In 3200HP diesel engine we have recurrent failure of cylinder liners. They fracture in the angle between the body and the settlement zone. We think the failure is related with deformations in the settlement zone in the engine block so we will grind this surface and also the upper part of the bore in the block. Does anybody have known this kind of failures and its causes?.
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Cylinder liner fracture 1
- Thread starter jeromero
- Start date
ElwoodGreen
Mechanical
What type of service? If standby power generation, then maybe you have a thermal shock type of problem when you ask the cold engine to produce full power within too short of a time period. Some folks crack a lot of heads and other components that way.
If you have too much piston skirt to bore clearance, I suppose the piston could be knocking too hard against the lower section of the bore when it changes direction after BDC.
We haven't had that problem, yet, so these were just a couple of thoughts.
If you have too much piston skirt to bore clearance, I suppose the piston could be knocking too hard against the lower section of the bore when it changes direction after BDC.
We haven't had that problem, yet, so these were just a couple of thoughts.
- Thread starter
- #3
Thank you for your soon answer. The application is continuous electrical power generation (2 MWH), the failures have hapenned in normal operation. We have cooling water temperature monitoring and and in the failures we don't see big changes in temperature. Only once (a years ago) we had a fracture caused by thermal shock. Now is different, in normal operation we have had nine (9) liners broken in last year. I have asked for this problem and most people affirm the problem is associated with block distortion. We grind the surfaces manually and measure the distance between OD of the liner and the lower part of the block and guarantee the liner is centered, but the problem persists. So now we will grind the surface with machines and hope to solve the problem.
jeromero:
What engine is this?
Could post some pictures or a drawing of the problem with some details of liner thickness etc etc.
Are they wet or dry sleeve arrangement etc.
How are the liners being finished to size,when installed or other.
Is there any other obvious problems associated with this, piston scoring etc etc.
Do you know what grade the sleeve material is ?
Is it the same sleeve failing.?
Do the big end bearings or the small ends show any signs of premature wear along with the sleeve failures?
Is the engine operating under full load conditions all the time or does it vary.?
What engine is this?
Could post some pictures or a drawing of the problem with some details of liner thickness etc etc.
Are they wet or dry sleeve arrangement etc.
How are the liners being finished to size,when installed or other.
Is there any other obvious problems associated with this, piston scoring etc etc.
Do you know what grade the sleeve material is ?
Is it the same sleeve failing.?
Do the big end bearings or the small ends show any signs of premature wear along with the sleeve failures?
Is the engine operating under full load conditions all the time or does it vary.?
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- #5
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- #7
Yes this is the same cylinder. Somebody can think that the leaks were through the cylinder liner cracks, but even with new liner we had low compression pressure. We are investigating if both phenomena are related. Actually we have the same thermodynamic condition in other cylinders and in other units, obviously we are afraid to have more broken liners.
The engine is mounted on conventional foam, like in most constructions.
The engine is mounted on conventional foam, like in most constructions.
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- #8
enginesrus
Mechanical
Body and settlement zone?????
Upper area?
Lower area?
Sounds like liner clearance is excessive, and or piston loading?
Upper area?
Lower area?
Sounds like liner clearance is excessive, and or piston loading?
- Thread starter
- #9
enginesrus
Mechanical
How many hours on these engines?
The best fix for the counter bore area is to sleeve it.
Also check manufactures spec on diameters of both upper and lower bores in the block.
The best fix for the counter bore area is to sleeve it.
Also check manufactures spec on diameters of both upper and lower bores in the block.
- Thread starter
- #11
- Thread starter
- #12
Chris-marine also recommended us to install an L-ring in the block and machine it to the original dimensions.
Another question, in the upper zone of the bore according to the manufacturer specifications we have a clearance between 7 and 12 mils in diameter. Making a calculation of thermal expansion of the liner it would expand around 13 mils. In the engine design the liner could be "tight"in this zone???. It is important because we want to know if it is possible to install an "oversize" liner (a liner with a bigger diameter in the upper zone of the bore in the block).
Another question, in the upper zone of the bore according to the manufacturer specifications we have a clearance between 7 and 12 mils in diameter. Making a calculation of thermal expansion of the liner it would expand around 13 mils. In the engine design the liner could be "tight"in this zone???. It is important because we want to know if it is possible to install an "oversize" liner (a liner with a bigger diameter in the upper zone of the bore in the block).
enginesrus
Mechanical
L-ring,,,sleeve same thing. That is what I meant.
Everything expands together. That is the block will expand too.
Have never experimented with it. But I have never liked the idea of any liner clearance. Allows for too much loading and vibration, and helps contribute to cavitation pitting on the lower portion of the liner and the block. Dry liners are pretty much zero clearance, semi press fit. And never seems to be an expansion or cracking problem.
If it is possible to install the L-ring. Then it should also be possible to bore that portion of the cylinder block to accept the larger liners. Of course maintain the manufactures recommended clearances. I would guess the cracking problem is from excessive clearances, that would cause loading due to that calculated thermal stress, and or a vibratory situation, make sure all the manufactures dimensions are checked for all areas that the liner locates in.
Everything expands together. That is the block will expand too.
Have never experimented with it. But I have never liked the idea of any liner clearance. Allows for too much loading and vibration, and helps contribute to cavitation pitting on the lower portion of the liner and the block. Dry liners are pretty much zero clearance, semi press fit. And never seems to be an expansion or cracking problem.
If it is possible to install the L-ring. Then it should also be possible to bore that portion of the cylinder block to accept the larger liners. Of course maintain the manufactures recommended clearances. I would guess the cracking problem is from excessive clearances, that would cause loading due to that calculated thermal stress, and or a vibratory situation, make sure all the manufactures dimensions are checked for all areas that the liner locates in.
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