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YOUR RESEARCHNew member just bought this
Reported or suspected cause
have a clean bill of health
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
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Discussions that report identifying a cause
1
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Reported cause
Fortunately it turned out to have a clean bill of health with regard to bore scoring.
Leading evidence: 'have a clean bill of health' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'have a clean bill of health' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Clean bill of health' (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.
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Discussions that report identifying a cause
1
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Reported cause
So it was the high mileage that brought the price down, not any sort of neglect or needing major mechanical repair.
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.
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Reported cause
I have diagnosed a fixed ( on the internet and in person) several of these with "tapping noises" that everyone suspected was something sinister like Bore-Scoring....when they turned out to be a loose Cat or Carbon Build-up on the Piston Top and a can of CRC Carbon Remover cured the Tapping noise, or just replacing the Loose Cat..
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 report identifying a cause
1
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0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
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
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Performed · outcome unconfirmed
They also pointed out than it has an IMS Solution installed too.
Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
It was acquired by the seller last month and the first thing he did was to try and get it to stop burning oil so he replaced the AOS, spark plugs and O2 sensors.
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Suggestion
All you gotta do is replace the factory AOS with the UAOS w/ Track Drain and you can not only run full oil (8.5 qts), but you can actually overfill it with up to 2 quarts over full (10.5 qts) using the UAOS Track.
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
I have diagnosed a fixed ( on the internet and in person) several of these with "tapping noises" that everyone suspected was something sinister like Bore-Scoring....when they turned out to be a loose Cat or Carbon Build-up on the Piston Top and a can of CRC Carbon Remover cured the Tapping noise, or just replacing the Loose Cat..
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
All you gotta do is replace the factory AOS with the UAOS w/ Track Drain and you can not only run full oil (8.5 qts), but you can actually overfill it with up to 2 quarts over full (10.5 qts) using the UAOS Track.
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.
Reported cause
I have diagnosed a fixed ( on the internet and in person) several of these with "tapping noises" that everyone suspected was something sinister like Bore-Scoring....when they turned out to be a loose Cat or Carbon Build-up on the Piston Top and a can of CRC Carbon Remover cured the Tapping noise, or just replacing the Loose Cat..
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.
40 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 · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T191851Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Welcome to the madness of 996 ownership! These are great machines. Make sure to check in with questions and comments. A lot of smart people available here.
Get a Stethoscope and listen to the Cats !!!! .....You may be lucky and the tapping be a Cat falling apart and not "bore-scoring".....
Would be the "steal of the month" ...
Wow, some sharp-eyed commenters on the Cars and Bids site have realized that the car is sitting on Ohlins coilovers. They also pointed out than it has an IMS Solution installed too. That�s
a lot
of car for your money�
I want to recommend you purchase an
oil analysis test kit
to test the motor oil before you change it or take any extended drives on the car. Hopefully it will give you a glimpse into the condition within the motor.
Hope the OPs car turns out to be a easy fix�
But just because I�m curious and I would jump on a 996 like the OP for $11k� let�s say it does have some nasty bore scoring. What would it look like if I filled it up with some heavier oil and just ran the thing? Presumably it would continue to worsen and you would see oil consumption and smoking, probably not great for the cats� but it�s a $11k car so swap them out for some bypass pipes ignore the CEL. What would be the terminal result? Piston rings eventually get chewed up and it starts blowing some serious smoke? Not saying it�s a good idea to just run the motor to destruction but at the same time not everyone has $20k+ to redo an M96.
Whats the cheapest way to keep a car on the road once the engine is toast? My impression from reading some threads is a used Boxster engine was the least expensive swap to keep it Porsche�. But I also see some talk of Audi, Honda or LS swaps. What�s the most straightforward option?
Thanks for the help guys, I am going to do the test kit. Some of the engineers from rennline and my place of work are going to look it over when it gets delivered. I can afford to do the motor but I don't want to do it this winter. It ended up being 13051 with shipping, which even if it only makes it to my garage and never runs I'm ok with it.
I paid $33k delivered for a 37k mile 996 in June and then dropped just shy of $7k for IMS (never been done), Clutch/flywheel, AOS, water pump and a few other things. Fortunately it turned out to have a clean bill of health with regard to bore scoring. It�s nice to have a well sorted car but I can�t say I could resist a deal like yours, particularly seeing things like that 400+ HP turbo Honda motor in a recent thread that really have me thinking about picking up another 996.
Look forward to seeing how things go with this car of yours.
Looks like a great find! The smoke on start-up could be a failing AOS, easy to test with a manometer. I find it common on 3.4L cars to have some lifter ticking on start-up, it's worth checking. If you ever hear a car with heavy bore score I find it more of a tapping noise than a ticking noise. Unless someone scrubbed the exhaust tips heavily I don't see a lot of soot build up so you might be lucky!
Great find!
The smoke on the start up can be too much oil. If your car have the original oil dipstick, it should not be filled full. Also the dash oil measure indicator should be kept reading 2-lines below the full line.
There's are several good instructions on the web how to set the correct oil level. Porsche also provided a service bulletin to this several years ago.
Here's oil level instructions from LN Engineering website (free download) to M96 engines:
https://lnengineering.com/free-downl...-and-1515.html
The reason for this is the poorly designed factory AOS.
All you gotta do is replace the factory AOS with the UAOS w/ Track Drain and you can not only run full oil (8.5 qts), but you can actually overfill it with up to 2 quarts over full (10.5 qts) using the UAOS Track. In addition, you can also run the UAOS Track plus a 2 qt Deep Sump and run a total of 12.5 quarts of oil.
Remember this, the M96 requires lots of high quality fresh oil to keep it running strong. It does not like oil starvation.
Let me get this straight. The car has almost no recorded service in the Carfax. It was acquired by the seller last month and the first thing he did was to try and get it to stop burning oil so he replaced the AOS, spark plugs and O2 sensors. When that didn't do it, he put it up on cars and bids. There is no reason he would have replaced those items unless it had been burning oil. And there is a tapping sound? I don't think this will end well.
The OP may have gotten a heck of a deal.
$13,000 purchase price
-5,000 Ohlins + Labor
-3,000 LN Solution + Labor
$ 5,000 Net Purchase Price
Add in engine rebuild for $30k, you have a $52k cost for $43k that will run like a champ. Who knows, maybe there are additional pleasant surprises with other parts that have been refreshed.
I like this deal if the OP has the $30k for a rebuild.
For sure.
The reality is the cheaper the purchase price, the more neglect and the more you are going to have to put into the car for a refresh.
Whether we like it or not, every 996 will end up costing its owner $30k in refresh items (engine, suspension, exhaust, exterior and interior) unless you buy a car that is well sorted. Plus another $30k for an engine rebuild someday off in the future. Same for any other desirable classic sports car from any other manufacturer. Unfortunately, we can't defy mechanical wear and plastic/rubber breakdown on any 25 year old car.
But I'm not complaining. I paid top dollar for my 996.2 23 years ago and have refreshed it 2x. Its just too much damn fun driving it on the street and track.
Based on the green resto that just sold on bat for 90k this seems like a great buy - lots of $�s left to build what you want. I�d have bought it for that fist full of dollars. If I was paying attention
This is not necessarily true. I paid $17,500 for a 2000 Millenium Edition Coupe Manual in Jan 2025, with original paint, no accident history and about 85% of its ownership history was with one owner in California. It had a documented engine rebuild, full suspension refresh, AC component replacement, window regulators, all sorts of stuff over the years. All documented with a stack of records, most of which were from one German specialist shop in CA. It was anything BUT neglected. The catch? It had over 150k miles. So the interior needs new leather on the seats and the wood trim is cracking, but the car is mechanically sound and its my daily driver. So it was the high mileage that brought the price down, not any sort of neglect or needing major mechanical repair. Admittedly, thats kind of the exception to the rule. The problem is most of the 996s were not driven
enough
, so they are due for lots of work. I think one of the best buys in classics right now is not just a 996, but a high mileage 996 that has had a lot of the work done and you can just buy it, drive the wheels off of it and enjoy it. I actually think the high mileage cars are even "cooler". It adds a bit of soul and character to the car. The more mileage a car has, the more "street cred" it has. LOL
Sounds like you got a good one! Congrats!
I am unapologetically a 996 enthusiast that wants to see these things well maintained and on the road. They really are exceptional drivers cars on the street and track.
But to your point, the key is to do the right things to the engine to keep it running in top form. They can go many, many hundreds of thousand miles. Even better if a buyer can find one from an owner that did just that.
The easy stuff to do it the exhaust, suspension, interior and exterior refresh stuff. Still costs alot of money, but nobody want a beautiful paperweight sitting in their garage with an engine that is shredded from neglect. Same thing can be said for any classic Porsche, Ferrari, Aston, Lamborghini, etc.
Its all about taking care of the engine.
The selling dealer did state: "tapping sound and smoking on start up" would be a cause of concern for me. But for $11k what can you expect. Those comments could mean several different things but you won't know until you dive into it. Looking at the pictures, it appears to be in decent shape. Will need love but what 25 year old car doesn't. Could be a fun project. I would recommend doing a bore scope, cam deviation reading, etc. so you know what you're dealing with. Welcome to the world spending money on a depreciating asset! LOL. Don't ask me how I know :P)
To everyone PooPooing on this car remember, this is a 2000 3.4 that has Iron Plated Pistons and Dual Row IMSB....So Bore-Score and IMSB failure are much less a concern... ( but a head crack/intermix is more common on these models Nick-named the the Y2K Syndrome)
I have diagnosed a fixed ( on the internet and in person) several of these with "tapping noises" that everyone suspected was something sinister like Bore-Scoring....when they turned out to be a loose Cat or Carbon Build-up on the Piston Top and a can of CRC Carbon Remover cured the Tapping noise, or just replacing the Loose Cat..
But isn't speculating on someones elses fortune fun !!!!!
Whoa! good deal for a runner. That leaves enough money for getting into engine and fixing what needs fixing. Good thing I stopped looking at CnB and BaT or I'd be divorced.
Hoping for the best on this car. It looks very nice. Post a start up video when you get a chance.
PT3- As I am another proud owner of a happy 3.4, what is it about these cars that predisposes them to cracked heads?
Well the issues stems from the core philosophy of Porsche, where they use "Engineering" as the foundation of their "Performance Matrix " in designing their cars...
They love to save weight to enhance the power/weight ratio of all Porsche's ...
I love to do the same thing as in my daily driver for 1.5 decades back in the 80's, my daily driver Street Car I built had a 5.8 lbs/HP ratio that not many cars achieve even today...as an example my 996 has a ratio of about 10.0 lbs/HP ....( 3000lbs/300HP)
I remember being in PorcheTraning Class and the Instructor bragging about Porsche saving a few grams weight with a new designed Vario-Cam Actuator.....lol
Anyway I can tell by looking closely at the castings of the heads and block that they were designed to use a "minimum" of metal molten aluminum in the castings to keep weight as low as possible...but in doing so also means that any warpage from hot spots or overheating is more likely to find a sharp edge to start forming a crack.....( like around the spark plug holes) .. This is why I mentioned in my "Internal Mods/Tips/Tricks Thread" about radiusing all sharp edges of the engine, especially the Spark Plug Holes ...
The Sharp Edge of the spark plug holes is where the crack starts to form on the 3.4 engines...(the 996.2 3.6 up engines have a different design around the spark plug holes)
The car has aftermarket header's and muffler from the looks of it and not cat's. Its actually way louder than I thought it would be. I had my friend who is a engineer at rennline look it over, he said it had a new water pump but there was a lot of missing hardware in the engine bay. I'll post a cold start it doesn't smoke really much anymore and he said they all kinda sound like that.
