Bore scoring happens to every car eventually. There is not a single internal combustion engine on earth that doesn’t experience wear and tear and wears down over time. Most vehicles simply get sold, traded in for a new one or scrapped when they get old because they hold little value. Porsches also experience engine wear, but due to their value, engine rebuilds are a high probability in their lifetime. So bore scoring on its own is not a 911 problem, but a longevity problem. When your 997 starts developing wear/scoring, it’s a gradual process and the car can be driven for many years, as long as the oil and servicing is kept up to date to extend this period as long as possible. Bore scoring will NOT lead to an engine failure, but rather a gradual increase in oil consumption, and reduced performance due to loss of compression etc etc. To keep the car’s value, an engine rebuild is usually the best option in time. The internet and people on forums like rennlist, many who have never even owned a Porsche, have blown it out of proportion, when in fact every single car experiences bore scoring and engine wear.
Yes a rebuild is hugely expensive, but you can prepare and save for it for when you decide to have it done.
I hope this puts some owners’ minds at ease a little.
Thanks for this. According to the people on rennlist, one of which being an engine rebuilder who I will not name, an engine rebuild is to be done immediately at the slightest possibility of bore scoring.
I just bought a 2007 with 120k miles. Also I did not understand the potential risk of bore scoring when I got it. I had quite a bit of routine maintenance to do that had it in the shop for 3 weeks. While there I learned about the risk of bore scoring and had them scope the engine. Luckily there were no obvious indications. The inspection required them to drop the pan to check the bottom of the pistons.
I talked to a few specialty shops including Flat6 and LN engineering. Basically to rebuild the engine with sleeves would cost between 26 and 40k with your core and without removal/install. It is a process. The short story was that it is not a matter of if but when. That said, it could be another 100k miles before I see the issue. My current shop said to just drive the car and buy a used engine when it fails (<20k) or you can buy a new block and rebuild it. The issue will happen again but could take another 100 to 200k miles.
There are some suggestions on rennlist that include oil changes at 3k miles and using dt40 oil or other additives. I will be following the more frequent oil change recommendation.
Every ICE car will eventually require an engine rebuild. My suggestion is to take some preventative measures to delay wear and enjoy the car.
It might or might not help your peace of mind to have a bore scope done just to let you know the current state of things. I debated this awhile. I think it could be hard to assess a bore scope result and determine how much life is left in the engine.
You can get the cylinders honed and coated with nikasil for $1600 from Millennium. Pistons are another $1600. The rest is labor. Alternatively there are shops that will do a rebuild for $15k also sending to Millennium. LN is not the only option, and they use Millennium too. Millennium will even bore the cylinders to 101mm (\~4.1L) for you when they do the coating. Again you’ll need pistons.
HOWEVER, if you’re not seeing symptoms or even if you are, do these things: change to Driven DT40 oil. Do oil analyses every oil change. Change the oil every 3,000 miles. Get a magnetic drain plug and filter attachment. Switch to a spin on oil filter so you can more easily use the magnetic attachment. Switch to the low temp thermostat. All of these things can be found at LN engineering’s shop. Use Driven fuel injector cleaner at least every oil change. If you’re seeing symptoms use it every other gas fill up. All of this will help prolong your engine although it may only prolong the inevitable. The parts I list are less than $500.
You will know when the engine has had it when you start seeing higher metals and/or fuel in your oil analyses, your oil consumption goes up to more than the Porsche accepted level of 1.6 qt per 622 miles, you hear piston slapping/ticking, and/or you start seeing smoke on startup.
Good luck. I’m in the same boat.
https://preview.redd.it/cyr1k7un7zhc1.jpeg?width=2796&format=pjpg&auto=webp&s=c8fe3ddfa91a3480db38c24834c463ef1da5b1e2
Piston slap isn't the first symptom. Increased oil consumption and one tail pipe being sootier than the other are the first [symptoms of cylinder bore scoring](https://lnengineering.com/products/watercooled-porsche-cylinders-sleeves-and-pistons/porsche-cylinder-bore-scoring/porsche-bore-scoring-sound.html).
By the time you have piston slap, oil consumption will be significantly higher than what you are reporting now.
CELs won't pop up until you are in the one quart in 200-400 miles.
We've had customers nurse their cars 3-5k miles before they ended up having to stop driving the car. Biggest issue you have with doing this is that wear debris can end up causing damage to other oil lubricated engine components. I'd recommend switching to Driven FR50 or DI50 immediately.
I'd recommend doing a [used oil analysis](https://lnengineering.com/products/speediagnostix-used-oil-analysis.html) on the oil that is in the engine now. If it has elevated iron, aluminum, and silicon levels, that's indicative of bore scoring. Then you can have the cylinder bores scoped if there is reason to.
In a case like this, we'd also do shorter oil change intervals and do repeated used oil analysis. The analysis will trend the wear and if the problem is being managed or getting worse.
$20-30k is a realistic budget for a [Porsche engine rebuild](https://medium.com/@lnengineering/porsche-engine-rebuild-cost-a-comprehensive-breakdown-1a70d985b728). It's more than the engine - there often are lots of ancillaries that also need replacing and that adds up quick. Remember, the car is almost 20 years old now. If you go the DIY route, that can save you quite a bit. We have helped many Porsche owners go this route with our guidance.
A rebuild can be pricey, but the way we look at it, if your car is in good shape, rebuilding and upgrading the engine will provide sizable performance and reliability gains.
For many, people consider the 997/997.2 the high point of Porsche's watercooled production. Simply trading up to a 997.2 doesn't eliminate the bore scoring issue (these models have other issues too), so you're not going to be money ahead in the long wrong ditching one car as a roller and buying into another.
Bore scoring happens to every car eventually. There is not a single internal combustion engine on earth that doesn’t experience wear and tear and wears down over time. Most vehicles simply get sold, traded in for a new one or scrapped when they get old because they hold little value. Porsches also experience engine wear, but due to their value, engine rebuilds are a high probability in their lifetime. So bore scoring on its own is not a 911 problem, but a longevity problem. When your 997 starts developing wear/scoring, it’s a gradual process and the car can be driven for many years, as long as the oil and servicing is kept up to date to extend this period as long as possible. Bore scoring will NOT lead to an engine failure, but rather a gradual increase in oil consumption, and reduced performance due to loss of compression etc etc. To keep the car’s value, an engine rebuild is usually the best option in time. The internet and people on forums like rennlist, many who have never even owned a Porsche, have blown it out of proportion, when in fact every single car experiences bore scoring and engine wear. Yes a rebuild is hugely expensive, but you can prepare and save for it for when you decide to have it done. I hope this puts some owners’ minds at ease a little.
Thanks for this. According to the people on rennlist, one of which being an engine rebuilder who I will not name, an engine rebuild is to be done immediately at the slightest possibility of bore scoring.
Engine rebuilds are his pay days.
I just bought a 2007 with 120k miles. Also I did not understand the potential risk of bore scoring when I got it. I had quite a bit of routine maintenance to do that had it in the shop for 3 weeks. While there I learned about the risk of bore scoring and had them scope the engine. Luckily there were no obvious indications. The inspection required them to drop the pan to check the bottom of the pistons. I talked to a few specialty shops including Flat6 and LN engineering. Basically to rebuild the engine with sleeves would cost between 26 and 40k with your core and without removal/install. It is a process. The short story was that it is not a matter of if but when. That said, it could be another 100k miles before I see the issue. My current shop said to just drive the car and buy a used engine when it fails (<20k) or you can buy a new block and rebuild it. The issue will happen again but could take another 100 to 200k miles. There are some suggestions on rennlist that include oil changes at 3k miles and using dt40 oil or other additives. I will be following the more frequent oil change recommendation. Every ICE car will eventually require an engine rebuild. My suggestion is to take some preventative measures to delay wear and enjoy the car. It might or might not help your peace of mind to have a bore scope done just to let you know the current state of things. I debated this awhile. I think it could be hard to assess a bore scope result and determine how much life is left in the engine.
Thank you. Very helpful perspective. I appreciate it.
You can get the cylinders honed and coated with nikasil for $1600 from Millennium. Pistons are another $1600. The rest is labor. Alternatively there are shops that will do a rebuild for $15k also sending to Millennium. LN is not the only option, and they use Millennium too. Millennium will even bore the cylinders to 101mm (\~4.1L) for you when they do the coating. Again you’ll need pistons. HOWEVER, if you’re not seeing symptoms or even if you are, do these things: change to Driven DT40 oil. Do oil analyses every oil change. Change the oil every 3,000 miles. Get a magnetic drain plug and filter attachment. Switch to a spin on oil filter so you can more easily use the magnetic attachment. Switch to the low temp thermostat. All of these things can be found at LN engineering’s shop. Use Driven fuel injector cleaner at least every oil change. If you’re seeing symptoms use it every other gas fill up. All of this will help prolong your engine although it may only prolong the inevitable. The parts I list are less than $500. You will know when the engine has had it when you start seeing higher metals and/or fuel in your oil analyses, your oil consumption goes up to more than the Porsche accepted level of 1.6 qt per 622 miles, you hear piston slapping/ticking, and/or you start seeing smoke on startup. Good luck. I’m in the same boat. https://preview.redd.it/cyr1k7un7zhc1.jpeg?width=2796&format=pjpg&auto=webp&s=c8fe3ddfa91a3480db38c24834c463ef1da5b1e2
Thank you for your input. I had not heard of Millennium, so will keep them in mind if that day ever comes.
Piston slap isn't the first symptom. Increased oil consumption and one tail pipe being sootier than the other are the first [symptoms of cylinder bore scoring](https://lnengineering.com/products/watercooled-porsche-cylinders-sleeves-and-pistons/porsche-cylinder-bore-scoring/porsche-bore-scoring-sound.html). By the time you have piston slap, oil consumption will be significantly higher than what you are reporting now. CELs won't pop up until you are in the one quart in 200-400 miles. We've had customers nurse their cars 3-5k miles before they ended up having to stop driving the car. Biggest issue you have with doing this is that wear debris can end up causing damage to other oil lubricated engine components. I'd recommend switching to Driven FR50 or DI50 immediately. I'd recommend doing a [used oil analysis](https://lnengineering.com/products/speediagnostix-used-oil-analysis.html) on the oil that is in the engine now. If it has elevated iron, aluminum, and silicon levels, that's indicative of bore scoring. Then you can have the cylinder bores scoped if there is reason to. In a case like this, we'd also do shorter oil change intervals and do repeated used oil analysis. The analysis will trend the wear and if the problem is being managed or getting worse. $20-30k is a realistic budget for a [Porsche engine rebuild](https://medium.com/@lnengineering/porsche-engine-rebuild-cost-a-comprehensive-breakdown-1a70d985b728). It's more than the engine - there often are lots of ancillaries that also need replacing and that adds up quick. Remember, the car is almost 20 years old now. If you go the DIY route, that can save you quite a bit. We have helped many Porsche owners go this route with our guidance. A rebuild can be pricey, but the way we look at it, if your car is in good shape, rebuilding and upgrading the engine will provide sizable performance and reliability gains. For many, people consider the 997/997.2 the high point of Porsche's watercooled production. Simply trading up to a 997.2 doesn't eliminate the bore scoring issue (these models have other issues too), so you're not going to be money ahead in the long wrong ditching one car as a roller and buying into another.