Cylinder Bore (Scoring)



1 – Repairable without Reconstruction
 – Engine Reconstruction Required




– A noise that “sounds like a lifter” (often misdiagnosed!)

-The noise will have the same rhythm and tone as a typical hydraulic lifter issue

-One tailpipe more sooty than the other(this is often thought to be related the the failure occurrence, but it actually is a symptom of the equation that creates this failure!)

-Sooty tailpipes are more common on the driver’s side of 996/997 cars

-Increased oil consumption (at advanced stages of failure only)

-Misfires logged, P0300 DTCs are common at advanced stages only


Wear debris from the scored bores is very hard, and abrasive. Engines operated with scored cylinder bores will suffer multitudes of collateral damages due to this wear debris being suspended in the engine’s oil supply, and being circuilated to all internal components.

As the cylinders lose ring seal, due to the bore scoring, harmful fuel contaminates the oil as it bypasses the piston rings. This fuel enters the engine oil, thus reducing oil viscosity as it intrudes into the oil.

This fuel contaminated oil then loses it’s ability to protect the engine components, further increasing wear throughout the engine, as well as the cylinders.


Diagnosis of this failure often begins with tests using an “electronic ear”. Listening for the root of the noises the engine is making will clearly define this issue to those with an experienced, trained ear. Those that lack extensive, direct experience with the M96/97 engines may still believe this is a failure of a valve lifter. Trust that it is not in 95% of the cases we have seen first- hand.

Often times shops less than experienced with this failure will choose visual “bore scope” procedures to view the “scoring”. Note that this method only works in advanced cases, (stage 3 &4 failure) where scoring has traveled further up the bore, and can be seen. In early stages, the scoring starts at the bottom of the cylinders, and is covered up by the piston while positioned at “BDC” for the visual inspection to be carried out. This often fools those that perform this test, as they see nothing wrong. Typically, since no scoring is visible, it supports the aforementioned narrative that the failure is a “lifter”. It is often at this time that thousands of dollars become wasted, performing a “lifter job” that does not address the issues at all.

In other cases the general shop will often perform “leakdown” and “compression” tests in hopes of gaining more data to support the reasons of why the engine is making noise, and consuming oil. These will more than likely show nothing is wrong with the engine! Why? Because the cylinders that are failing often have oil enter the rings and cylinders in excess amounts, and this oil will act to “seal” the cylinder better. This fools the diagnostician that lacks direct experience with this failure, as it is counterintuitive. Why would a cylinder that’s having issues test better than the others? As we say “they don’t teach that at Porsche school, or at Wyotech!

All this being said, normally shops do these tests for no other reason than to remove money from your wallet. Save that money, and put it toward a Flat 6 Innovations engine reconstruction.

We have developed a specific (very unconventional) regimen to diagnose these issues, and share them in our hands- on training classes offered by


Engines suffering scored bores must be properly reconstructed. Wise purchasers will choose our services, taking advantage of our developmental work with LN Engineering’s “Nickies” cylinder line. As LN’s first customers, dating back to 1999, we have been instrumental in the development of this cylinder technology. No one in the world has used more “Nickies” than Flat 6 Innovations.

LN’s “Nickies” are not a band aid. All 6 cylinders of the engine are machined away and fitted with billet alumunim cylinders that are then Nikisil plated, like those of the famed Mezger aircooled engines. Nikisil is comprised of Nickel, Silicon, and Carbide. These are all hard, wear resistant materials that are plated onto the cylinder wear surfaces. These are not coatings! Don’t be fooled!

Some less- than- adequate “low cost” alternatives are things you will run across as you search this failure mode more, and more. Never use a steel sleeve to repair this issue, as the expansion coefficients are incorrect, the engine will always be noisy, and will likely have more issues than the process solved. This isn’t a Chevy, its a Porsche, and it doesn’t deserve to be compromised with an iron/ steel sleeve.

100% of our engines have used LN “Nickies” since the beginning of our program. We will not perform reconstruction any other way. You should not either.

Jake Raby Explains “Bore Scoring 101”

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