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Why correct borescore?


8 Jun 2017
OK, let me preface this with 'my OPC say I don't have it', but here goes. This is a genuine question, not trying to upset anybody, not sitting one side of the fence or the other. Just genuinely curious about the subject that seems so important in these cars.

Is there something inherently risky in running a car that has bore scoring, or is it simply the cost of oil and a slight drop in power (I presume)? Apart from a puff of smoke, is the car at risk of imploding?

If there is no inherent risk to it, why does it need fixing? You can buy an awful lot of oil for £10k.

And a car with a rebuilt engine is not worth £10k more than the same car without. I grant you it is worth more, but not £10k more.

So why do people leap to an engine build the minute they see bore scoring?

I also accept we all like to tinker and make ourselves think the car goes faster after we have fixed the (fill in the blank) - mine is going much better since I changed the pollen filter, for instance.

(As an aside - changing the filter has actually taken away the whine from the fan (possibly less resistance?) so that's my fix this week.

Put the kettle on, enjoy...

I'd hazard a guess that leaving it would result in metal particles getting through the system and damaging various components. So while on the surface it would be okay initially it would eventually damage most components ie main bearings. And your car wouldn't be starting etc and would probably throw up error's.
You may say that the oil filter would catch it but if you're running a 2 year interval as specified by Porsche that is a long time.
seen a few people on here post they lived with it for a year or so until getting a rebuild.

For me Id likely get it done soonish (funds allowing) but couple it with a capacity increase (4.1 baby!!) so at least I felt I was getting something.
Bore score is essentially Grooves in the cylinder wall .. kinda like dragging you finger nails over a tub of butter .. the more you do it the deeper the grooves get .

The issue is oil gets into the combustion chamber ..

This will start as a bit more smoking than usual on startup from a single tailpipe and normally the left one .

You can indeed carry on using the car but as it gets progressively worse you will have more symptoms ..

Oil doesn't burn very well and so will leave deposits on the piston / valves but more importantly the spark plug ..

I don't really need to do a scope .. i just look at the spark plugs .. very easy to see an oil issue in a cylinder this way .

The problem is an oil fouled plug will start to cause misfires .. You could regularly change the plugs .. say every 6 months to start with .. down to every 3 months etc ..

The next issue is smoking .. i've seen excessive bore score on 3 cylinders .. you cant see the road behind you ... obviously that's not going to be legal .

When they get really bad you tend to get knocking noises .. piston slap .. the piston also wears due to this .

How long you can leave it .. i've seen a year on several cars and two years on a couple but never anything longer as logically one of the above will make it impossible to continue using the car .

On these cars we call it bore score but you get a similar issue to a much lesser degree on some Cayennes and Panameras ... oil fouled plugs is the first inclination of an issue here .

At the end of the day .. you are going to need liners and pistons on the affected cylinders so using it for longer is not really going to cause any further damage parts wise but thats IMHO .. and i'm not the expert when it comes to this .

Sooner or later though you will need an engine repair .
Many thanks folks.

I can't get to the link but the rest is useful info. As I said, I sign at the moment that it's heading my way (probably cursed myself now).

Thanks again

Copy and paste all of the above into a new browser. For some annoying reason I think the brackets are upsetting the forum coding.
OT but do the 06 engines have any better bore scoring protection than the earlier ones? Or was IMS the only real improvement? ta
On the contrary the most likely to score are the latest of the 996/7 (non GT3 or turbo) engines because they have bigger capacity, more forces pushing the pistons against the cylinder wall and a softer piston coating that cannot protect it as well.

Ironically the changes they made to make the cylinders stronger (to delay the ovality and cracking the earlier mainly 3.4 engines suffered) also made the pistons and bores more vulnerable to scoring so improved one issue and potentially made another worse. Meanwhile the piston coatings became softer (due to European Health and Safety legislation banning a process they were coated by) - so eventually the whole idea of Lokasil was abandoned.

Fortunately - although more expensive - the Nikasil plated alloy closed deck cylinders we use to replace the originals are extremely reliable.


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