Porsche bore scoring: diagnosis

The inspection

Oil consumption, smoke, and cold-start knocking can point to bore scoring, but they do not confirm it.

It is performed using an endoscope inserted through the spark plug hole while the engine is still in the car. Within a morning, we can determine if scoring is present, which cylinders are affected, and the extent of the damage. We always recommend this check before a purchase: it makes the difference between negotiating the price upfront and discovering the issue later.

The price is listed in our rate schedule, alongside other services for the model.

Sleeved cylinder bores of an M97 engine block, with the honing crosshatch visible

Confirm before rebuilding

bore scoring must be confirmed with evidence before attributing noise, oil consumption, or smoke to the need for an engine rebuild.

Six-cylinder endoscopy.
Photographs.
Oil and filter analysis and.
Where applicable.
Compression tests.
Leak-down tests.

Three cylinder bores of an M97 block seen from the cylinder head face

Engines covered and report findings

The diagnosis specifically targets M96 and M97 engines in Boxster, Cayman, and 911 models manufactured between 1997 and 2008, with the repair determined by the damage found.

A superficial mark, active scoring, and loss of compression do not call for the same decision. The report allows for comparing monitoring, honing, and rebuilding.

Close-up of a finished sleeved bore, beside the block's threaded hole

Endoscopy without disassembly; sleeving if necessary

We diagnose cylinder liner scoring via endoscopy—without dismantling the engine—and repair it by re-sleeving once the damage has occurred. This inspection is a fixed-price service and the first step we recommend before purchasing an M96 or M97.

bore scoring affects Boxster, Cayman, and 911 models with M96 and M97 engines manufactured between 1997 and 2008. It manifests as vertical scoring on the cylinder wall—most frequently in the sixth cylinder—and progresses until the engine consumes oil and loses compression.

The repair

When scoring is present, the solution is not to re-bore, but to replace the cylinder liner. We install liners made of a nickel-silicon-carbide alloy—which is harder than the original Lokasil—and take the opportunity to inspect the rest of the engine block, since it is already open.

For many engines, if the block is being opened anyway, it makes sense to increase the displacement during the same procedure: a M97 3.8 can be upgraded to a 4.0 with no additional labor cost, as the work is already being performed.

What is included

Endoscopic inspection of all six cylinders and assessment of scoring.
Oil and filter analysis.
Compression and leak-down test.
Report with photographs of each cylinder.
Repair quote, if applicable, before any work begins.

bore scoring assessment, based on the images.

The magazine showcases the work and photos in this documented case study.

Inside of a cylinder with the vertical bore scoring marks on the wall

What you get from the check

Images of each cylinder, an easy-to-understand assessment, and—if applicable—a quote for cylinder sleeving and block inspection before any engine work is performed.

Related services

Depending on the car's condition and intended use, the work can be coordinated with a pre-purchase inspection, engine rebuild, or workshop rates.

Frequently asked questions

01 Does an endoscopy mean repairs are mandatory?

No. Its purpose is to show the current condition. Recommendations depend on the depth and extent of the scoring, symptoms, and the results of other tests.

02 Is it worth inspecting before buying?

Yes, for the affected model families. The result helps decide whether to proceed, negotiate the price, or set aside a budget for repairs.

See it done

Jobs documented in the Magazine, with photos of the process.

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