# Liner Lacquering



## BLACKMIRRLEES (May 1, 2014)

Hi, Does anyone have experience with " liner lacquering " in medium
speed marine engines, and if so has the problem been overcome ?
I have noted a research report by a large oil company saying that their product overcomes it, but the report is accompanied by a photo showing the cross hatch pattern of a liner still clearly visible, but the photo is taken from below the piston,at the lower end of the bore, where the area of the liner bore shown would not be swept by the piston- rings anyway.


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## david freeman (Jan 26, 2006)

BLACKMIRRLEES said:


> Hi, Does anyone have experience with " liner lacquering " in medium
> speed marine engines, and if so has the problem been overcome ?
> I have noted a research report by a large oil company saying that their product overcomes it, but the report is accompanied by a photo showing the cross hatch pattern of a liner still clearly visible, but the photo is taken from below the piston,at the lower end of the bore, where the area of the liner bore shown would not be swept by the piston- rings anyway.


Is this the same as on a doxford or H&W BW Opposed sitting on a bosuns chair in the liner with a grinder in hand polishing the liner, so that the rings fitt better afterwards and one gets no blow past into the crankcase, and the chance of a crankcase explosion.
I know you quote medium speeds engines- however this case of lacuering may be caused by the modern engines burning very heavy fo 3500Redwood and above, heated for good combustion (300)'Farenhiet ( I may have this wrong?), but not been able to remove the fines, it is still crap fuel, and the oil companies do their best to lubricate the engines. Remeber a 4/stroke 2/stroke medium speed has no specific oil liner injection like the old B&Ws and Doxfords, the liners rely on the splash back from the crankcase and the piston skirt doing the lubrication of the liner, or leakage/spill past from the top end/guedgeon pin.(H)(Cloud)(Ouch)


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## Varley (Oct 1, 2006)

I am not sure about polishing. Aren't we actually de-glazing the surface as the luboil will not cling evenly to a 'glass' (polished) finish. Experts, please?


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## Duncan112 (Dec 28, 2006)

Yes Dave, deglazing is the term, for the reasons you describe accomplished by a variety of methods, emery paper, hand held carborundum stone, something like a crazed toilet brush with stones on the ends of the bristles on the end of a drill, or for the really affluent a Chris-~Marin device with vertically mounted stones. 


Engines that spent long periods at low load appeared to be more prone to glazing - I assume the oil company selected it's trial engine very carefully for load profile and optimum results. 

Bit about it here on smaller engines - I'm not sure however tipping Vim into the inlet is a good idea probably makes work for the website engineer who mentions it Bit about it here - I'm not sure however tipping Vim into the inlet is a good idea http://coxengineering.sharepoint.com/Pages/Boreglazing.aspx


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## uisdean mor (Sep 4, 2008)

Duncan112 said:


> Yes Dave, deglazing is the term, for the reasons you describe accomplished by a variety of methods, emery paper, hand held carborundum stone, something like a crazed toilet brush with stones on the ends of the bristles on the end of a drill, or for the really affluent a Chris-~Marin device with vertically mounted stones.
> 
> 
> Engines that spent long periods at low load appeared to be more prone to glazing - I assume the oil company selected it's trial engine very carefully for load profile and optimum results.
> ...


Aye Duncan , An additional reason/need to deglaze was to start to take actual wear rates on the liners esp the medium speeds. There was a move at one time to bunker type fuel and lots of hassle followed. Most switched back to a mix of low residue lighter fuels to reduce the wear rates and thereby extend routine maintenance timings. A balance between fuel cost savings, downtime and spares costs. There are a couple of threads on here regarding the abnormal wear that the heavier fuels had on the exhaust valves. Slainte 
UM


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## makko (Jul 20, 2006)

Yes, Deglazing. Honing of the liners leaves a criss cross pattern. The irregular, i.e. not smooth, surface allows the lube oil to adhere and form a surface film - Too smooth, no surface film = excessive wear. I attache a picture of a cylinder liner from a Wartsila 46V18.
Rgds.
Dave


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## BLACKMIRRLEES (May 1, 2014)

Thank-you for the replies so far. I was reading a report where it was believed that the sulphurous and sulphuric acid formed during the combustion process of higher sulphur content fuels, actually scavenged the lacquering from the cross- hatch grooves, and that with regulations demanding significant reductions in the sulphur content between now and 2020, the problem of liner lacquering would increase as the sulphur content falls. This report was around 2007, and that is why I am asking this question seven years on with lower sulphur fuels being increasingly used.


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## Duncan112 (Dec 28, 2006)

For many years now FOBAS and DNV fuel analysis reports have carried the rider about "Fuel has reduced sulphur content and cylinder lubrication should be adjusted accordingly" - I always assumed it was to do with the TBN of the oil being too high and causing caustic corrosion problems - now I know different - thanks. 

Was there not a test for used stuffing box oil that measured the TBN on board?


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## makko (Jul 20, 2006)

The sulphur in the fuel acts as a cylinder lubricant. When low sulphur fuels started to be used, there were a lot of problems with cylinder seizure. Newer engines have a variety of schemes to ensure that there is sufficient lubrication to the running parts in order to avoid any problems. 
Rgds.
Dave


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