Scored bores are scaring me off
 

Hey folks, I won't make another "I'm thinking of buying a 996" thread like so many.

But I am, however I'm not put off by IMS/RMS issues, I planned on dropping the tranny and doing IMS/RMS and clutch kit after buying a car. No big deal.

What I'm more concerned about is the scored bore problem, I know once it gets further along it creates noise, esp during a cold start, blue smoke at start up, usually on one exhaust pipe (with the bad cylinder).

I also know it can happen due to oil starvation on high cornering speeds, and very cold starts when the cylinder and piston expand at different rates.

Should I be worried or is it rare in warm climate cars? It doesn't seem that even PPI always catches the early signs of a scored bore.

I've been looking at cars with higher miles (100k+) and I've already seen a few, I'm assuming that if the motor was going to score its bore or blow a D-chunk it would have done it already.

Incidentally I'm experienced with cars and have a very good ear for odd engine sounds, I have a good track record with knowing something sounds off.

Thanks!

Your 996 is a 1000 times more likely to experience a mechanical failure due to mice...

Keep traps in your garage and never, ever, keep your garbage in there, no matter what time of year.

The bore scoring noise confuses me. There is a video from Flat 6 (Jud Fink) giving an example. What I don't understand is how does a scored bore make a sound like worn lifters ? I can't understand visually what makes the clatter.
There are lots more if you google "Bore scoring Youtube"
The one cause of bore scoring that gets more attention is starting the engine in extreme cold.Problem is said to be one of insufficient cold temperature clearances.
Just buy your 996 from a warm climate?

I think mice have taken up residence in Gonzo's head.

Having recently pirchased my first 996, I also was concerned about bore scoring. From my research indicates blue smoke on start up, increase in oil consumption and maaaaybe some noise are early symptoms. You can bore scope the cylinders through the spark plug hole and/or the bottom end of the engine to look for damage. Dropping the pan and pulling the oil filter to inspect for debris can also lend clues. This all can be part of a PPI on a car you are serious about.

That said, I did none of that and bought a car with a pretty clear past (service records, two owners and 55k miles) and my gut. I trusted the seller and my ear. No weird noises, no signs of oil consumption etc. car ran great. Three months later and 6k miles and still runs great. I changed the oil, dropped the pan and tore open the filter. All were clean to my great joy.

Do do your due diligence. Seems like you have been around enough to determine what that is. Then drop the hammer and never look back.

The piston motion will either rock axially about the wrist pin axis where the skirt strikes the cyl, or the piston will slap radially about the big-end axis where the piston skirt strikes the cyl wall.

Don't forget the cyl is a nice echo chamber, or audible reflector.

Yes, move to the warm climate and own a 996.

If you can live with the worst case scenario (however much it might suck) then quit worrying and go for it. Do your due diligence and just accept there's a chance things can go wrong. I'd equate your current logic to not wanting to buy a nice car because someone might pull out in front of you and wreck it. Yeah, it can happen, it does happen - but you're missing out on the joys of ownership. What's the old adage? Better to love and have lost than to never have loved at all?

Word around the block is that a good rodent prevention system (RPS) is the forgotten acronym that actually cures bank 2 issues.

That is Jake talking not Jud.

You have described Piston Slap. Bore scoring is a different noise ? If the scoring is so bad it has ovalised the bore ,then yes, that will sound just like Piston Slap.
Or the score marks are so deep you loose the oil film.
IT seems more likely on Bank 2 because the wrist pins are not offset.

I was crediting the listed Poster of the video to help people locate it

Ok. I listened to it twice, although my laptop speakers aren't great, that sounds like a piston moving in the bore. In an air-cooled engine the sound is more of a ringing noise. I can only surmise that the water jacket provides a bit of damping effect, but it sounds like piston striking the cyl wall to me. Meh - I could be wrong. ;)

This thread is a perfect example of what causes a "Rennlist" complex. If you read these boards consistently, you will convince yourself that your car is seconds away from a nuclear meltdown at all times. Like the block is made of paper mache and the pistons from gummy bears.

The reality is that Porsche has been at this a while and sold a ton of 996s through the years. Are there known issues? Yes - but owners have found ways to deal with them.

Do all bores have scores in them? Yes. Do some score worse than others? Yes. Just watch the oil consumption, which will not be 0.

Pick and good one and maintain it. These are tough little cars! Don't be afraid either.

Bore scoring is easy enough to check for in a good Indy shop , it will add a little extra to the cost of a ppi but worth it . They just have to pull the spark plugs and scope the bores

He is smart ! Since we have embarrassed ourselves with inability to distinguish between the noises - just borescope with the piston at BDC

Thanks everyone, seems if I make sure I get a west coast car which hasn't been used in very cold weather, the car hasn't been tracked etc then should be good.

I've had a 3.2 carrera and boxster before so I know these engines do use some oil.

As an extra check if/when I buy a car, when I'm doing the IMS/clutch I will pull off the oil plate from the engine and scope the bores from there, I have a camera myself so it won't take me long to check.