Medium speed marine engine: cylinder deglazing yes or no?? 2

[CapeNor]

I put this question here cause it looks like the engine site.

I'm engineer officer on a ship with 2 V12 medium speed HFO propulsion engines. For each cylinder, every 2 year, the piston rings are renewed, and every 4 year, the liner comes out to have a good overhaul. In both cases, the liner is honed by a flex-hone.

We now have a new chief engineer, who sends all the liners ashore for special deglazing treatment. He pushes us to take out all the liners within the next 2 years, instead of the usual 4 years... It costs plenty money (on a budget to short already) and ask plenty overtime that is not payed! It really upsets the officers and crew in the engine room.

Big question?? How can we see if a special treatment is required?? Or if a flex hone treatment is enough?? Is there a way to see if the chief engineer is right, or not?? There is no special ovality or special wear on the liner measured.

He claimes he wants to reduce the lub oil consumption that way.

Thanx for your reply

 

[Fabrico]

Can you find a way to measure and record oil consumption, cylinder leak-down, crankcase pressure, or blow-by? The Chief Engineer might even take an interest in a logical approach.

 

[CapeNor]

Hoi Fabrico,

There is a montly record of the oil consumption. The crankcase pressure is 4 cm H2O.

Both have not changed in the 4 years I have served in the ship's engine room.

Once the SB engine consumed more oil than the PS engine, but in the end, it turned out that the lub oil purifier on ps was not working correct. So I know for sure that at least have of the oil we consume is spend by the autocleaning of these filters.

We have had increased crankcase pressures, but that has always been due to a broken piston ring. (always... it happened twice the past 4 years)

 

[WGJ]

What is the 'special' deglazing he likes to have done?
From my (dated) experience of flexi-honing plus ring replacement, the oil consumption was better that the original factory hone gave.
This was on 6 litre direct-injection diesels.


Bill

 

[CapeNor]

I don't know what special treatment they do ashore. I didn't knew there were so many different ways of honing or deglazing. I will search it up next time.

But on the note with the liners, it only says "deglaze liner" . No specification...

 

[WGJ]

Sorry - I'm guilty of not previewing that last entry - Flexihone gave better resukts THAN the original factory finish.


Bill

 

[patprimmer]

I thought a flex hone was de-glazing.

A straight hone can correct out of shape and top ridge, but that is not specifically de-glazing.

The bottom line is you need cylinders with round consistent bores with straight sides. You need a deg lazed or textured surface to hold some oil and so the rings bed into the bore. End of story. Someone resorting to a solution to a non existing problem and bases that solution on semantics is generally hiding a lack of knowledge.

Identifying your bosses lack of knowledge may not help your career.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[WGJ]

PatP - "Identifying your bosses lack of knowledge may not help your career."

You can, as people say, say that again. I made a victim of myself a few times by contradicting a boss that came from another part of the company. It kept me where I am today. It's also difficult to get out of range when you've already shot yourself in the foot.

Norcape - good advice from PatP.
If I were you, I'd do as much as possible to learn about the issues around the 'poblem' and what others have learned in the techniques of fixing it. Practical, job-learned stuff (like using flexihone and so on) and perhaps some of the manufacturing and metallurgical stuff (honing processes and methods, slurry hone, plataeu honing, bore chroming, liner materials, liner castings, etc., etc.) and then say nothing until your "I'm right, you're wrong" boss shows his ignorance to his bosses.
Earlier on in the thread, the importance of collecting data was emphsised - do this religiously.
Some years ago, I was given a mundane task of data collection in support of an oil consumption improvement job on a small IDI diesel.
My senior engineer and I didn't get on. He was degree qualified from a respected engineering uni, I was a technician from outside of the motor industry.
It didn't take long to work out how dopey their data collection was. About all they were doing was logging cumulative oil use. It made it very difficult to see how one engine build spec compared to another.
All you had to do was differentiate the cumulative curves / plot the daily addition of oil with respect to hours run since the last addition and suddenly a new set of curves were produced that clearly showed the differences between the build specs and, after a while, developed into the typical "bath tub" curves that you see in the texts (break-in, constant use of oil, wear-out phase).
It went down, as we say, like a lead balloon. So, be careful if you value your career. Good Luck.




Bill

 

[CapeNor]

Well Bill,

Thanx for you're advice, but it' s to late I'm afraid. There have so much problems in the engine room. It's now in the hands of the captain and he has decided to put it up to the office technical department.

And since I'm senior third, I will have to do the talking...

Looks like I will stay 3rd for the next 10 years or so

Not so bad after all, who wants all the paperwork of the 2nd anyway???


what the details of the "deglazing" are... nobody nows. The boss refuses to give a technical answer, but if I look at the measurings, They have not straigtened the liner, they have not removed ovality (there was nearly none), It looks like if they just honed it. Maybe the "grooves" are a little deeper as when we do it with our flexihone?? but I'm not even sure about that one...

Well, everybody on the engine room floor is by now convinced that its a useless waste of money and labour...

Nice ...

Greetings

 

[WGJ]

I'll raise a drink to you this weekend.

Has 'the boss' got shares in the company that 'deglazed' the liners?


Bill

 

[evelrod]

Norcape, you have the sympathy of another member of the 'foot in mouth' club, BTDT!
I have deglazed cylinders with a Flexihone for more years than I care to remember...sounds like a 'boondoggle' to me.

Bill, to paraphrase Master Yoda, "A degree a qualified engineer, does not make"!

Rod

 

[WGJ]

Master Evelrod, the farce is with them always.

I managed to get a degree at the age of 49 after a bit of a set-to with a bone-headed ba#tard of a Manager decided he didn't like the way I got stuff done. Had to, just to stay in the job. The Company paid for it, so I just had to put the work in. I suppose you don't get to be an old tree unless you bend in the wind - was that a Jedi thought, I wonder?

That said, I've seen a lot of BS about the place over the years and it would have been put to better use on my garden.
Fertilizer seems to be the currency of some organisations.

Top man, that Yoda.


Bill