Jdubsquared

JustinCase

We all die, sooner or later. So do the engines of our cars. Don't waste your life worrying too much about either. Too many other things to focus on. Take comfort in the knowledge that (a) seems like your car has been optimized to prevent scoring already and (b) even if it should score some day it will come on over time and not be catastrophic (like the IMS could have been). You can still drive it for quite a while, particularly since you are not putting that many miles on it a year. Keep being prudent, stop worrying, and enjoy.

TheBruce

JustinCase - glad all ended well. Sounds like you have a great build now that will last you a long, long time.

Interested to hear a) costs and b) your post mortem on the cause/effect and c) how your chain guides looked at 47k miles. I know this was an issue on the 996 but understand they improved the design on the 997.

JustinCase

Well . . . you know how it is when you are selecting alternatives and options "since we have the engine apart." Cylinder 6 was badly scored, none of the others were beyond a little wear on the piston skirts. It was a clear case of a scored cylinder, plus I know roughly when it started because I was logging oil consumption. It happened on my watch, but I had been doing everything right (easy driving under 4,000 RPM until oil reached 200F, oil changes every 4,000 to 5,000 miles, etc.). I did drive in some very cold weather for WA State (i.e., in the teens), but gee whiz! Original IMS and RMS were in great shape, but I opted for the IMS Solution so I don't have to think about it again. Chain guides were definitely worn, but not worn out. Replaced guides and tensioner (LN billet tensioner). Replaced AOS, clutch, ignition cable, water pump, and a myriad of other things "just because we are in there." Basic cost was about $18.5K, but the extras drove it up to a little over $22K. The hardest part was driving the company van for four months while simultaneously going through withdrawal. However, the extra time allowed me to save up for the final bill. Now that I am driving my 997 again, I don't really notice too much more power, but I can really feel some extra, lower RPM torque. My wife also says it is louder. No measureable oil consumption (!), but my gas mileage is down a little, possibly driven by a more erratic break-in driving style. I want to actually measure everything on a dyno for a BEFORE/AFTER comparison when I get a few thousand miles on it. From my perspective, the bore score deniers/trolls are whistling past the graveyard, especially if they drive an "S."

TheRealStig

Afternoon all, just got the diagnosis of bore score.
2007 C4S with 120,000kms on it. Irish car, so all elements of weather but rarely over 25 degrees C.
Over rev shows all good. I only own it since Oct of last year so I can't account for how it was used before I got it.
Symptoms were high oil usage (1.5l per 1000kms) and very sooty LHS pipes. No other signs.
Porsche dealer warranty so they're scheduling a rebuild.

onsickm

TheRealStig

120k kms & yup.

Climarepair.com

Porsche just raised the limits a year ago, now is up to 15 years or 200.000 kms (before it used to be 10 years / 150.000 kms). I guess same applies to the US market, translated to milles.

TheRealStig

Aaaand she's back.
Six weeks, new block & pistons, new clutch, replaced alternator cable & six new plugs.
Like a new car!
Rebuild at their cost, clutch, cable & plugs at my cost.

lou-in-nj

I bought my 2006 997.1 Carrera S with the 3.8 L engine with a thousand miles on a freshly rebuilt engine from EBS because of bore-scoring according to the previous owner. While I have not poured over the invoices from EBS, I suspect the replaced parts, piston and bore liners, were OEM. Since the car is not my daily driver, I've delayed putting in time to research what EBS actually did during the rebuild. However, in my experience, whenever there is bore scoring involved with any engine, my experience tells me it's either lack of lubrication, or bore / cylinder mismatch in expansion. I've monitored the lubrication aspect of the engine, and I find it difficult to believe that in a horizontal cylinder configuration, where oil level is easily monitored on the dashboard, that the scoring is due to lack of lubrication. I am more of the belief that it is a thermal expansion issue which is why I would advocate owners of these engines warm them up very carefully before they put a substantial load on them. I find my oil temperature takes about 10 minutes to get to normal operating temperature, but at that, I still limit the load for another 5 or so minutes to ensure all the internal parts have acquired the heat necessary to get to their normal operating clearances.

//steve\\

I think letting the engine get to proper operating temp is likely a lot of it. You see wild ends of the spectrum with the E90/92 rod bearing issue and I think it's the same reason. Tons of non car guys that own them that will start the car cold and peel off as soon as they leave the neighborhood. Both are more expensive status symbol sports cars so there will be a huge population of people with them that just don't treat it like their baby.

You'll find instances of both cars where people have had the issue at 20k miles and others well over 100k with not a single problem.

Fahrer

I agree with this 100%. My owner's manual for my 2008C2S indicated that the break-in period was 2500 miles. I am sure many people do not wait that long to break-in their cars. Leased cars? .... it's not their problem. It will be someone else's problem. Both my 2016 Audi A6 and 2016 VW Golf owner's manuals say how you break-in your engine and how you drive it when it is cold after startup will have a significant impact on what condition it will be in as it ages. And, still, I read nonsense that one should "drive it like you stole it" to break it in. The manual for my 911 stated that one should drive at steady, constant speeds, light throttle and maximum revs at 3-4 K for the break-in period. I followed that and my car uses very little oil. I also use light throttle and keep the revs bellow 3K until the oil reaches 200F.

lou-in-nj

@JustinCase
What do hou attribute the scoring to? What were your cold start/driving habits?

JustinCase

It's not clear. I purchased the car with 10,000 miles on it. Symptoms did not turn up for another 10,000 to 15,000 miles, so I believe the problem developed on my watch even though it had been at a dealer for a while and I'm pretty sure there was some hooning going on with it. Since I have had the car, I always drive it out of the enclosed garage right after starting but keep it under 4,000 rpm until it reaches 200 degrees F, and I have a long-time habit of rev-matching the shifts. While it is my DD, it rarely gets even cold enough in the Seattle area to switch out my summer tires. Winter is 25-30 degrees at night and 45 degrees in the daytime. There was one incident early on where I drove it to work when it was 19 degrees F I thought might have been the problem, except when I matched that date to my oil consumption and symptom chart, is was many, many miles and months earlier, so it's hard to believe it was the precipitating incident. I am struck by a statement Charles Navarro of LN Engineering made that *all* the 3.8s he gets in are scored, but I also know he only sees engines with problems, not engines *without* problems. Incidentally, once symptoms showed up around 25,000 miles, they progressed fairly rapidly until I had to do something by 45,000 miles. Oil consumption was dropping like a stone, and I was at 500 miles per liter when I had the engine rebuilt. I apologize for not providing a crystal clear answer. By the way, running a DME when the engine was rebuilt showed only a few overrevs in Zone 2, and only one in Zones 3,4, and 5 -- but based on the hours, that happened many, many moons ago, and before I purchased the car.

808Bill

Dealers are famous for starting a hipo car and revving it to show off...