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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHCrosshatched clyinder wall or bore scoring
Leading reported evidence
Replace almost all of the v8 engines once or
Performed · outcome unconfirmed
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0
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0
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1
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Read evidence and context
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Performed · outcome unconfirmed
They ended up replacing almost all of the V8 engines once or twice..
Leading evidence: 'Replace almost all of the v8 engines once or' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace almost all of the v8 engines once or' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
My best advice just keep changing the oil and monitor that filter.
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Suggestion
If this was recently purchased, if I had to guess - there was an issue with the rings on bank-2 and a mechanic took it apart, honed the bores, cleaned up or replaced the pistons, and then reassembled it (we don't know what other steps were taken).
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Suggestion
as if they were just cleaned up and run for a few hours.
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Suggestion
If this was recently purchased, if I had to guess - there was an issue with the rings on bank-2 and a mechanic took it apart, honed the bores, cleaned up or replaced the pistons, and then reassembled it (we don't know what other steps were taken).
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15 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
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Hello,
Guys I need your help to identify if the following clyinder wall scratches is bore scoring
This is for
cayman 987.1
2006 mileage 35k
Bank 2 driver side
I am confused with the crosshatch pattern vs normal vertical lines. No white smoke and oil consumption is normal. Added liqui molly ceratech with my oil change
But Bank 1 passenger side looking clean
Hi,
Thank you for your insights. Given your experience, would you advise that a sleeve job is necessary at this stage, or are there any interim measures you might recommend?
I would like to know exactly how that cross hatch came about. Clearly it may have been applied to reduce the bore score underlying in the cylinder wall. Do you know the history as the cross hatch does not occur without machining and only 3 cylinders.
I do not believe there should be any cross hatching.
Here is a picture
stolen from ******** about bore scoring. Notice there is no cross hatching. I am not an expert so I can't speak on authority. Just google 'M96 bore scoring' or 'M96 cylinder', let me know if you find any with cross hatching.
If I had to guess; someone had bore scoring. Then some 'mechanic' took it apart, honed it, reringed it, and hoped for the best.
The crosshatch is from the factory. It's the final finishing and sizing step on the cylinder bores. The material is alusil - which is an aluminum block with silica embedded in it. The cylinders are bored, then honed with an acid mixture that etches away a tiny bit of the aluminum, leaving the very hard silica particles exposed, and they are what the piston slides in and the rings slide against.
BMW
used this on a number of motorcycles - and it wasn't unusual at all to see the crosshatch still intact at well over 200,000 miles (they also used it with less success on their late 1970's V8 engines, where high sulfur content in US fuel combined with moisture produced by combustion to create sulfuric-acid in the cylinders - not conducive to long life of that sort of bore. They ended up replacing almost all of the V8 engines once or twice.. finally went to a different bore/block process.)
Really rather a mystery why one bank shows the crosshatch and the other doesn't. I'll be really interested in what scoping it from underneath the pistons shows..
@Vortex Ring State
may be onto something..
Agree, the main question; why bank2 is different and cross-hatched.
Here is a video link of bank 1 without cross-hatching
VID-20240127-WA0074.mp4
i don't have video for bank 2, only photos. I will try to scope from the bottom and will post it
Sometimes bore scoring won’t worsen (so to speak) because there has been a natural tolerance that occurred over time.. those vertical lines are light gouges… if it’s not using oil and not misfiring I’d just run it… you know what a motor costs right? My best advice just keep changing the oil and monitor that filter. Cut it open..
@Mazen
- was this a recently purchased vehicle? The reason I asked - the piston crowns are remarkably clean.. as if they were just cleaned up and run for a few hours. If this was recently purchased, if I had to guess - there was an issue with the rings on bank-2 and a mechanic took it apart, honed the bores, cleaned up or replaced the pistons, and then reassembled it (we don't know what other steps were taken).
A second reason I'd suspect this - the crosshatch is on top of the bore scoring. It's pretty obvious if you look at it carefully. That can only happen if the scratches were there first and someone came along with a hone and honed it down.
