69 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHIMSB failure vs Bore Scoring - and the winner is . . . .
Leading reported evidence
Replace engines
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
IMSB failure vs Bore Scoring - and the winner is . . . .
Frequently discussed work
Clean sump plate
No successful repair reported for this finding.
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Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion
Many would claim that you could keep a close eye of ferrous metals in the filter and sump, but what if the seller is changing the oil more regularly and cleaning the sump plate.
IMSB failure vs Bore Scoring - and the winner is . . . .
Read full discussion summary
Leading evidence: 'Replace engines' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Clean sump plate' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
IMSB failure vs Bore Scoring - and the winner is . . . .
Clean sump plate
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
Many would claim that you could keep a close eye of ferrous metals in the filter and sump, but what if the seller is changing the oil more regularly and cleaning the sump plate.
IMSB failure vs Bore Scoring - and the winner is . . . .
Replace bearing
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion · Original poster
At least if I was ultra paranoid I could buy my 996, flatbed it home and replace bearing with zero chance of a failure.
IMSB failure vs Bore Scoring - and the winner is . . . .
Replace dead battery
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
and 24% of owners are waiting for someone to help them open their frunk to replace a dead battery.
IMSB failure vs Bore Scoring - and the winner is . . . .
Frequently discussed actions (10)
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Clean sump plate
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
Many would claim that you could keep a close eye of ferrous metals in the filter and sump, but what if the seller is changing the oil more regularly and cleaning the sump plate.
IMSB failure vs Bore Scoring - and the winner is . . . .
Replace oil more regularly
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
Many would claim that you could keep a close eye of ferrous metals in the filter and sump, but what if the seller is changing the oil more regularly and cleaning the sump plate.
IMSB failure vs Bore Scoring - and the winner is . . . .
Coverage and how to read this overview
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
69 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 1 excluded by outcome qualification · 0 adjusted by outcome qualification.
2 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
I'm still not understanding where you came up with that number and how it applies to this thread.
. . . for killing the joy of finding and enjoying a 996 I say the winner is: Bore Scoring! At least with the IMSB you can be preemptive and take action at a reasonable cost but with BS there doesn't seem to be a definitive cause and there is no fix once you've got it.
Anyway, I'm here in San Diego and this is my first post. I'm looking for the nicest 996 6spd I can get for around $20k. Been reading a lot here and elsewhere and watching the excellent Flat Six series but I still can't get a handle on the volume it affects. I know my best bet is to go with low but consistent miles, known usage and service history and buying an example from a warm climate AND then get a PPI that includes scoping the cylinders and oil filter inspection. But still, what is the best guess as to how rampant this problem is? AND, is it really just inevitable with enough miles? When (or if) I get mine I will have the PPI focus on this problem since any external failures (water pump, AOS, even the transmission) post purchase will seem relatively minor.
From my readings, estimates that the single row IMS failure rate is 5-10%, double row is 1-2% but anyone have guesstimates on what percent of engines will get scored bores by a certain number of miles? Thanks much in advance.
200,000 miles is good before major engine work. Porsche knows percentage of 996 engines that reach 200k, major engine builders Jack Raby and Barry Hart can probably provide a good estimate. I'm not aware of anyone outside of Raby and Hart that have enough data points to make a reasonably accurate estimate.
Cylinders were a design flaw. Mk2 996s get bore scoring and Mk1s bore scoring and cylinder ovalization leading to cracking. Would be great if experts would provide estimate how many likely to make it to 200k.
Hint; when taking tech advice from forum, vet/research it's from respected/reputable members. Click on members screen name and scroll through their comments. Try brian996 for example.....
You again.
Where is there mention of 200,000 miles?
Exactly. Bore cracks left undetected lead to d-chunk. Put that ahead of IMSB. Maybe even ahead of bore scoring. YMMV.
Cylinder Bore Scoring vs. IMS Bearing Failure? The Battle for Ultimate Champion of the M96 Knockout, huh?
Is this like Rocky Marciano vs. Joe Lewis or Mike Tyson vs. Muhammed Ali?
My thoughts...
Both problems can eventually lead to catastrophic failure. Most owners of the 996 wouldn't dispute that claim. However, one is more predictable and easier to diagnose than the other. One is quicker to death and loves the element of surprise, the other is a slow choke hold that will eventually take out the engine as well. Therefore, both of these problems are not something to take lightly as potential owners of these cars. Most people with a simple bore scope and a pair of mechanic's ears can diagnose the health of the cylinder bores. Not the case with a failing IMS bearing.
But how would one truly know the health of a intermediate shaft bearing?
Many would claim that you could keep a close eye of ferrous metals in the filter and sump, but what if the seller is changing the oil more regularly and cleaning the sump plate. The tech pulls the filter during a PPI and boom, nothing in the filter media. Clean! But still, a sleeping giant is about to awaken. You jump on the forums and drink the kool aid that says, "These IMS bearings are unlikely to fail". This is kind of like when the doctor advises you about high blood pressure because it "runs in your family". You brush it off because, "My great grand daddy lived to be a 105!!!". The doctor insists you change your diet and begin regular exercise, but you ignore it and then one day while driving to work on a calm day... boom! Out of no where comes a heart attack!!! Dead!
Cylinder bore scoring on the other hand, is like having blood work done and CT scans and the doctors conclusively diagnosing the early onset of clogged valves on your heart. You're given a prognosis and a window of time for intervention. It's up to you to make the right choice. Jake Raby says this is a good failure to have, because if you catch it early enough, you can save the engine. Unlike IMS bearing failure, it's not as unpredictable. Most people will begin hearing a ticking sound and then with a simple bore scope evaluation, rule out all of other possibilities.
IMS failure is like surprise attack. Ambush if you will. Bore Scoring is like seeing the enemy far in the distance.
My vote is IMS failure being the worst.
If buyers knew percentage of 996s whose engines reach 200,000 miles before major work, they could estimate the chances at 133,000 miles they spending $11k-25k and lots of time working on that engine. After Nikasil cylinders installed in engines like yours it would also be good to know how many as % reach 200k.
I'd venture to say that an extremely small percentage of these engines reach 200,000 miles before major work is needed.
I'm still not understanding where you came up with that number and how it applies to this thread.
Should I preventively replace my soon to be scored bore or wait for failure?
I have replaced nearly everything that might fail accept this and I am losing sleep.
As for maintenance I change my oil monthly.
I was told that will lower my risk. It that true?
^^^ This seems to be a common occurrence with/in the "younger generation" - not necessarily today's "younger generation" but all "younger generations"... Intelligence or IQ is inherent - some are born with the ability to absorb and store huge amounts of raw data - this doesn't mean that they're able process it or make it useful. For this they need education/experience. Unfortunately, good education seems to be lacking in so much of today's society world-wide...
Wisdom
is gained from a combination intelligence, good education (this doesn't always mean "school" in the traditional sense either) and experience.
Yes, I agree that a "common sense" knowledge, as we like to say, goes a long way with solving rudimentary challenges that even a so perceived intelligent person may wrestle with. Do you think he washes his hands?
996 owner's dogma:
Our two weapons are fear and surprise...and ruthless efficiency.... Our *three* weapons are fear, and surprise, and ruthless efficiency...and an almost fanatical devotion to Porsche.... Our *four*...no... *Amongst* our weapons.... Amongst our weaponry...are such elements as fear, surprise....
Do you mean because they have the factory dual IMSB? For BS I haven't read anything about 99's being favored. They have the same cylinder material.
I'd have given d-chunk a distant 3rd for a street use 996, but maybe I need to read more?
I agree it's the worst if you do nothing about either. At least if I was ultra paranoid I could buy my 996, flatbed it home and replace bearing with zero chance of a failure. With BS all I can do is hope I don't get it.
I'd like to know this. I haven't seen any 996's advertised with over 200k miles. Maybe 150k tops. Ideal info would be something like: 2% at 50k miles, 10% at 100k miles, etc, but it sounds like comprehensive date is not available (it does seem like it might be 99% will have BS at 150k miles though).
Jay Leno likes to say Porsche drivers, unlike Ferrari, brag about their original engine/chassis having high miles, 2xx,xxx, 3xx,xxx but I guess that ends with the 996.
I had this annoying ticking sound coming from bank 2. Bought a pair of noise cancelling headphones....problem solved! In fact my 996 now is as quiet as a Tesla.
When did I stop thinking about women so much...when I got a Porsche, that's when! Now I think of the infinite modes of failure in that engine everyday. I look for tell-tale signs every waking moment: is that an oil drop? a tick? soot on the tail pipe? white or blue smoke... and it goes on
ad nauseam.
I barely remember what men and women are supposed to do when they get together; I'm thinking its talk about the health of my engine.
Forums can take you down a rabbit hole pretty quickly. You also have no idea the knowledge of the people actually posting. Go talk to a couple of independent shops in town and get their perspective. The two Indy's I've gone to and spoken with speak very highly of these cars, and in real life don't see many of these issues posted on the forums. A lot of high mile cars out there that have been driven and maintained. Reading these forums, you would think these were blowing up all over the place. Just be diligent in your search for the car that speaks to you, get a thorough PPI including scoping top and bottom. Maintain the car like Jake states and enjoy thousands of trouble free miles with a smile. You can't get a better sports car for the money IMHO.
I think Macster's Boxster has over 225k if I'm not mistaken.
Biggest concern I have now is that in the last couple of years I've really cut back on using the car because of my work situation (been out of town a lot). So if constant usage is a way to keep these problems from happening then I'm stacking the deck up against myself now.
I guess we'll see. I love the car but still on the fence as to whether I should spend the money to rebuild it or look for a newer 997 or 991 instead. Decisions decisions...
Porsche knows but won't release because would damage their reputation. Jake Raby or Barry Hart could give good estimates, but most forum regular posters want to be Thread Sheriffs, Troll Chasers, or talk about KY Jelly rather than ask them.
A few fun facts (then we can throw in conjecture):
Porsche imported about 51K 996s from 2000 - 2004 (sorry, not sure on 99s).
Of those, a full 72% are still registered for road use in the U.S. today.
That is an incredibly high number relative to most anything else sold.
Thus, do we really believe that both major problems are affecting the majority of the 37K+ 996s out there today? Just thinking about probabilities...
The statistics be damned. In the end, it comes down to one car....the one you want to buy. That car and its condition is all that matters.
Take a chance and buy one without a PPI or take a slightly lesser chance and buy one with a PPI. In either case, you are playing against the house.
Eventually, the engine will fail (as all engines do). Will the engine fail from one of the many documented failure modes or just the wear and tear of high miles? No one knows. You will only find out when you play the game.
So, place your bets and enjoy the ride. Hopefully, you will enjoy the game for a long time!
There are numerous databases that contain registration or vehicle in operation data...
The number above represents all 2000-2004 996s that are currently registered somewhere in the U.S.
That may be true, but that stat is most certainly not made up.
Now let�s guess what portion of the 37K+ remaining cars have...
-Replaced engines
-Rebuilt engines
-Replaced IMSBs
...or how many owners even know of these two issues.
In the corporate world, the left hand doesn't know what the right hand is doing. Ignorance is bliss.
Haven't seen much statistics come from Baz on the forums, but Jake Raby did say on his Bore Scoring series, that more than 80% of the cars that come to Flat 6 Innovations are being "reconstructed" due to cylinder bore scoring.
Would you care to share a link to just one of these databases?
And yes - even if true, it doesn't tell the whole story. As you mention above, how many are on their second (third) engine, etc? Having a high percentage still registered tells a lot about the desire to keep the car on the road. It doesn't say anything about how long the engine will last, how many miles are accumulated (max, min, avg, etc.), nor how many have been totaled and will never be used again.
I am going to say 95% of 1999 models are still on the road. I have it on good authority that that is the best year for the 996. There are plenty of databases to support this...
Just start replacing perfectly good parts and forget logic and reason
Sooner or later the 51 modes of failure will bite you (quoting an expert of course)
It is only a matter of when, not if
Here's a fun fact my rollers replacement motor has lived in three different rollers...An 05, an 01 and now my 02.
2 of the 3 are still on the road. What does that say?
Of the 72% (37k) still registered and on the road, 5% are for sale at any given time, 5% have dead batteries, 1% are waiting for FSI to rebuild, and .0027% i own, the extremely rare Arctic Silver Metallic c4s. I may let my registration lapse so i can market it as an even rarer, off the road, Porsche.
�I was told there�d be no math!�
The 05 had IMSB failure and was wrecked shortly after getting it's factory replacement. It then went to the 01(IMSB I think) but tuning was an issue so it was pulled and sold to me with 50Kish miles.
So...is there only one used M96 engine floating around Hawaii?
Reminds me of an old joke about breaking up with your significant other in a small town.
