# Changing a Liner



## double acting (Sep 14, 2008)

According to the after action report of Gunter Prein, and I quote " the lubricating oil was found to have 7-8% water in it. A leak in a cylinder liner was found to be the culprit. Chief Engineer Johann Frederick Wessels was called up on the apply all his and experience and expertise Eventually all was rectified"

How long would it take to replace the liner in an MAN four stroke, as fitted to the U 47?

This occurred en route to penetrating Scapa Flow


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## OilJiver (Jun 30, 2014)

V difficult to estimate. Weather a considerable factor. How many experienced tech staff? Access for working (including cleaning/securing all dismantled parts etc) leaves little to imagination.

That said, 4 men, 12 – 18 hours??


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## Clifford Cocker (Jan 21, 2008)

*Changing liners*

Have been involved in changing Doxford liners, one at anchor in Sunderland Bay in November, ship rolling did't help, and one in Hong Kong at anchor.
From what I can remember both occasions were at least 24 hour jobs, the one in Sunderland Bay even on a new engine was delayed by the fact that all the tools were still crated (to avoid pilfering in the Yard) and only 2 of us (the Chief and myself, 2nd) had experience of "J"type engines. 
The one in Hong Kong had the usual problems like seized up exhaust manifold bolts.
Cliff Cocker


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## Farmer John (Feb 22, 2012)

With a very broad brush and great latitude for a complete fool, what do you do to achieve this? Marine engineering always seems such a massive achievement.


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## vickentallen (Oct 12, 2007)

Thoughts on changing liner while submerged ? and under motor (electrical) power, not so much Rolly-Polly. also if like AMSDs , designed for relatively straightforward disassembly


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## Steamseadog (Apr 11, 2008)

Hi,
Remember changing J type Doxford cylinders. Things that slowed the job down were removing the exhaust belt from the liner and lapping in the 2 face to face joints on the combustion/cylinder faces. We gave up with one belt and sent it ashore. They used a 100 ton impact press to free it up. We had no chance with Monday hammers. Also involved in changing cracked DA Burmeister liners in the Red sea. These 3 pce liners were not the same bore. The main piston was larger than the exhaust pistons and were difficult to work with. The 3rd Engineer was the main engine man. With a squad of Chinese the job was done in 12 hrs. After the job was completed the poor bloke was told that the other engine had also cracked a liner and it really got to him. Handfulls of salt tablets and kettles of ice/water kept the squad on their feet


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## Tony Foot (Sep 25, 2012)

Having worked on both MaK and MAN trunk piston type diesels, the procedure would be something like as follows.
Remove all coolant, fuel and lubrication pipework from the cylinder head.
Slacken all inlet and exhaust manifold bolts and remove those on the head in question.
Remove valve rocker assemblies. Then loosen cylinder head nuts and remove head.
If the leak was caused by the head joints, then clean up area, fit new joints and reassemble engine. Time taken in panic mode about 4/5 hours. Normal mode about 6 hours.
If the leak is caused by a cracked liner, remove cyl. head as above then; Undo bottom end bolts and lower bearing cap. fit piston extractor and remove piston complete with connecting rod from the engine. Fit liner puller and remove liner from the engine. Clean up all mating surfaces and fit new O"rings and top joint and press liner back into place. Refit piston and all other components, slacking the adjacent manifold bolts will give enough clearance to refit Cyl. head and manifold joints . refit head and pipework and job done. Panic mode about 8/10 hrs. Non panic 10/12 Hrs.
Assumption here being that Naval vessels get regular major overhauls and that it wasn't a rustheap. Panic mode works on the principle that the engine was working before so all clearances etc. are ok unless obvious problem evident, also just the necessary minimum of cleanup. Non panic allows for checking Clearances, gaps etc and a good cleanup of everything.


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## Farmer John (Feb 22, 2012)

Thank you very much for that, Tony. I am glad I never was an engineer, but your description helps understanding a lot.


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## colcur (May 15, 2017)

Sulzer RND-M engines had a propensity for liner cracking. Changed at least one liner per trip and became quite adept at it.


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## Varley (Oct 1, 2006)

My first two motor ships were Gotaverken engine and it was routine to 'do' one unit, at least every voyage. The next (and last) was B&W. When I wondered why I had not seen it inside-out after one trip I was thrown the line "you must have come from a Gotaverken you don't need to here".

When I did, it was following departure god forsaken Dampier with turbochargers surging and a fuel valve that refused to come out even with the head inverted and a lump hammer employed.


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## sternchallis (Nov 15, 2015)

Varley said:


> When I did, it was following departure god forsaken Dampier with turbochargers surging and a fuel valve that refused to come out even with the head inverted and a lump hammer employed.


Had similar experience after changing fv in Bremen. All but one fv wouldn't come out the pocket. The supplied drawing gear required the pressure adjustment removing. The fv was that tight it buckled the drawing gear. We were about to sail so the 2nd said put the pressure adjustment back.
We got up to F.Ahd when the exhaust temp shot up on that unit.
After trying various wedges and crow bars the fv still wouldn't move.
It was decided to remove the cylinder cover. I then suspended the fv from the ER crane and block up the other side of the cover and two of us struck the cover either side of the fv with mondy morning hammers. Still nothing.
It was 0dark100 and most of us had been up since 8 am.
We then decided to clean up the spare cover and and fit that with two new fv's.
After the 4 month voyage and laying up in Barry, the repair people sent a 6' fitter and his lad to knock the fv out. Why we could not have done that on the voyage I don't know? The reason for it sticking was too many 'O' rings under the fv so it wasn't seating on the face to face in the fv tube causing gas blow by and carbon fouling. Both the fv and the bottom of the tube are supposed to be lapped, if this had not been done , but an extra 'o' ring fitted then this would have caused the problem.

There were 3 new 2nd's tickets and a Chiefs Motor endorsement with their signatures still wet when we joined, it was the ex cadet that got the 2nd's job and I was made up to 3rd , though got my 2nd's job on my next ship, a new Brazilian built general cargo and I had my own fun and games on that one. Baptism by fire was that.


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## dannic (Mar 10, 2013)

On a 6 cylinder B&W in 2 x 4 month contracts as second engineer I renewed 14 liners, cannot remember how many pistons overhauled as well. Towards the end of second trip we could do two liners overnight!
Dannic.


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## sternchallis (Nov 15, 2015)

dannic said:


> On a 6 cylinder B&W in 2 x 4 month contracts as second engineer I renewed 14 liners, cannot remember how many pistons overhauled as well. Towards the end of second trip we could do two liners overnight!
> Dannic.


I believe the early poppet valve B&W with the 4 springs used to eat liners until they made modifications (not sure what they were). 

I was on 3 and only came across a cracked liner on the one above. This happened not far from Miami, so the company in their wisdom got shoreside into do it. When the repair company was informed , they scoured the US for somebody with B& W experience.
The chap they found had never seen a poppet valve, only 4 posters.
Why we weren't allowed to do I don't know. Perhaps the 2nd being new and the Chief being a steam queen.


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## D1566 (Sep 7, 2009)

U-47 had Germaniawerft F46 four-stroke, six-cylinder diesel engines, small by Merchant ship standards but still substantial sized liner to remove.
From the description of the problem, I would imagine that they would have removed the liner to replace the seals and then refitted the same one, still a big job. 12 hours for two men? Would they have carried enough Lub Oil to do a complete change I wonder?
https://goo.gl/images/XKQMiG


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