15 captured repliesPartial discussion capture · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHPossible rebuild
Reported or suspected cause
carbon build up in the heads
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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0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Leading evidence: 'carbon build up in the heads' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'carbon build up in the heads' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Replace cooling system functioning perfectly' (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 performed work without a confirmed outcome
1
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Performed · outcome unconfirmed
Millers 10/50 regularly changed, cooling system functioning perfectly with an LTT.
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Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
However, operators with large fleets and therefore a lot of overhauls and hence a lot of data have found that leaving it on wing to the Manufaturers limit means that when you strip it down, more parts are beyond economic repair and need to be replaced with new or good second hand.
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
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Suggestion
Oil analysis every oil change, oil change with good oil at least every year, look for changes in the oil analysis.
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
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Suggestion
I change my oil in my car 3 times a year after rebuilt due to bore scoring and always warm my engine up to temp before i drive..
Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
However, operators with large fleets and therefore a lot of overhauls and hence a lot of data have found that leaving it on wing to the Manufaturers limit means that when you strip it down, more parts are beyond economic repair and need to be replaced with new or good second hand.
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.
15 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
911uk: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
1 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
My leggy boxster is on 160k miles now with no change in oil analysis and nothing in the filter, ever.
Oil change tomorrow and I'll be sending it for an oil analysis. Car runs perfect and other than the obvious Porsche paranoia that afflicts us all I don't fret too much about it. It's done 89k, I do the oil twice a year and it has been well serviced previously. Following some recent posts, discussions and photos I am considering a rebuild, mostly thinking the crank and bearings will be the weakness on a 3.4. I'm guessing that new bearings and that it would be prudent to upgrade the ims to the Porsche later design. What sort of money is this likely to be? Has anyone done this kind of thing, ie preventative with no cylinder work
Yeah, his car seems to keep on going and going. I'm waiting to see what the oil spec says. My one thought been does it make it a less worrying drive when taking out.
I'm going to post my opinion here .. i'm sure many people won,t agree but it's what i think ...
I don't feel that every engine when it hits 90 - 100K needs a rebuild .. i see many past this with no problems .. if it aint broke then don't fix it .
You may be unlucky .. people at 30K have been unlucky .
if you want to do this then who am i to argue .. but i don't like people throwing money at a problem when there isn't a problem .
if you drive it for another 50k and the crank turns out to be shot then isn't there a short block that fixes that ..
Hartech rebuild .. bless them ..huge respect .. it's about future problems .. a short Porsche block .. well , even if it's the same as the original will give you another 80 K plus ... it has the newer IMS though .
My feeling is and always has been to save you guys money .. that's why i come here night after night .
Im sure there will be comments but as always i will post what i think and leave it at that .
Good luck either way .
The 3.4 is likely to go on forever as long as you look after it like you do with oil changes. The only parts which would be a possible worry are the cam chain guides which can (and do) wear out. Just have your indie keep looking it over (properly) every oil change and you're good. No point doing a rebuild for rebuild's sake, unless you have money to burn. If that's the case, I have some great snake oil over here you might like to buy... :grin:
I take that point on board demort, £5k for a short block direct from Porsche does seem like an appropriate route depending on when they run out of stock!
Ive never heard of chains snapping on any 911, changing them would be a waste if doing that only!! I change my oil in my car 3 times a year after rebuilt due to bore scoring and always warm my engine up to temp before i drive..
J
I work in commercial aviation - as I'm sure others on here do too - so my analogy is this -
On the 737-800 the Nose Landing Gear has an overhaul schedule of 10 years or 18,000 cycles (landings) - which ever comes first.
However, operators with large fleets and therefore a lot of overhauls and hence a lot of data have found that leaving it on wing to the Manufaturers limit means that when you strip it down, more parts are beyond economic repair and need to be replaced with new or good second hand. This drives up the cost considerably and therefore some large operators have determined (based on their data) that 16,000 cycles is the sweet spot to remove the nose landing gear for overhaul. Will the landing gear fail if you leave it on longer up to the OEM limit - no.
I liken Hartech to a large operator. They have a lot of data. From reading Baz's Posts over the years, his philosophy (based on data) seems to be that the sweet spot to rebuild a M96 is 100k miles as that is the point where most parts are reworkable. Does it mean if you don't do it that it will fail - no. Does it mean if you do it at 120k it will be more expensive - not necessarily.
The data just tells a story. Hence I agree with Demort and also with Hartech!
I've seen this twice on Caymans .. one was due to carbon build up in the heads .. i'm afraid i never worked out what caused this issue and i spent an hour or two looking at adaption figures and actual values trying to figure it out .
Parts do indeed wear out .. do you pre-emit it and get a rebuild done .. or do you wait till there is a failure .. possibly many miles in the distance .. that is what this is all about and there is no answer .. things fail , nothing lasts forever .. but at what point do you start spending money .. there is imho no answer to this question .
monitor .. look for metal in the filter .. perhaps get an oil inspection done . i know nothing about this btw and see .. or have a rebuild . i don't have an answer im afraid .
I just post what i feel ... but Porsche state ... whether true or not .. it's a small percentage that fail .
Oil analysis every oil change, oil change with good oil at least every year, look for changes in the oil analysis. Chain guides in the heads can be done at very low cost, it is when you split the bottom end that the costs go up very quickly.
Infrasilver is the man to give a good idea of rebuild costs.
MC
^^^^ This.
Millers 10/50 regularly changed, cooling system functioning perfectly with an LTT. Then just an oil analysis every change.
Yes there's still the small risk of D chunking etc but how much risk do we need to try and dial out our lives? And at what cost?
A preventative rebuild could mean you're wasting thousands of pounds when your engine may have performed perfectly for another 100k miles.
Utter madness in my eyes but that's just my opinion and everyone has one. :thumb:
I think it boils down to how we, as individuals, deal with risk. Some of us just deal with stuff as and when (if) it happens others want peace of mind and pre-empt things that 'may' happen.
I have a slightly different take on this in that I'm currently looking for a 3.2 M96 boxster engine to strip and rebuild. One with a ruined IMS would be perfect, as would most failures as long as the crank is likley to be ok.
My leggy boxster is on 160k miles now with no change in oil analysis and nothing in the filter, ever. The big end bearings won't last forever though and whilst she's running well with lots of miles on I intend to find a motor, rebuild it myself (plus/minus increasing capacity) and then put it into my 20 year old Boxster which will probably then outlive me.
My main reason for doing this is not preventative maintenance, its so I can learn to rebuild the engine myself. The car is my hobby and the expense is worth it to me just for this alone.
:thumb:
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