It was 15 years ago but if you use Reid Vann just be very careful, I for sure caught them either being dishonest or incompetent (it wasn't entirely clear which but either way very bad) when working on one of my cars and that was the last time I ever went there again.

I was going to recommend calling Jon Rhodes at ET Tuning. He actually used to run Reid Vann back in the day like 20+ years ago when Reid was still more involved and it was known as a good shop. Jon knows Porsches and ET Tuning even has a dyno. I wouldn't have suggested to you to have a local shop like ET do the work but I would have told you Jon could drop the engine for you, crate it, and send it off for you until it came back at which time he could put it back in. Anyway, glad you're already at the back end of all this ordeal and can enjoy your car again.....better than it ever was.

 

Was shopping for my 7th 997 last year between June-August.
Found 2 local 997S cars both had around 75K miles. Both from Canada and for sale near Canadian border. Bore Scope Inspection showed terrible results with scoring on several cylinder walls.
Also both cars had heavy underside oxidation and rusted coil heat shields - The result of these cars being driven in winter on salted roads.
FF to September and found a 3rd car and what seemed to be a very nice cared for 997S with 68K miles in Portland. Had that car scoped and again poor results with scoring and one cylinder wall cracked.

Some photos from these 3 cars:



So I continued my search and in November last year found local Seattle 2006 997 C4 (3.6L) owned by Boeing Engineer. 106K miles and seemed well taken car of with service records and car was originally from Newport Beach California.
Had PPI/Bore Scope Inspection and was very pleased to see/hear the results were impressive. No scoring and my 40 year Porsche Specialist at Aker's Porsche said they were the cleanest 997 cylinders he's seen.
I use my 997 sparingly for date nights or short trips - I've only driven the car 1000 miles since purchase but just glad to know it has no scoring.
If these cars are cared for, at 120K-150K they look/feel drive close to new. Just like with the 3 996 C4S's I owned that had 115K-130K miles, they felt superb and tight.

Here are some photos of my 2006 C4 cylinders:






A valuable lesson is learned when shopping and Bore Scope Inspecting these cars. I recommend warm weather cars in CA/AZ/TX(no flood cars)/OR/WA.
If on east coast try finding cars in Carolina's/GA/VA. Careful of Florida cars that live on the coast - Seen some bad oxidation on those if not always garaged.
It is a must to have a thorough PPI and Bore Scope Inspection without fail.
Cars I have seen scoring have all been 3.8L "S" engines.

 

Not an expert but from the content I’ve read/watched about injectors suggests they can really be a contributor to the BS problem. The core issue doesn’t appear to be dirt/grime but rather mechanical wear over time that affects the ability of the injectors to properly atomize the fuel. Given how much is being done to the car, getting a new set of injectors seems like a reasonable step to take.

 

Per Jake Raby: I have over 300 sets of "real data" from injectors that were tested/ cleaned. Over and over again the cylinders that were scored had injectors that were leaking down, or had poor spray patterns, or both.

Charles - one year ago Jake told me that it appeared SUMEbore was even more impervious to bore scoring than Nikasil and said "my testing to see just how much fuel SUMEBore can retain ring seal with is happening very soon". Basically it seems like SUMEbore is going to completely eliminate this problem and be even better than Nikasil (performance-wise, not even considering that it is environmentally superior). As I understand it Jake no longer participates in RL discussions but will you guys be releasing more information on your SUMEbore research?

 

We're still evaluating the coatings and also looking as PTWA coatings to try them as well. Right now the suppliers of these coatings are not set up to support the aftermarket, so the cost to do these processes are prohibitive. We don't see it as an economically viable alternative for now and the work Jake and I are doing in partnership with Total Seal is solely for academic purposes at this time.

 

The Poll should have separate voting for 3.8L "S" engines in each category. I'd bet heavy very little scoring in the 3.6L engines compared to the 3.8L S engines.

 

Good Morning,

Just joined the list after poring over the last 500 or so posts on this thread! Such a fascinating crash course in an issue I didn't understand the full impact of until this weekend! It's also really cool to see pages and pages of active and supportive community conversation.

At any rate, what drove me down the rabbit hole was a 2008 997.1 with ~27k miles that appears to be in really great shape. I have it under contract and completed the PPI and Scoping (top down) from a reputable mechanic. Seemingly almost everything looks great (compression, deviation, all of the other cylinders), except for a "weird stripe" in cylinder 4. The mechanic is sure it isn't scoring, but also isn't sure what else it could be (hence the "weird".) His hypothesis given the horizontal line is that the piston sat in that position for a long time, and the thick vertical line that bisects it could be some kind of residue that developed there and was then rubbed against the wall when the engine was finally fired up. All of this is happening remotely as the car is many time-zones away from where I am. I wish I'd found you guys sooner, the images are from last week, and I've been dragging my feet with the dealer ever since trying to figure out what this is. I'm scheduled to give a final answer this afternoon, and the mechanic said it wouldn't dissuade him from moving forward as the other cylinders all look good, but I was hoping to put this to the hive mind for last minute a second opinion. Pics below!

Regards,
T

 

This is referred to as streaking and completely normal.
Your mechanic should know this.
Google search cylinder streaking or scoring vs streaking.
I think LN engineering had a white paper on this.

Harold

 

FYI- I had my cylinders done by Millennium Technologies, Plymouth,WI a couple of years ago and at this point everything is great! After research I discovered that the Nickel Silicon treatment is 10 time stronger then original cylinders. My car is a 05' 997.1 with 3.6 liter. Number 6 cylinder was horrible. I am sure as tech moves forward there will even more fantastic options! ...just my input to the conversation. Good day!

 

We use Millennium as well for our Nikasil plating however they hone our cylinders to our own specification.

Just to clarify, the plating is only applied on about .004"-.005" thick per side so it doesn't provide any structural enhancement, so you aren't addressing cracking or ovality issues unless you are using a process like our Nickies sleeves where the factory cast in liners are completely replaced. But yes, Nikasil is much more wear resistant than the factory uncoated hypereutectic cylinder bores and provides significant friction reduction and performance benefits over iron liners.

 

Wow that's fantastic news! Thanks for the quick reply, I'll definitely search out that paper also.

 

We commonly see this on stock engines. That "stripe" usually is where the gap lines up on the pinned second piston ring, but the fact that it is only on one cylinder and especially since it's on one of the bank 2 bores does make me question this.

The problem I see with these bore scope photos is that they are very poor quality and that they were taken from the spark plug end rather than from the bottom with the piston parked at TDC, so you're not getting a very good picture of what is going on (sorry for the pun).

Is the driver's side tail pipe sootier than the passenger side by chance? Any noises that might sound like a lifter tick once the engine is at full operating temperature like in the videos I posted on our website over the weekend:

https://lnengineering.com/products/w...ing-sound.html

 

Glad I could help!....

 

Thanks for replying. As best as I can tell, no sign of that clicking and no soot. But for the latter it could have been cleaned. If it wasn't the gap lining up, any other common offenders that could cause that kind of stripe? Would scoring below manifest with that kind of striping above?

Regards,
T

 

My car never had ticking noises or CELs, but I did have a sooty LH tailpipe which would show up after a tank or so of gas. The other symptom I had was a steady degradation of oil mileage, ultimately down to a liter of oil for less than 500 miles. Soot can be temporarily cleaned off, and I am not sure how one goes about getting oil mileage data.