From the U.S.: 996.2 Carrera 4S Bore Scoring Inspection Images and Report

Car Info and Introduction: Year: 2004 Model: Carrera 4S Milage: 62,000 Miles Miles Since Last Oil Change: 4000mi Oil: Motul 8100 X-Cess Gen 2 5w40 Additives: 2 Bottles LubroMoly Ceratec Modifications: Low-Temp Thermostat, Magnetic Drain Plug, Rennline Tunable Semi-Solid Engine Mounts, LN Spin-On Oil Filter Adapter with NAPA Gold filter, No cats (stolen), LN Single-Row Ceramic IMS Bearing installed at 16,000mi. I thought I would write up some info on my car and its cylinder heath in order to track bore scoring progression, symptoms, and what I’m doing to slow its decline. While I am located in the US, I've found that the UK boards have their own experiences and opinions on bore scoring and would like to add my experience and receive more input. In my experience the more data and transparency, the better. 2004 Carrera 4S - Technically fourth owner. Was owned by two individuals before being purchased by my father in 2013 at 16,000 miles. Summer driven only except for a few regretful startups and idling in the winter. Maintained first at dealer, then independent specialist, then me once I started to become proficient. I was given the car by my father at 40,000 miles, although only transferred it into my name upon his passing. Previous Service: 4,000mi ago, in 2023 I experienced constant misfires in all cylinders on Bank 2 (4, 5, and 6). I diagnosed this as a bad Variocam solenoid. At the time I had some extra cash from some art sales, a lot of free time, and decided to do a minor overhaul/refresh of the engine. As part of the process I scoped the cylinders, both through the sump and spark plug holes and discovered very light scoring/scratching in some of the cylinders. Unfortunately I did not mark which image went to which cylinder, but an example of the worst of it can be seen below: Because of the minor severity of it, and the fact I’d just spent my $6k budget on parts and tools, I decided to go forward with the minor refresh and check back on the scoring during the next oil change. I pulled the engine and transmission and replaced the following (from memory, will add additional items if I recall later): spark plugs, coils, Variocam solenoids and actuators, AOS and all associated plumbing, power steering upper and lower reservoir and o-rings, oil cooler o-rings, cam position sensors, crank position sensor, coolant hoses, low-temp thermostat, coolant, water pump, magnetic drain plug, LN spin-on oil filter adapter, belt tensioner and pulleys, clutch, clutch slave cylinder (blew old one out upon reinstallation), MAF, vacuum hoses (replaced with silicone, intake gaskets and o-rings, checked oil pickup tubes for debris and smoke tested the engine. I also tossed on a fresh set of rear tires and welded the loose baffles in the factory Sport Exhaust. Compression is good and less than 10% on all cylinders except for Cylinder 1, which suffers due to a leaky exhaust valve. I wanted to change the injectors but the affordable OEM options were not available at that time. I chose to refill it with Motul X-Cess Gen2 5w40. Previously it has used LubroMoly 5w40. I added two bottles of LubroMoly Ceratec. The Past 4000mi: Further precautions included not letting it idle upon startup, driving only in moderate weather, and not revving above 3500rpm for the first five to ten miles. I am also careful not to lug the engine and drive taking advantage of the car’s momentum. So far the car has not exhibited any other symptoms of bore scoring. Plugs are not fouled, no ticking or slapping noises, and both exhaust pipes are clean as a whistle. Inspection Results: Drain Plug: One small shard of ferrous metal on plug, small amount of ferrous powder. Oil Filter: One spec of green Variocam seal, or or two brown flakes from timing chain guides. Spark Plugs: All spark plugs show even burn with no fouling or dampness. Cylinder 1: Cylinder 1 pics are from the top (plug side) only. Cylinder 2: Cylinder 3: Cylinder 4: Cylinder 4 shows the worst scoring. Cylinder 5: Cylinder 6: Cylinder 6 shows some discoloration/wear(?) at the bottom of the cylinder. I also am sending my used oil out for analysis and will add the results when they are delivered. Conclusion and Plan Moving Forward: I will be replacing the semi-solid engine mounts with factory mounts due to the data I've read on Rennlist regarding solid mounts. I wonder if my bad exhaust valve could be contributed to this. As the car is asymptomatic and scoring is still relatively minor, I plan on continuing to drive it while saving for a DIY rebuild. I put around 5k miles on the car per year, and feel I can get at least another 6k out of it before tearing it apart. If no external symptoms prompt me next year, in the fall I will scope the engine again to check progression. When the time comes I will send the block to LN for nickies and order the Jake Raby book and video series, while doing the labor myself. I’ve never rebuilt an engine before, but there’s a first time for everything and I can’t imagine my financial situation improving to the point where I could afford an FSI rebuild. I also don't want to spend $30k on a car that's only worth $35-45k. I do, however, plan on keeping the car for as long as possible. Over the winter my goal is to purchase and install a third radiator kit and install the LN Single Row Pro bearing, as the current ceramic bearing is past it’s lifespan and very close to the maximum miles recommended. Thoughts, analysis, opinions, and questions are all welcome.

Nice post! Personally I’d be driving it until you start to develop symptoms - you might find you’ve got a lot more than 6k miles in it before they develop! One question - is the car a manual or tip?

Blimey that's a very thorough diagnosis and future plan for the engine. Well done for doing that. It sounds like you want to keep the car for ever if possible and I don't blame you , there's obviously some emotional attachment with it being your late fathers but it's also a lovely looking car and the family has owned it for a good long while and most of it's mileage. I can't comment on the bore scoring in the very high quality photos you've posted but they don't look too bad at all to me, but I'm sure LN or Hartech could give you a much better appraisal if you haven't already done that. I would just keep doing what you're doing , monitoring it and enjoying the car and read up , watch as many Youtube vids as you can on rebuilding these engines so when you start you know exactly what to do and there's no part of the procedure you're unsure of. As far as I can see (after doing just that for a few years) the engines are very unusual in their design and layout but nothing too difficult to put me off doing it , the only tricky bit is those circlips for the gudgeon/wrist pins that you have to do with a long bar and then send the camera down there to check it's gone in properly. Good luck whatever you chose to do and let us know what happens.

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Pretty sure that's a manual in the photo

Great write up. As above I feel you would likely get a lot more mileage before it actually needs a rebuild but from it's history with you the car is obviously more than the sum of its parts to you and it's value to you is more than just driving it. Whilst the issue diminishes the ownership experience for a lot of people I applaud your attitude in making it part of the experience, good luck and I look forward to future updates.

Nice to see such detail - great job. My inspection revealed a very similar level of wear as yours and I have 100K miles on the clock. I doubt yours will need anything for a good while yet. Keep up the periodic inspections and enjoy the car!

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I'd definitely be happy to get a few more years out of it before a rebuild. US rebuild prices are nowhere near as budget friendly as the options you have in the U.K. - if you can even get a slot with FSI I hear you're looking at spending $35k. Hopefully the parts prices stay stable enough that it's still $10-15k to DIY when the time comes. I figure if I can set aside $5k for three years I'll be in good shape. It's a manual. I think one of the things this has done for me is forced me to stop viewing the car as an asset. In the US, manual Carrera 4Ses go for around $30-45k depending on spec and mileage, and while it's a convertible, I feel it's go the right options, colors, and conditions to get top dollar. I have no business in my life to be holding onto a $35-$45k car and there are a lot of better things I could be doing with the money. Now that I'm aware of the scoring, no matter how minor, and being an honest person who'd be compelled to disclose that to any potential buyer, the car is worth a lot less money. It wouldn't be possible to get a reasonable amount out of it by selling it. That said, I always have the option of investing $10-15k along with some labor and turn it into a $35-45k car again. Does that make sense?

Certainly does make sense if you're properly attached to the car. If you remove the engine and do the strip down/rebuild yourself I think you'll find $10k will be the max you need to spend , possibly a good bit less. Being handy with cars saves you so much money with labour rates being the biggest part of most jobs.

One thing to consider is shipping the engine to Hartech here in the UK, if it makes economic sense. They receive engines from all over the globe currently, so don't discount that as a possibility

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Hartech is definitely on my list of options to explore. That said I’m actually looking forward to learning how to do the rebuild myself - I’m sure that I’ll regret that if I mess it up, but I just can’t pass up the opportunity to dig into a project like that.

Very impressive analysis and diagnosis, please keep the thread updated. Not sure if it makes financial sense but maybe you could send just the blocks to Hartech and get the "nickies" by them. Good luck.

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LN Engineering here in the US will do nickies for $4600, and they’re just a few hours away, so it makes sense to have it done here. Pistons are another $1100, gaskets are $1000. Which isn’t bad, but all of the “while you’re in there” things tend to add up and I also need a valve job.

Congrats on starting your new Engine R&D company. What a fantastic project to claim the tax back on as your cab first the rank.

Hi I'm sure you know this, but as Jake Raby says, do not let the engine sit and idle from cold, and never let it labour by pulling away in a high gear (Tiptronic owners knock it down to 1st). My brother and I did a home full rebuild of a 996.2 3.6 Tip engine from bare case halves (machined from Hartech), so its certainly a DIY possible. We bought the Jake Raby videos and followed them. Over a year after the rebuild the engine still runs perfectly. IMS wise we got a larger late 997 bearing pressed on to an early shaft from Hartech. All the best Berni