EFFORTPOST 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.

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 cowtools, 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.

I wanted to change the injectors but the affordable OEM options were not available at that time.

Compression is good and less than 10% on all cylinders except for Cylinder 1, which suffers due to a leaky exhaust valve.

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.