...and how is your morning?

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The Dieselduck
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...and how is your morning?

Postby The Dieselduck » Mon Dec 10, 2012 6:07 pm

Came down for watch, the Fourth said the engine could not pick the load... wonder why?

Looks like the intake valve failed, and ended up splitting the piston in half, then, the connecting rod killed the liner, flooding the engine with coolant, which it ran on for a bit. Ahhh, good old Cat's always a flair for the dramatic. Remarkably, it does not seem like there is any damage to the block or crank, however, I think the conrod is bent.
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Martin Leduc
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JK
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Re: ...and how is your morning?

Postby JK » Tue Dec 11, 2012 3:24 am

Cats-they run 'til they stop and they stop in a spectacular fashion.
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Big Pete
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Re: ...and how is your morning?

Postby Big Pete » Tue Dec 11, 2012 9:00 am

A nice bucket of bits, I guess it kinda spoiled your day!!!
It could have put a twist in the crankshaft, I would check the positions of TDC for pistons each side of the damaged unit to see if the crank has to be replaced. Deflections wont show anything.
Might also be worth checking the main bearings and journals, dye pen for cracks and visual check.
Shrapnel could have gone through the turbo and damaged that.
The water pumped through the LO system could have reacted with the Tin in the white metal bearings to form Tin Hydroxide, if that is then exposed to air it will convert into a Hard Black Tin Oxide, which is harder than the crankshaft or camshaft and will destroy them, if that has happened the bearings will have to be replaced or cleaned up with pan scourers until the hard black layer is removed.
I don't suppose you will be wondering what to do on watch for a while.
Good Luck Martin and Merry Xmas!!

BP
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JollyJack
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Re: ...and how is your morning?

Postby JollyJack » Tue Dec 11, 2012 10:47 am

It's things like that makes me glad to be ashore now :) been there, done that, got the scars :)
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JK
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Re: ...and how is your morning?

Postby JK » Tue Dec 11, 2012 12:36 pm

nice thing about Cats is you get remanned parts and get a good warranty with it plus the core cost. Always a joy though when they drop a valve.
Now you have to look at the hours on the top ends of the other engines. If the maintenance is not done at the specified hours, this is what happens,guaranteed. When Cat says 8000 hours, that is what you get.Where this is a generator I doubt if it is overloaded, like could happen like it was a propulsion engine.

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Re: ...and how is your morning?

Postby JFC » Tue Dec 11, 2012 3:08 pm

Martin,

You may have dodged a bullet with the block, but I doubt you will be successful with the crank.

Crankshaft may be twisted, and hence damaged beyond repair.

Been there done that too.....

Cheers

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The Dieselduck
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Re: ...and how is your morning?

Postby The Dieselduck » Thu Jan 03, 2013 11:34 am

To update those interested...

Well, the engine is back on the board. We completed the rebuild this morning. It was actually working just fine about a week after initial failure, but we had found further damage that was missed originally, that we did not wnat to leave to chance. The biggest challenge was getting tech and parts during the holiday season.

In the end, it would appear we were very fortunate in this failure. No damage to the block or crank were noted. The affected hole, #7, the pictures indicate pretty accurately was destroyed, but the block spared. Number 8 hole had shrapnel damage, and the whole power unit was replaced. Despite, oil pan stiffening / baffle #5 piston also had a small chunk missin from its skirt, resulting in some damage to the liner as well - so it was replace. Thats what we finished up yesterday.

One of the turbos was toasted, new installed. After initialled start up, we noticed oil leaking from turbo flangeg. After troubleshooting we pull cylinder head on 1-3, and found exhaust valve on #1 loose, its guide being wore out. So we replaced that head. She must have leaked quite a bit of oil, cause after that, we still had considerable oil leaking from turbo flanges, which threw us for a loop. So we replaced again the turbo, but in the end, must have been residual in the manifold, as it sort itself out under load - and never came back.

I had never workd on these engines before (onboard we have V8 500 hp Cat D397, V12 750 hp Cat D398, and the 1000 hp V16 Cat D399) very simple machine full of iron. However I would like to get the designer over to have a few words with him on the exhaust bolting. That guys needs to bone up on the impacts of his design vis a vis serviceability.
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offshoresnipe
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Re: ...and how is your morning?

Postby offshoresnipe » Fri Jan 04, 2013 9:41 am

Ah the joy of Cat's, it is great when you talk with a Cat mechanic, he will say " oh I never do it like the book, you got to take it down to there to get at that".

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JollyJack
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Re: ...and how is your morning?

Postby JollyJack » Fri Jan 04, 2013 7:12 pm

You miss the point on why Cats are made the way they are. They are not designed to be run and maintained, they are designed to sell spare parts.
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JK
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Re: ...and how is your morning?

Postby JK » Sat Jan 05, 2013 5:05 am

Have to agree. You run them until they are at the hours or dead then get service in.
The first time I dealt with them on an engine job, I finally said in exasperation to the Service manager that all of the techs must have been on commission. Then I told him if they put another part in without my authorization, they wouldn't get paid. That slowed it down somewhat. :roll:
The D399 are old engines. They are the model you can't find fuel pump casings for anymore.


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