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Was diagnosed by BMW main dealer cylinder 7 piston ring failure and no compression in cylinder 7, others seems fine. I know it's major task but in this case it's only 28000 miles so it's not that all engine worn out. Car was ECU tuned to 680bhp. I'm just thinking what parts most likely need to replace only piston ring or something else. Car is not much driven after this maybe 10 miles. I know if it was wear and tear it would be huge job and many parts need replacing. But this car is low mileage and I think other pistons and cylinders are fine. Of course tomorrow I go to mechanic independent specialist but today got offer to sell but for very low price just thinking if this could be few thousand job like 2-3 thousands or any case 10000+ job...?
 

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Ok but you think it's not cheaper if only one cylinder fail only one piston ring need changed and other parts 99% should be fine
 

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Before you do anything, get that second opinion from an independent shop that you mentioned. I would have them confirm no compression and then scope the cylinder to look for damage to the cylinder wall. If the wall is scored, you're probably better off using that engine as a core to a rebuilder and buying a new rebuilt replacement. If the wall looks clean, than set of rings could probably be replaced and put back together but I don't know the nuances of these engines to know for sure. You might want to figure out what caused the failure too. Either way, the entire engine should be torn down and cleaned because the broken ring pieces/metal are spread throughout the engine now.
 

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If your planning on doing the work yourself it will cost you around 3000 if everything else is still intact. High chance that the wall is scored and will need a sleeve for that cylinder. If your going to push the engine and get it hot you will need better rings with a larger gap.
 

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Was diagnosed by BMW main dealer cylinder 7 piston ring failure and no compression in cylinder 7, others seems fine. I know it's major task but in this case it's only 28000 miles so it's not that all engine worn out. Car was ECU tuned to 680bhp. I'm just thinking what parts most likely need to replace only piston ring or something else. Car is not much driven after this maybe 10 miles. I know if it was wear and tear it would be huge job and many parts need replacing. But this car is low mileage and I think other pistons and cylinders are fine. Of course tomorrow I go to mechanic independent specialist but today got offer to sell but for very low price just thinking if this could be few thousand job like 2-3 thousands or any case 10000+ job...?

I'd approach your ECU tuner first....
 

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I would recommend strongly against any kind of partial rebuild, as they never turn out well. S63 rebuilds can be done reasonably inexpensively. Raza at RK Autowerks in Dallas does them quite efficiently. We probably will start doing them ourselves in the next 12-18 months.

--Peter
 

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Its never just a few thousand, throwing that number out there is nothing different than trying to hit a powerball. Its close to 30 hours labor just to do the engine job, there goes your 3k fix. This will without any doubt be over 10k regardless where you go. An independent shop will give you a great deal to pull it all apart to get you in the door. Then will tell you its that same 10k+ job.

At which point you will probably realize its not really worth it because you went in without realistic expectations and under budget, except at that point your cars engine will be in the trunk and worth even less...at least now it runs...sort of. If you dont realistically feel content with spending 10kish on fixing it, let it go.

Heck tuned to 600+. You got a chunk of ring land missing and probably cylinder gone with it. Downright Zero compression on " worn " rings doesn't happen.

Heck i'll buy it if price is right. Drop your contact.
 
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