engine and the manufacturer issues a Pie chart marked in degrees which must be adhered to at all times when changing spark plugs.
It is essential that the plug open electrodes face directly opposite the fuel injector ( Which incidentally is an air assisted Diesel injector, reminded me of the old blast air injection systems of yesteryear )
It also reminds me of the old days of attaching a 360 degree protractor to the front pulley with great accuracy, out with no 1 injector at TDC firing stroke and in with your clock gauge with the correct extension fitted and making sure the backlash is attended to in the right rotation carefully wind her over ( with the stop control out ) and for approx. 20 degrees BTDC for non turbo and approx. 23 deg degrees for turbo engines hopefully being displayed on the protractor.
The pump delivery valve holder being removed on no.1 to facilitate the poppet valve removal( don't lose the spring )
Back to the spark plug change the job is far from over yet.
Out with the box of maybe 12 plugs and selecting one screw it into the head.
Job done?
Far from it.
The plug has to have a line drawn down it from the top terminal down across the ceramic ribbed insulator to be directly opposite the electrode spark plug gap.
This was the line drawn done on my first ever motorcycle back in the early sixties done by other apprentices at the end of the working day to prevent my pride and joy from starting.
Once you know the score here it's easy but until that day off with the carbs. out with the distributor etc and you normally had to leave the non starter bike outside overnight and walk home.
Next day once other apprentices had shown you the quirk with your bike ( like flashing the headlamps 3 times within one minute or something else equally ridiculous ) the machine would obviously then start.
This ploy would invariably be continued until you sussed it out and did it to a juniors apprentices bike.
But I digress.
So here we have some 60 odd years later a manufacturer actually showing us in a tutorial how to draw a line down a spark plug which is essential prior to figment.
Now it's out with a wrist watch torque wrench which has to be set to 15-25 foot pounds.
Cast into the head are two lugs so should you not have your protractor not with you that day in your back pocket you have to aligne your non starter scribed lines between thelugs.
But here's the kicker.
The torque setting of 15-25 foot pounds has to be adhered to so when it's torqued up and your drawn scribed line is outside of the lugs cast in the head then that spark plug is not for you as it means the electrodes are not directly opposite the air assisted fuel injector.
So out with another plug and try again.
What the manufactors video doesn't tell you is what happens when you have exhausted all 12 plugs and the drawn line still sits outside the lugs?
Maybe this newfangled engine is scrap?
You can't shim it because the exposed threads in the head will coke up and then you'll have to retap it with all the carbon/swarf dumped atop the piston.
You can't leave the copper/whatever washer off the plug or contact with the piston may occur.
Plus it won't seal.
Trying to conduct this performance in a seaway must be something else to behold.
The tutorial now tells us that this engine has as its cold start device heater/glow plugs fitted into each cylinder.
These are obviously operated on a timed relay system as normal.
But what is not normal is this thing will not tick over or run properly at low rpm without the glowplugs being activated from a command to the relays from the ECU.
So a glowplug burn out ( which is a common occurrence ) will cause low rpm engine failure.
This arrangement is necessary of course to protect the envirement the blurb goes.
Yes, it's that emmisions yet again.
Now the manufacturers state this highly sophisticated futuristic super duper machine is NOT for the likes of us mortals but was designed especially for the US military as the result of a terrorist attack on one of their ships and as such is not available to us Joe Public type individuals.
So glad I am not in the military and having to change a plug under incoming enemy fire.
And yet I have seen four of these nightmare plug changers recently on a cruise ship and observed them in action.
Further clues?
They don't live down below.
Compression ratio of this "Diesel " engine BP?
6.1 to 1
Yes, that's correct 6.1 to 1
So here's your Xmas quiz to ease any possible chance of boredom.
To what do I refer?
What is it?
Happy Xmas to all and bring back some of the old contributors to the site I say.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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The Dieselduck
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Re: First Timer

Post by The Dieselduck »

Always a pleasure to read of your experiences Merlyn. Thanks for sharing... and thanks for the Christmas call too. I was surprised, pleasantly!
Martin Leduc
Certified Marine Engineer and Webmaster
Martin's Marine Engineering Page
http://www.dieselduck.net

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Merlyn
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Re: First Timer

Post by Merlyn »

No problem Martin, I am figuring ( as I believe you folks over there say ) that by keeping in with the Marine Engineering world version of the Man With The Sandals on that should I ever get tired of fiddling with flame ring protrusion heights etc that whilst awaiting a report from the Ginger One (who we have sent over there for a look see around ) I could well follow suit but without the press coverage supposedly being given.
Incidentally every one of my apprenticeship experiences are true and happened to me as told, save of course ( which I now have to confess to ) the boxed up liner job with the calcium carbide light atop the piston crown, it wasn't really lit when the head was whipped off p.d.q. overnight again, I embroidered the story to rivet the readers readings of same.
( think of that working out of the compression ratio by adding that measured liquid introduction to that removed injectorhole, that bumper clearance/ swept volume etc calculations of days gone by )

However I digress.
Back to the spark plug powered /air assisted injector/low compression so called Diesel engine machine whose time for a spark plug change depends on how many plugs you carry, whether you forgot your wrist watch torque wrench and if you can attain the 15/20 foot pound setting with the line you have to draw on the plug opposite the injector.
This "diesel" engine was designed for the US government by one of America's largest engine petrol engined makers solely as a result of the terrorist attack on the USS Cole, an American warship attacked at anchor by suicidal bombs and killed 17 crew members and injuring 39 others.
It also blew the stern off the ship by rendering a hole 40 feet in diameter.
It would appear that the fuel storage of the pre carried petrol engines greatly enhanced the fire thereby causing further deaths and injuries to the crew.
Powers to be decided that the so called "diesel " engine would reduce any further damage to the ship and crew although I have to say that it doesn't go anywhere near as well as the long established petrol engine.
This engine was only designed for military use but I have seen them on the deck of a cruise ship so it looks as though now it's available to all and sundry.
Looking at its design it looks to me like reverting to old technology ( blast injection etc ) but maybe like a lot of things nowadays it's here to stay.
But what is it?
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.

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