Percentage of M9X engines with borescoring?
06-05-2023, 07:07 PM
#16
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I took apart a 3.6 with 102K miles. Not much scoring, so I dunked the whole case in PurplePower to give me a reason why I was in there in the first place. 🤣 Now I have a 4.0 with Nickies.
06-05-2023, 07:47 PM
#17
It's nowhere near as bad as some particular people claim. I've read 8% but the excerpt below claims around 5%.
Porsche GB advise that it sold 9,710 996s and 997s in the model years 2004-2006. Some very wet-finger-in-*the-air guesswork suggests independent specialist rebuilds and OPC warranty replacements combined may have reached 500 engines from that period, which indicates an overall percentage of around five per cent.excerpt: GT Porsche Magazine
M96_M97_GTPorsche-Cylinder-Bore-Scoring.pdf (rpmspecialistcars.co.uk)
.
Porsche GB advise that it sold 9,710 996s and 997s in the model years 2004-2006. Some very wet-finger-in-*the-air guesswork suggests independent specialist rebuilds and OPC warranty replacements combined may have reached 500 engines from that period, which indicates an overall percentage of around five per cent.excerpt: GT Porsche Magazine
M96_M97_GTPorsche-Cylinder-Bore-Scoring.pdf (rpmspecialistcars.co.uk)
.
There are a number of cars that are running around with bore-scores that have not yet been detected, reported, rebuilt, or owners don't want to know. Let's say another 5%.
That means 10% of 997 2004-2006 models have a single mode of failure of borescoring.
I don't know about you, but any design that has 10% failure due to a single failure mode is actually pretty bad. Certainly not five 9's reliability.
Don't be scared, but do be well informed.
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Yogibara (06-15-2023)
06-05-2023, 11:28 PM
#18
Rennlist Member
I would go as far as to say that their are a bunch of cars tooling around with not only bore scoring, but also an imsb in the process of failing as well as their aos and water pumps failing. Let hope these guys get their cars serviced soon.
06-06-2023, 07:35 AM
#20
Rennlist Member
06-06-2023, 10:52 AM
#21
Rennlist Member
I love the turbo but it has the same issue as the M96 powered 996. The issue is the previous owners and if they properly serviced the car or not. Buyer beware on any 20+ year old car. This us why you need to buy one with a service history to see what has been done and when, as well as perform an invasive PPI to prove its in great shape.
Last edited by GC996; 06-06-2023 at 10:53 AM.
06-06-2023, 11:02 AM
#22
Race Car
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diddy2003 (06-16-2023)
06-06-2023, 11:05 AM
#23
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wildbilly32 (06-06-2023)
06-06-2023, 11:10 AM
#24
Race Car
Good one Gary 👍
06-06-2023, 11:37 AM
#25
Rennlist Member
Originally Posted by zbomb;[url=tel:18842392
18842392[/url]]An instant classic. 69% dumber than anything else I’ve read today.
I think zbomb has been huffing too much gold paint again. I’ll have to translate for him. The same issue the 996 turbo and non turbo engines have is that the previous owners have either properly maintained the car or not properly maintained the car. Not the same mechanical issues.
poorly maintained turbo 996 can be just as disastrous for an unsuspecting new owner. The prices some of these turbos are demanding out there are very short sighted. They have folks believing the meztger engines are bullet proof despite years of abuse and neglect. Just not true. I wouldn’t want one without records, and pinned coolant lines.
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06-06-2023, 02:09 PM
#26
Racer
My 2cents....
bore score is the final symptom of failing loco-sil cylinders, don't have to wait for bore score to get excess blowby, piston slap, and oil consumption and loss of hp. Taper/out of round, most of the time is a precursor of bore score in m96 engines.
Out of round/taper is the real problem. that starts the cylinder down the bore score road.
I Bore gauged a very clean 2002 996.2 3.6 at 60,000miles, just a little while ago, with the owner, an active forum member here. He is a meticulous guy that maintains his car better than good. He uses DT40.
My take away from this bore gauge check,,,, cyls can look perfect with no score what so ever. Not even the smallest sign of wear. But measured at .0025"+ taper average on most cyl. Maybe 1 cyl went up to .0027". Been said on our forum in the past, .003 is max out of round/taper limit. In many other engines, .002" is max taper/out of round. So at 60,000 miles on a meticulously maintained engine, the block is almost out of spec. Probably the remaining piston coating would be gone by 80,000 resulting in heavy bore score from the taper/out of round.
So, IMO, what experts have explained in detail, the cyl structure is faulty. Correct me if I'm wrong, but what I've gathered here from the engine experts, the defective loco-sil materiel that is 1/4" thick lining the cyls collapses/changes internally(?) or on a molecular level, more or less causing out of round/taper. Now maybe poor maintenance will speed things up, but doesn't seem to matter what you do, by 80-100,000 miles block is probably shot and maybe been that way for half its life...
One of the largest expert Porsche engine builders have told us in the forum that by 100,000 miles most all 996 cyls will be over max out of round, and some by a huge amount.
Whats much more important in my opinion than " % of engines with bore scoring" is the 100% of engines that have/will have out of round/taper thats the cause/harbinger of dreaded bore score... Yup, once that piston starts slapping around in its out of round cyl, not long before all the ferrous piston coating wears off and aluminum on loco-sil starts to score the crap out of the cyl walls...
Some say bore score is not that critical, depending on its severity... Suppose thats up to the individual owner to decide. Both my 996 have around 35,000 miles and burn no oil between changes.
No piston slap noise, no smoke belching out of my exhaust, no constantly making sure oil level isn't critically low, no loss in compression/power. I know once the miles double, out of round will probably be there at max limit. Maybe not enough to cause any problems yet but it won't be long. Not sure if I could enjoy a high end sports car that does/has all of the above. Eventually all the grit/debris/piston slap from bore score will cause engine failure...
So to all of us 996 owners, just know this and plan accordingly....
jmho
bore score is the final symptom of failing loco-sil cylinders, don't have to wait for bore score to get excess blowby, piston slap, and oil consumption and loss of hp. Taper/out of round, most of the time is a precursor of bore score in m96 engines.
Out of round/taper is the real problem. that starts the cylinder down the bore score road.
I Bore gauged a very clean 2002 996.2 3.6 at 60,000miles, just a little while ago, with the owner, an active forum member here. He is a meticulous guy that maintains his car better than good. He uses DT40.
My take away from this bore gauge check,,,, cyls can look perfect with no score what so ever. Not even the smallest sign of wear. But measured at .0025"+ taper average on most cyl. Maybe 1 cyl went up to .0027". Been said on our forum in the past, .003 is max out of round/taper limit. In many other engines, .002" is max taper/out of round. So at 60,000 miles on a meticulously maintained engine, the block is almost out of spec. Probably the remaining piston coating would be gone by 80,000 resulting in heavy bore score from the taper/out of round.
So, IMO, what experts have explained in detail, the cyl structure is faulty. Correct me if I'm wrong, but what I've gathered here from the engine experts, the defective loco-sil materiel that is 1/4" thick lining the cyls collapses/changes internally(?) or on a molecular level, more or less causing out of round/taper. Now maybe poor maintenance will speed things up, but doesn't seem to matter what you do, by 80-100,000 miles block is probably shot and maybe been that way for half its life...
One of the largest expert Porsche engine builders have told us in the forum that by 100,000 miles most all 996 cyls will be over max out of round, and some by a huge amount.
Whats much more important in my opinion than " % of engines with bore scoring" is the 100% of engines that have/will have out of round/taper thats the cause/harbinger of dreaded bore score... Yup, once that piston starts slapping around in its out of round cyl, not long before all the ferrous piston coating wears off and aluminum on loco-sil starts to score the crap out of the cyl walls...
Some say bore score is not that critical, depending on its severity... Suppose thats up to the individual owner to decide. Both my 996 have around 35,000 miles and burn no oil between changes.
No piston slap noise, no smoke belching out of my exhaust, no constantly making sure oil level isn't critically low, no loss in compression/power. I know once the miles double, out of round will probably be there at max limit. Maybe not enough to cause any problems yet but it won't be long. Not sure if I could enjoy a high end sports car that does/has all of the above. Eventually all the grit/debris/piston slap from bore score will cause engine failure...
So to all of us 996 owners, just know this and plan accordingly....
jmho
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jandackson (06-06-2023)
06-06-2023, 02:38 PM
#27
Rennlist Member
The quote says 5% being replaced and/or warranteed.
There are a number of cars that are running around with bore-scores that have not yet been detected, reported, rebuilt, or owners don't want to know. Let's say another 5%.
That means 10% of 997 2004-2006 models have a single mode of failure of borescoring.
I don't know about you, but any design that has 10% failure due to a single failure mode is actually pretty bad. Certainly not five 9's reliability.
Don't be scared, but do be well informed.
There are a number of cars that are running around with bore-scores that have not yet been detected, reported, rebuilt, or owners don't want to know. Let's say another 5%.
That means 10% of 997 2004-2006 models have a single mode of failure of borescoring.
I don't know about you, but any design that has 10% failure due to a single failure mode is actually pretty bad. Certainly not five 9's reliability.
Don't be scared, but do be well informed.
At least it's pretty easy to scope the cylinders and take action to mitigate this issue.
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e30rapidic (06-06-2023),
GC996 (06-06-2023)
06-06-2023, 02:45 PM
#28
Rennlist Member
Yep, and pretty easy to test the oil as well. Not to mention mitigate IMSB, AOS and water pump failure.
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Charles Navarro (06-06-2023)
Just compare the maintenance life of a 996 to a Apprillia race bike.. Then it kinda makes sense..
06-06-2023, 07:29 PM
#30
Racer
Better than a 9A1
The beauty of the M9X is that is benefits from 20+ years of failure analysis and private sector solutions. We have choices on which “correction” we want to use in many cases. In my eyes, this alone makes the platform the least risky to own.
I see videos of the latest and greatest engines from Porsche and shudder to think of owning one of those. They have a lot more parts, are more expensive and have less development. AND they fail for many of the same reasons as the M9X along with their own special failures. As an enthusiast, that does not interest me.
I see videos of the latest and greatest engines from Porsche and shudder to think of owning one of those. They have a lot more parts, are more expensive and have less development. AND they fail for many of the same reasons as the M9X along with their own special failures. As an enthusiast, that does not interest me.