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I would walk; no doubt. I counseled my friend during his recent 997.1 S rebuild, and it was painful, and he owned the car since nearly new. His had scoring slightly worse than what you are showing but some of the worst knocking I have ever heard.
I too am considering a 997, in particular a 997.2 S, and after my friends' experience and the number they built, walking is so easy to do until you find another one.
Don't fall in love with a car. While it may not be a 100% issue with a warranty, your future sales price and possible hassle with the warranty company may not be worth it. There are many 911s for sale, will be more with the nicer weather. Keep looking is my suggestion.
Here is a good photo from the LNEngineering website of what they considered typical cylinder scoring worthy of repair. It looks less scored than the photos you provided if I am seeing your photos correctly. Note that in this photo the cylinder has been sitting out exposed a bit so there is some weathering. A Google image search will find other similar examples.
I have to ask how many hear have seen a lot of borescope looks at cylinder bores before? Just curious what the percentage would be. We do pre purchase inspections of all types of cars so I am just wondering how many are commenting out of first hand experience.
I have to ask how many hear have seen a lot of borescope looks at cylinder bores before? Just curious what the percentage would be. We do pre purchase inspections of all types of cars so I am just wondering how many are commenting out of first hand experience.
And to the commenters here, when does bore scoring become a fatal flaw? Does it always end in relatively catastrophic engine failure?
Or, is the decline more subtle? Is it possible it's just increased oil consumption, smoky exhaust fumes, reduced engine power, etc. - things one can live with to avoid a $20 grand rebuild bill?
Last edited by jchapura; 02-01-2016 at 11:07 PM.
Reason: Re-jiggered a sentence.
Bore scoring is affecting many high performance and, generally, many modern engines. Theories are all over the place, but some common themes:
Once exotic-type performance required a caring owner, wise to the nuances of easing an exotic engine to life, ever concerned with a proper run up to temp, by driving smart, easing up the engine temp and living by the oil temp. The owner got in the car, started it, eased away and the car balked until all was right. You couldn't hammer on it; you wouldn't hammer on it. Not until all was right and warmed.
Today, exotic engines and engines with exotic levels of performance (over 100 HP per liter!!) are now daily drivers, which get remote started in sub-zero weather, idle for 15-20 mins, never warm up properly, then get hammered onto the freeway at 5000 RPM with oil not even above 100 degrees and metals not heat soaked. The excessive idling and extended rich, cold running wash away the oil, the lack of revs while it putters alone in the cold keep the oil from being splashed around well enough, etc.
On the 997, and the bank of cylinders with the scoring problem, the additional theory is that the coolant flow there is slightly less than optimal, due to hose length and some other very small variables I can't recall, but it can lead to a localized severe hot spot under just the right conditions.
Bore scoring as seen in those picturs is caused by two things. Lack of lubrication or contaminates in the oil or incoming air. Pretty simple really, it is not a mystery caused by some unknown cause. Well the could be on eother possibility and that would be contaminates during assembly. Keeping the oil changed and clean as well as the airfilter clean and air box sealed goes a long way to keeping things like this happening. Most scoring from normal use comes from initial fire up. If cars sit for prolonged periods it can be worse for sure than an engine that is ran normally and maintained
from my understanding, symptoms are all those things including a knocking noise... and when it gets really bad the cylinder will crack to the point of D-chunk failure.
happened to someone i know on these forums. based on his posts it destroyed him (financially).
to the OP i always tell people looking today that if i were in the market knowing what i know now id be looking for 997.2... not saying they are 100% problem free either but i think much more solid engine reliability wise.
Originally Posted by jchapura
And to the commenters here, when does bore scoring become a fatal flaw? Does it always end in relatively catastrophic engine failure?
Or, is the decline more subtle? Is it possible it's just increased oil consumption, smoky exhaust fumes, reduced engine power, etc. - things one can live with to avoid a $20 grand rebuild bill?
Bore scoring as seen in those picturs is caused by two things. Lack of lubrication or contaminates in the oil or incoming air. Pretty simple really, it is not a mystery caused by some unknown cause. Well the could be on eother possibility and that would be contaminates during assembly. Keeping the oil changed and clean as well as the airfilter clean and air box sealed goes a long way to keeping things like this happening. Most scoring from normal use comes from initial fire up. If cars sit for prolonged periods it can be worse for sure than an engine that is ran normally and maintained
Think you got it wrong that there are only 2 things leading to bore scoring and it is not all that simple but a matter of several things working together to create this. If there would be contamination either lubricating oil or air you would note that on both cylinder banks where most of the time (I still need to see the first case of bore scoring on bank 1 -driver side but maybe others have seen this) you see the bore scoring on bank 2
Example,
- inferior cooling water design. Thermostat on the wrong side and cooling water not coming to the area where it is needed to be. Bank 1 (driver side) do not suffer for the reason that the coolant enters on the bottom where the piston loads are at the highest at the bottom. Bank 2, piston loads are the highest at the top while the cooling water enters from the bottom. Local hotspot leading to very hot local temperatures which effects lubrication parameters.
- Internal cooling water bores weak design.
- Open deck design with cylinder walls way to thin.
997 is a good engine but due to the design has a few weaknesses which might result in bore scoring - or worse a catastrophic failure.
All described in various links.
I am not a Porsche engine rebuilder as I am professionally occupied with engines starting from 10 000 HP up to whatever- is- achievable. However I have rebuild a few 997 3.8 engines and believe there is a lot of controversy about 997 engines on the internet. Some engine re-builders, no names published, in my opinion are plain wrong in their approach (other than get lots of money of your pocket) as they try to fix the bore scoring where this is not the cause but the consequence of several things.
I don't make my money with fixing Porsche engines, pure long time hobby, nor I do run a rebuilding company.
I am with Rikky, as this topic has no doubt been beat to death here with regard to 997.1 engines. Walk from the car and avoid the headache of a rebuild.
I personally think, having been through a few rebuilds in earlier water cooled cars, that there might be a cavitation issue in some of the water jackets as Rikky suggests, but that is all conjecture.
What is not conjecture is if you see scoring like this in a 997.1 car, don't buy it.
02-01-2016, 08:49 PM
