raidersfan

After reading the article in Panorama this month about Flat 6 and LN, with the statement that most of the engines they see feature bore scoring in #6 (instead of blown IMS bearing-related issues, most of which have resolved themselves by now), I began to wonder how many of the 997.1 engines actually have had bore score issues? 2-3% seems like an acceptable number, but as I see quite a few LN-rebuilt 997.1 models on the market, I wonder if the number isn't higher than that? 10%? 20%? If so, that is really unacceptable on a low-mileage car. I wouldn't consider bore scoring a typical age-related maintenance issue, unlike a fuel pump or clutch.

I am the Walrus

Perhaps owners will start scoping the cylinders as an added part of their oil change routine, from the bottom with the pan dropped, of course.
(maybe every 2nd or 3rd interval)
How much extra time and any extra supplies would that be?
Perhaps it’s not feasible..

TheBruce

I dont think 10-20% is even in the ballpark. That would be 10-20k 997.1s with rebuilt motors - a $400M rebuild business. To put it in perspective, I believe Flat6 does <40 rebuilds a year...including 986s, 996s, and 997s.

I think its probably closer to 1%. That could be higher (2-5%) for at-risk cars operating in cold climates.

JustinCase

This is an exceedingly hard question to answer. I doubt anyone knows with any degree of certainty. First, you are probably not just talking about 997.1s, you are also talking about 996s and all Boxsters and Caymans produced between 1996 and 2008 as all have essentially the same engine. I'm pretty sure LN Engineering could calculate a ratio (but not a percentage) of similarly failed engines at any point in time, but time keeps moving on. Same with Hartech in England. But they're not the only people remanufacturing failed engine blocks, just the best known. I doubt that they even know what their market share is.

Now to the article: (a) LN Engineering states that they were receiving an average of 3-5 engine cases a week in early 2018, and that (b) the number of failed engines had jumped up considerably since they saw their first scored bore engine in 2008. Since LN Engineering remanufactures all of Jake Raby's engines, it means that Jake is rebuilding no more than about 25% in North America and probably less, and that the other 75+% are rebuilt by other shops. Also, LN is not the only place that remanufactures engine cases since there are a steady stream of steel-relined cylinders turning up, and LN Engineering never has done that. Also, Porsche still sells that engine in replacement OEM short blocks, more-or-less in its original form, which are likely to fail eventually in the same manner as the originals.

An even harder nut to crack is that cars can be driven normally a long time after cylinder scoring has started to happen. I have personally been on more than one PCA event where I spotted 2-3 cars with blackened left tail pipes -- usually new owners who are not at all savvy and who obviously have not read the forums. Basically, they don't have a clue. One fellow even came up to me because I have a similar car and complained about the oil consumption and asked me about mine. Porsche really does not help things by formally publishing an oil consumption range that can "normally" be as low as 1 quart per 600 miles. My interpretation is that there are a lot of people who have eagerly bought up known defective cars sold to them by disreputable owners or dealerships who are unloading them as fast as they can when they find out. Since a fairly high percentage of Porsche owners don't drive their cars even 4,000 miles per year, it's going to be a few more years before they start having obvious problems and either rebuild, scrap, or sell their cars to other blissfully ignorant suckers. I'll take a WAG that more than half the cars with scoring are still out there, unrepaired. And more will be scoring into the future -- it's dynamic, which is why percentages are a wild goose chase.

In all likelihood, good, reliable numbers won't really be available until all M96/M97 engines have either worn out or been rebuilt.

Would I buy another used 997.1 C2S? Yes, I would provided no GT3s with Mezger engines were available or in my price range. But you better believe I would have an exhaustive PPI performed, with my offering price based on what is found. If it is a rebuilt Raby or other LN-remanufactured case with an IMS solution, updated LN chain tensioner and it passes PPI, then I would purchase it like any other car. If it is was completely OEM with no problems, I would expect a slightly discounted price, and I would start saving for an eventual engine rebuild at higher than the rate an aftermarket extended warranty cost (i.e., $1500 to $2000 per year, closer to $2000). If it had a scored engine, I would be looking at a price slightly below normal market rate minus my costs for rebuilding/replacing the engine.

I think over time, the market will separate into two classes: those cars which have been properly repaired and those that haven't. Original OEM market values will stay slightly or significantly depressed, but properly repaired cars will reflect a normal resale value as if these Porsche engines never had a problem. I also expect the delta between these two prices to increase over time as more people understand the difference. Currently, even Excellence magazine does not call out bore scoring as a known problem with their annual model-specific pricing and purchasing advice.

raidersfan

Well written and very informative! If LN/Raby is doing 200 or so engines a year; probably at least 2x that many are rebuilt using their parts by independent shops. I have a great shop nearby: I my first inclination would be to get it repaired locally. There are others using different parts, so perhaps another 200 or so? That is perhaps 800 engines a year, plus those that put in crate or used engines, which likely constitutes a significant percentage. I don't know how many were sold in the states: maybe 20,000 3.8L over those years? 5% a year have issues, with 3x that amount with scoring but not yet dealt with, in addition to rebuilt engines? We could be talking 25% or so.

bgoetz

I wonder how many get repaired because someone looks for and finds scoring vs how many legitimately needed repair. I also wonder how long the ones that were more proactively repaired might have lasted.

Take my car for example, it is currently getting a clutch IMS and part of the IMS certification is to check for scoring. Runs perfect, no oil consumption, no dark exhaust pipes, great UOA. If I find scoring the sump goes back on and I drive it till the IMS gets me or the scoring does. Save my $ in the mean time. Part of me would feel a bit foolish for even messing with it because knowing would undoubtedly put a dark cloud over the fun.

JustinCase

The cost to repair a scored engine is enough to pretty much give anyone pause, so I doubt that any normal person immediately or preemptively fixes it, especially since the decay can be quite gradual.

But when you are pumping oil through your exhaust system at a pretty good clip, you have to start worrying about what you are doing to your cats and anything else along the way. Contaminating and ruining them could add a lot to the cost of the repair. In my case, I drove mine with known scoring for 27,000 miles and did not get it rebuilt until I was adding 1 liter of oil per 500 miles. I suppose I might have been able to drive it a little longer for the price of more oil, but my used oil analysis was starting to pick up increasing fuel dilution in the oil and I did not want to damage anything else.

Note: I was still not getting the characteristic ticking noise, nor any CELs when I pulled the trigger. Maybe I could have made it another 10,000 miles or more, but knowing I would have to fix it anyway, why wait? As it was, 27,000 miles was sufficient to scare up the money to repair it. People who only drive 4,000 to 5,000 miles per year can probably go years before having to rebuild their engines.

996AE

991.1 are starting to show great reliability signs.

With exception of the TT and GT cars 997 may just start to loose over the top charm and high values.

NuttyProfessor

Great thread! I would love to know these numbers too. Jake Raby states that Bore Scoring is one of the oldest problems he's dealt with on the M96 and M97 motors. I'm also curious to see how this problem is going to affect 9A1 motors.

Well, cheers... heres looking forward to future bore scoring episodes on Raby's YouTube channel.

Charles Navarro

When we discuss scoring, it might be helpful to expand the discussion to Cayenne and Panamera models as well if we include the 9A1, as they all share similar hypereutectic cylinder technology, with the primary difference being silicon percentage and other added materials, like Alumina, which was used in the Lokasil I preforms, but Lokasil II does not have any alumina content.

Although there doesn't seem to be many engines that use the Lokasil process, Alusil is used by many European manufacturers:

https://en.wikipedia.org/wiki/Alusil

Functional differences between engines include cylinder orientation, rod stroke ratios, and other factors.

cannonball05

I think I read your situation in another thread but can't remember if you said you had the typical black drivers side tail pipe. Did you?

Balr14

That's rather disappointing. I was looking at a Panamera as a possible "family car", without the bore scoring worries.

JustinCase

Yes -- the main symptom that caused me to get my engine diagnosed.

bgoetz

Vincent713

All of the 997 I have been test driving has dark build up on both exhaust but they are dry. Is this normal or is it a potential failure?