The 997's 3.8 is known for scoring its cylinder bores — almost always cylinders 5 and 6 — and a dealer's answer is a five-figure engine swap. Caught early, the real fix is a sleeve and piston repair, and we run the whole job from your home.
The 997's 3.8 uses Lokasil/Nikasil-type coated aluminum bores instead of iron liners. Cylinders 5 and 6 sit at the bottom rear of the flat-six where they run hottest and get the least generous oiling, and over time the piston skirt starts wearing through the bore coating. Once the coating breaks down, aluminum runs on aluminum, and the bore scores — vertical scratches you can eventually hear as a distinctive cold ticking from the driver's side of the car.
A scored bore stops sealing. Compression on that bank drops, oil gets past the rings and burns as grey smoke on start-up, and combustion gases start pushing into the cooling system, which is why coolant level slowly falls with no visible leak. A compression and leak-down test pinpoints it fast, and a borescope through the plug hole confirms it visually — you can see the score marks.
Caught early, this does not need a new engine. The repair is to pull the engine, machine the damaged cylinder for an iron or Nikasil sleeve, and fit a new piston — restoring the bore better than factory. Left too long, the scoring spreads, the piston skirt collapses, and you're into a full rebuild or replacement engine, which is how dealers arrive at $12,000–$18,000 quotes.
If your Porsche is doing any of these, this is the likely cause:
Bore scoring only travels in one direction. Early on, it's one or two cylinders that can be sleeved while the rest of the engine is healthy. Keep driving on it and the score deepens, the piston skirt hammers itself apart, debris circulates through the engine, and combustion gas pressurizes the cooling system until it overheats. At that point a targeted sleeve repair becomes a complete engine — the difference between a repairable problem and a car-totalling one is usually a few thousand kilometres.
The engine removal, rebuild, and reinstall happen at your home — the precision machining of the cylinder itself is done at a specialist machine shop, because that requires fixed equipment nobody can bring to a driveway. So it's a two-visit job with the machining in between, and your 911 never leaves your property.
Because dealers don't repair scored bores — they replace engines. A replacement or factory-rebuilt flat-six plus installation is how you get to $12,000–$18,000. A sleeve-and-piston repair fixes the actual damaged cylinder for far less work and parts. We give you one flat quote for the complete repair before anything is taken apart.
Diagnosis comes first, always. A cold-engine listen, a compression and leak-down test, and a borescope through the spark plug holes will either show the score marks or rule them out. Plenty of 997 ticks turn out to be lifters or exhaust leaks — we confirm before anyone talks about pulling an engine.
A properly machined iron or Nikasil sleeve with a new piston is, if anything, tougher than the original coated aluminum bore — it's the same approach the well-known Porsche engine rebuilders use. The repaired cylinder ends up more score-resistant than the factory one.
Send it over for a free second opinion. I'll tell you straight what the job actually involves — and if their quote is fair, I'll tell you that too.
Get a Free Second OpinionOther makes:
Describe it to the AI mechanic (bottom right), or get a flat quote for the complete job. We come to you, anywhere in the GTA.
Call/Text 647-450-0406 Get a Flat Quote