We have recently come across with burning marks as per the attached photo on the combustion surface of M/E piston crowns. Has anybody seen this before? What could be the root cause?
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Hello to all. As it can be seen the piston crown has developed the so called elephant skin. This type of wear can be related with high combustion temperatures and it is usual when the engine is operating constantly under low load. When slow steaming the engine’s T/C(s) are not able to build up sufficient scavenge pressure (blowers in operation) leading to higher combustion temperatures and higher exhaust gases temperatures.
In these cases it is recommended the engine load to be increased to high load (more than 55% every 48 hours of operation). Most T/C makers suggest the same.
In addition and in regards to the redish coloring, if this is not coming from dye check compound then it can be related with wear of the M/E air cooler tubes (copper).
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Very useful insight @Dim ! Thank you
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very useful indeed @Dim .
Would you consider the same case for below? piston crown has about 30.000 hrs.
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I have encountered the orange colour pigmentation on cylinder liner where the liner was worn out to max limit. We didn’t have space liner we need to cut out one unit untill we reached safely to next port where liner was renewed. If this orange colour pigmentation is seen, soon 
the Unit liner will be worn to maximum. Make sure you when this is noticed to have spare liner & necessary spare for overhauling of liner.
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Hi! @Spyros.P apologies for my late reply.
Are these burning marks located just under the Fuel Injectors?
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Good morning @Dim , if I remember correctly ,for this particular piston crown the marks are at the pump side and exhaust side (stbd & port side )
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Hello @Surcouf_Renard!
I am interested in this topic. Have you finally had any updates or reached conclusions on it?
Good day and season’s Greetings to all!
Since that the observed wear ist located in an area far from the fuel injectors (if we are talking for a 2 fuel a injector equipped engine of course) the root cause should be investigated for other factors. Such as Cylinder Liner & piston skirt level of wear. There is a possibility of Cylinder’s (the whole Piston,X-Head- Piston Rod, Connecting Rod assembly) misalignment due to increased cylinder liner or skirt wear, causing also the uneven wear of the Piston Crown from the impact on the Cylinder Liner wall during Engine’s rotation.
In addition the Cylinder’s PCR (Piston Cleaning Ring) may be suspected as well. Wrong positioning after overhauls or omission of replacement during liner replacement may leed to similar wear followed of course from a metallic sound during engine operation.
There many contributing factors for Cylinder Condition issues.
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Hello @NikosPiperis We have engaged M/E makers in this investigation. It appears that the root causes were the combination of low load and faulty M/E fuel oil injectors.