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Read the WELCOME ALL BMWFANATICS post.
The ominous signs of the end of times (for the 323i, that is)
- Thread starter Ricky318i
- Start date
Philip Foglar
///Member
Hmm, did they indicate why this was the case?
Iceman007
Active member
This is what I found
http://www.tpub.com/content/engine/14076/css/14076_56.htm
SCORED CYLINDER LINERS Scored cylinder liners may become scored (scratched) by several means. These scratches degrade the engine’s performance and require some type of repair. Scored cylinder liners may be caused by broken piston rings, a defective piston, improper cooling, improper lubrication, or the presence of foreign particles or objects. Dust particles drawn into an engine cylinder will mix with the oil and become an effective but undesirable lapping compound that may cause extensive damage. The importance of keeping the intake air clean cannot be overemphasized. Another precaution you should take is to make sure that when you replace a cylinder head, you leave no metal chips, nuts, bolts, screws, or tools in the cylinder. Causes Scoring may be in the form of deep or shallow scratches in the liner surface. With most liner scoring, there will be corresponding scratches on the piston and piston rings. The symptoms of scoring may be low firing or compression pressure and rapid wear of piston rings. The best method for detecting scoring is visual inspection through liner ports, through the crankcase housing with pistons in their top position, or when the engine is disassembled. Badly worn pistons and rings may cause scoring because blowby of combustion gases increases the temperature of the liner and may reduce the oil film until metal-to-metal contact takes place. Inspect the pistons and rings carefully. A piston with a rough surface (such as one that has seized) will score the liner. Scoring as a result of insufficient lubrication or dirt in the lubricating oil can be prevented if lubricating equipment (filters, strainers, and centrifuges) is maintained properly. Lube oil must be purified according to required procedures. Repairs Ship’s force personnel normally do not repair scored liners; they replace them with spare liners. When necessary, liners with minor scoring may be kept in service, if the cause of scoring is eliminated and the minor defects can be corrected. The surface of the liner must be inspected carefully, especially in the region next to the ports, for any burrs, projections, or sharp edges that will interfere with piston and ring travel. Most projections can be removed by handstoning, using a fine stone. Figure 3-4 shows a liner before and after the ports were stoned. EXCESSIVELY WORN LINERS Over a period of time, cylinder liners become worn simply because of engine operation. The best method of finding excessive wear is to take measurements of the cylinder liner with an inside micrometer caliper. Two 3-4
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Best matches for Engine causes of barrel scratches and score marks
These scratches degrade the engine's performance and require some type of repair. Scored cylinder liners may be caused by broken piston rings,
Since these engines start using oil from New its Defanitave Manufacturing Defect :thumbdo:
Several conditions can cause a bore to become scored. Dirt or debris may have entered the cylinder as the engine was operating. This happens frequently if an engine is operated with no air filter. Without a filter, dirt can easily penetrate an engine through its carburetor, and from there work its way into the combustion chamber. It is possible for dirt to become lodged between the piston and bore. As the piston travels up and down, this dirt will scrape the bore, leaving score marks.
Another common cause of score marks is improper engine lubrication. The cylinder wall must be coated with a film of oil to allow the piston and rings to move freely. In many small four stroke engines, oil is flung from the crankcase onto the cylinder walls by an oil slinger or similar distribution device. In small two stroke engines, oil is normally mixed directly into the fuel. For whatever reason, if there is a problem with an oil distribution system, oil may not reach the cylinder walls. If the bore is dry, friction between it and the piston may score the cylinder wall, and possibly the piston skirt.
Score marks in a bore can also be caused by overheating. If an engine is run at extremely high temperatures, oil on the cylinder wall will not afford enough lubrication for the piston and rings. At excessively high temperatures, oil may also break down and lose its properties, leaving behind score marks.
Score marks found on the cylinder wall should always be removed before an engine is reassembled. If marks are small, they can be removed during routine reconditioning. If the marks are deep, removing them is more problematic; it may enlarge the bore too much for use with a standard sized piston. For this reason, larger pistons, referred to as oversize pistons, are available. With an oversize piston, the combustion chamber will seal properly even if its bore was enlarged to remove deep score marks. Before enlarging the cylinder, you must determine if oversize pistons are available for that engine, and what sizes they are offered in. Once the size of the larger replacement piston is known, the bore can be enlarged to match. There is a limit to how much a bore can be enlarged. In an engine service manual, the manufacturer will specify how much a specific cylinder can be enlarged.
I realy think they already know what the problem is but as we know they will never admit it in public. To much money involved. Thats why I would like to see how your new engine is doing for Maybe they fixed the manufacturing defect :idea:
http://www.tpub.com/content/engine/14076/css/14076_56.htm
SCORED CYLINDER LINERS Scored cylinder liners may become scored (scratched) by several means. These scratches degrade the engine’s performance and require some type of repair. Scored cylinder liners may be caused by broken piston rings, a defective piston, improper cooling, improper lubrication, or the presence of foreign particles or objects. Dust particles drawn into an engine cylinder will mix with the oil and become an effective but undesirable lapping compound that may cause extensive damage. The importance of keeping the intake air clean cannot be overemphasized. Another precaution you should take is to make sure that when you replace a cylinder head, you leave no metal chips, nuts, bolts, screws, or tools in the cylinder. Causes Scoring may be in the form of deep or shallow scratches in the liner surface. With most liner scoring, there will be corresponding scratches on the piston and piston rings. The symptoms of scoring may be low firing or compression pressure and rapid wear of piston rings. The best method for detecting scoring is visual inspection through liner ports, through the crankcase housing with pistons in their top position, or when the engine is disassembled. Badly worn pistons and rings may cause scoring because blowby of combustion gases increases the temperature of the liner and may reduce the oil film until metal-to-metal contact takes place. Inspect the pistons and rings carefully. A piston with a rough surface (such as one that has seized) will score the liner. Scoring as a result of insufficient lubrication or dirt in the lubricating oil can be prevented if lubricating equipment (filters, strainers, and centrifuges) is maintained properly. Lube oil must be purified according to required procedures. Repairs Ship’s force personnel normally do not repair scored liners; they replace them with spare liners. When necessary, liners with minor scoring may be kept in service, if the cause of scoring is eliminated and the minor defects can be corrected. The surface of the liner must be inspected carefully, especially in the region next to the ports, for any burrs, projections, or sharp edges that will interfere with piston and ring travel. Most projections can be removed by handstoning, using a fine stone. Figure 3-4 shows a liner before and after the ports were stoned. EXCESSIVELY WORN LINERS Over a period of time, cylinder liners become worn simply because of engine operation. The best method of finding excessive wear is to take measurements of the cylinder liner with an inside micrometer caliper. Two 3-4
Privacy Statement - Press Release - Copyright Information. - Contact Us - Support Integrated Publishing
Best matches for Engine causes of barrel scratches and score marks
These scratches degrade the engine's performance and require some type of repair. Scored cylinder liners may be caused by broken piston rings,
Since these engines start using oil from New its Defanitave Manufacturing Defect :thumbdo:
Several conditions can cause a bore to become scored. Dirt or debris may have entered the cylinder as the engine was operating. This happens frequently if an engine is operated with no air filter. Without a filter, dirt can easily penetrate an engine through its carburetor, and from there work its way into the combustion chamber. It is possible for dirt to become lodged between the piston and bore. As the piston travels up and down, this dirt will scrape the bore, leaving score marks.
Another common cause of score marks is improper engine lubrication. The cylinder wall must be coated with a film of oil to allow the piston and rings to move freely. In many small four stroke engines, oil is flung from the crankcase onto the cylinder walls by an oil slinger or similar distribution device. In small two stroke engines, oil is normally mixed directly into the fuel. For whatever reason, if there is a problem with an oil distribution system, oil may not reach the cylinder walls. If the bore is dry, friction between it and the piston may score the cylinder wall, and possibly the piston skirt.
Score marks in a bore can also be caused by overheating. If an engine is run at extremely high temperatures, oil on the cylinder wall will not afford enough lubrication for the piston and rings. At excessively high temperatures, oil may also break down and lose its properties, leaving behind score marks.
Score marks found on the cylinder wall should always be removed before an engine is reassembled. If marks are small, they can be removed during routine reconditioning. If the marks are deep, removing them is more problematic; it may enlarge the bore too much for use with a standard sized piston. For this reason, larger pistons, referred to as oversize pistons, are available. With an oversize piston, the combustion chamber will seal properly even if its bore was enlarged to remove deep score marks. Before enlarging the cylinder, you must determine if oversize pistons are available for that engine, and what sizes they are offered in. Once the size of the larger replacement piston is known, the bore can be enlarged to match. There is a limit to how much a bore can be enlarged. In an engine service manual, the manufacturer will specify how much a specific cylinder can be enlarged.
I realy think they already know what the problem is but as we know they will never admit it in public. To much money involved. Thats why I would like to see how your new engine is doing for Maybe they fixed the manufacturing defect :idea: