996-997 wet-sump engine reliability: enter your stats here!
Discussion
They are very good value for money now - especially as still relatively few fail.
More important than that is the fact that when rebuilt they can avoid the reoccurence of the faults (demonstrating that they were not so major that they could not have been fixed much earlier - but were minor design failings that were actually easy to fix if the problem was properly identified - something Porsche seem blind to).
Bearing in mind we offer a warranty maintenance scheme that protects owners against the full cost of that rebuild - I still think they are fantastic value for money - if you protect your investment or can afford a rebuild.
As proof of this - amongst the many cars and failed engines we now get in for repair are the first ones with no faults - just coming in for future proofing, fixing the weak spots and protecting the owners future pleasure and reliability - so buyers are beginning to see the benefits set against the prices and driving pleasure and coming up with the answers we proposed as inevitable a few years ago now.
The basic weak areas are the IMS seal and sometimes too tight a bearing fit, the open deck design (which we alter to the closed deck now much publicised as the best way to make an engine by Porsche themselves and featured in the Gen 2 engines), the low coolant relative flow in the cylinder block (that can be modofied) and the high set thermostat (which we replace with a lower temp one).
I know people get annoyed at me harping on about these things - but if some would give credit where it is I think (with all due modesty) - due - we did correctly identify (and bravely publicise in our buyers guide) that open deck weakness and find a fix for it years ago, correctly predict gradual ovaility of the block as a result, came up with a single repair liner solution, identify the actual cause of the IMS bearing failures (the silly seal) and invest heavily in solutions that all worked out perfectly - and we shouldn't get knocked for that when clearly the might of German Engineering failed to do so for years.
Still great cars - inexpensive enough to justify some protection or even pre-planned maintenance to avoid more expensive failures later.
Baz
More important than that is the fact that when rebuilt they can avoid the reoccurence of the faults (demonstrating that they were not so major that they could not have been fixed much earlier - but were minor design failings that were actually easy to fix if the problem was properly identified - something Porsche seem blind to).
Bearing in mind we offer a warranty maintenance scheme that protects owners against the full cost of that rebuild - I still think they are fantastic value for money - if you protect your investment or can afford a rebuild.
As proof of this - amongst the many cars and failed engines we now get in for repair are the first ones with no faults - just coming in for future proofing, fixing the weak spots and protecting the owners future pleasure and reliability - so buyers are beginning to see the benefits set against the prices and driving pleasure and coming up with the answers we proposed as inevitable a few years ago now.
The basic weak areas are the IMS seal and sometimes too tight a bearing fit, the open deck design (which we alter to the closed deck now much publicised as the best way to make an engine by Porsche themselves and featured in the Gen 2 engines), the low coolant relative flow in the cylinder block (that can be modofied) and the high set thermostat (which we replace with a lower temp one).
I know people get annoyed at me harping on about these things - but if some would give credit where it is I think (with all due modesty) - due - we did correctly identify (and bravely publicise in our buyers guide) that open deck weakness and find a fix for it years ago, correctly predict gradual ovaility of the block as a result, came up with a single repair liner solution, identify the actual cause of the IMS bearing failures (the silly seal) and invest heavily in solutions that all worked out perfectly - and we shouldn't get knocked for that when clearly the might of German Engineering failed to do so for years.
Still great cars - inexpensive enough to justify some protection or even pre-planned maintenance to avoid more expensive failures later.
Baz
Has anyone here seen a rebuilt-by-Porsche engine in the last couple of years? Or carefully compared the Porsche-supplied replacement items to the originals?
Are we to assume that these engines will always require rebuilds every <60K-ish miles if the replacement components are of the exact same quality/spec/materials as the original that failed?
Are there any clear patterns emerging regarding Porsche-upgraded-component failure? I ask as an OPC stated that my 2006 Cayman S has a later, modified, IMS and associated bearing - and that they are not seeing any IMS-related failures with these later types.
Like others my car's bore lining seems to have failed (cylinder six) - is a new replacement cylinder block from Porsche exactly the same? I would like to think that, like the IMS issue, Porsche would be supplying improved cylinder linings in their replacement blocks.
If the block linings are the same as the originals surely rebuilding will be a constant cycle for these engines, no?
Likewise are the shells improved now? The rod bolts? etc...
Is it being suggested here that Porsche still have not sorted these potential materials/manufacturing/design/quality problems out and that, perhaps, only the likes of Hartech can rebuild these engines in such a way that they won't require being rebuilt yet again every xK miles?
Are we to assume that these engines will always require rebuilds every <60K-ish miles if the replacement components are of the exact same quality/spec/materials as the original that failed?
Are there any clear patterns emerging regarding Porsche-upgraded-component failure? I ask as an OPC stated that my 2006 Cayman S has a later, modified, IMS and associated bearing - and that they are not seeing any IMS-related failures with these later types.
Like others my car's bore lining seems to have failed (cylinder six) - is a new replacement cylinder block from Porsche exactly the same? I would like to think that, like the IMS issue, Porsche would be supplying improved cylinder linings in their replacement blocks.
If the block linings are the same as the originals surely rebuilding will be a constant cycle for these engines, no?
Likewise are the shells improved now? The rod bolts? etc...
Is it being suggested here that Porsche still have not sorted these potential materials/manufacturing/design/quality problems out and that, perhaps, only the likes of Hartech can rebuild these engines in such a way that they won't require being rebuilt yet again every xK miles?
In answer to the question "will these engines need replacement every 60K" firstly you have to be comparing like for like. Some drivers care and style hardly strains such an engine at all and rarely drive really hard, at high revs or over 90mph. Others find a thrash around the Nurbergring acceptable (as one of our rebuilt units did recently).
But - on everage - the earlier cars seem to reach an average rebuild need at around 80K and the facelift and later nearer 60K. This does not mean there are not exceptions (some considerable) but then there are also some failing below 20K -so it balances out.
The later IMS is better (mainly because the bearing and housing are thicker - so resist too much compression when the fits are tight) but the overheating of the cylinder wall and corresponding frequency of scored cylinder bores and pistons - is worse/sooner - so one improvement and a matching new failure.
The new block seems to me the same - so should provide similar life expectancy.
Rebuilt engines by us address some of the problems we know about. We run the cylinders cooler, improve further the IMS lubrication, and restrict the gradual ovality of the cylinders - all will help - but then some issues we cannot do so much about - e.g. the crankshaft shell bearings. They are narrower than previous similar engines and this means that as the clearances wear bigger they will not support the bearings as well as they used to. By running the engines cooler and recommending a thicker oil grade we expect to improve this lifespan too but we cannot achieve miracles with an engine designed (I think) for a shorter lifespan than older versions - and ours costs about half that of a new engines (and has guarantees etc provided).
We are not sure about the Lokasil bores - they seem to us to be OK and should last a long time once they are restrained from going oval, but the composite nature of the surface may degrade with time - we are testing this and keeping records and so far it all seems OK but we do know how to improve the surface life and presently are testing different options (more later).
In our experience - people who can afford brand new Porsche's (and perhaps up to 5 years old) tend to fall into two distinct majority categories - some abusing the engines unmercifully - not bothered with the consequences as it is guaranteed, warranted, not their car or they can afford it to go wrong and of course more careful restrained drivers.
As they age the proportions of buyers of older versions that are careful - tend to increase and the annual mileages reduce until at 10 or 12 years old there are very few abusing the engines - so as they wear out more - they are less strained - which helps.
It all makes statistics very difficult to analyse - but they are great cars and it seems to me unlikely that an engine rebuilt with modifications to improve the weakspots will be worse than one exactly the same as the one that failed - that costs twice as much - and if you consider the lighter life they usually experience later on - that combination seems to me to make a Hartech rebuild better value for money - but it will not convert one of these engines into the level of reliability the older Porsche engines once enjoyed - that is beyond achieving given the basic changes in design and costs/profits generated.
Baz
But - on everage - the earlier cars seem to reach an average rebuild need at around 80K and the facelift and later nearer 60K. This does not mean there are not exceptions (some considerable) but then there are also some failing below 20K -so it balances out.
The later IMS is better (mainly because the bearing and housing are thicker - so resist too much compression when the fits are tight) but the overheating of the cylinder wall and corresponding frequency of scored cylinder bores and pistons - is worse/sooner - so one improvement and a matching new failure.
The new block seems to me the same - so should provide similar life expectancy.
Rebuilt engines by us address some of the problems we know about. We run the cylinders cooler, improve further the IMS lubrication, and restrict the gradual ovality of the cylinders - all will help - but then some issues we cannot do so much about - e.g. the crankshaft shell bearings. They are narrower than previous similar engines and this means that as the clearances wear bigger they will not support the bearings as well as they used to. By running the engines cooler and recommending a thicker oil grade we expect to improve this lifespan too but we cannot achieve miracles with an engine designed (I think) for a shorter lifespan than older versions - and ours costs about half that of a new engines (and has guarantees etc provided).
We are not sure about the Lokasil bores - they seem to us to be OK and should last a long time once they are restrained from going oval, but the composite nature of the surface may degrade with time - we are testing this and keeping records and so far it all seems OK but we do know how to improve the surface life and presently are testing different options (more later).
In our experience - people who can afford brand new Porsche's (and perhaps up to 5 years old) tend to fall into two distinct majority categories - some abusing the engines unmercifully - not bothered with the consequences as it is guaranteed, warranted, not their car or they can afford it to go wrong and of course more careful restrained drivers.
As they age the proportions of buyers of older versions that are careful - tend to increase and the annual mileages reduce until at 10 or 12 years old there are very few abusing the engines - so as they wear out more - they are less strained - which helps.
It all makes statistics very difficult to analyse - but they are great cars and it seems to me unlikely that an engine rebuilt with modifications to improve the weakspots will be worse than one exactly the same as the one that failed - that costs twice as much - and if you consider the lighter life they usually experience later on - that combination seems to me to make a Hartech rebuild better value for money - but it will not convert one of these engines into the level of reliability the older Porsche engines once enjoyed - that is beyond achieving given the basic changes in design and costs/profits generated.
Baz
What is the favorite repair methodolgy for oval bores on these units? I would with just one potential issue want all the mods carried out what sort of figure would a full rebuild and mod programme cost Baz?,using a scored bore as a starting point not a broken crank ect.
If (as some do) these are overbored it concerns me regarding the weakness already in the bottom of the engine at std cc and output on already quite a stressed unit.
G
If (as some do) these are overbored it concerns me regarding the weakness already in the bottom of the engine at std cc and output on already quite a stressed unit.
G
Gary, prices depend upon what customers want and what is also neccessary, but a typical scenario of an undamaged engine requiring a re-fresh and all the various upgrades like IMS bearing, new chains and runners, re-round cylinders and alter to a closed deck design, cylinder head overhauls and a new oil separator, new crank bearings, gaskets and seals, modify coolant flow and low temperature thermostat, oil change and new coolant etc - from receiving the car to giving it back finished and road tested comes to just under £5K + Vat. Many do not need all those mods or parts.
Another option is to join our Maintenance Plan so if the engine failed the repair would only cost for parts (not labour) and be a fraction of that cost.
Even less expensive would be to buy from us (when the engine will already be fully checked and serviced, guaranteed (and the Lifetime Maintenance Plan payments are lower).
Baz
Another option is to join our Maintenance Plan so if the engine failed the repair would only cost for parts (not labour) and be a fraction of that cost.
Even less expensive would be to buy from us (when the engine will already be fully checked and serviced, guaranteed (and the Lifetime Maintenance Plan payments are lower).
Baz
We have developed a method of re-rounding the cylinders that is our secret. We cannot always get them 100% perfect but can reduce the ovality from the usual 4 to 10 thou to about 0-2 thou (which is only +/- 1 thou out of round and a superb improvement). The lower the ovality we start out trying to improve the closer we get to the right size but we cannot risk going the other way and being oval the other way so we can only get close - but most new crankcases actually also already have ovality of around the same amount (due to stress relieving of the casting after machining) so what we achieve is probably as close as it is possible to get to a new cylinder anyway. Sometimes with a very poor cylinder that is say 10 to 12 thou oval - we can only get to about 2 to 3 thou - but this is such an improvement most customers notice the sharper acceleration and reduced consumption that follows.
We then fit a restraining ring to hold the cylinder in its new shape, effectively converting the block to a closed deck design.
Our new alternative (currently undergoing very successful tests that include track use) is slightly oversized pistons that enable us to fit the restraining rings first and then open out the bore to a perfect oversize and perfectly round.
We have had to invest heavily (tens of thousands) in this to achieve the right surface finish of the Lokasil cylinder bores (involving solid diamond tools, special honing machine, electronic surface finish tester and very high resolution and magnification electronic microscope). This was found neccessary to test the roughness or smoothness of the silicon particles embedded in the matrix and create the right level of exposure and smoothing of the chrystal edges without loosening the chrystals too much so they fall out of the matrix prematurely (extremely challenging and complicated). All this to prevent high oil consumption and premature Molycote wear.
The associated test engines had to be built, run, assessed, stripped (and some discarded) replaced with different alternatives etc until we got the understanding we needed to reliably reproduce the finish required. We tried harvesting enough technical information from the World's leading spoecialists on the subject but found responses misleading or innacurate - often on pressing their initial confident responses with conclusions they eventually admitted they didn't actually know what to do themselves because re-machining Lokasil is not generally undertaken successfully anywhere else.
However - we have persevered because this new alternative reduces the overall cost and is a better solution but (unlike some of our competitors) we do not offer new solutions to general sale before thorough testing (even though it is an expensive process after investing in it and then waiting to recover costs) and then we have to order a larger quantity of special pistons (to achieve the prices that are competitive) so we are not yet ready to offer this as a general solution - more testing to do and miles to cover but it is not too far away.
Although machining out oversized will reduce the wall thickness the inclusion of restraining rings more than compensates.
The main problem unrestrained is that the whole wall thickness of the cylinder is made up of about 50% Lokasil and 50% aluminium. The Lokasil is less stable and prone to creep over time and heat and stress cycles but is an excellent surface material if properly created with the right surface finish.
I too regard the whole engine as designed more for its purpose than previous Porsche engines (many of which you could happily double the torque and bhp output with inpunity). It makes financial and technical sense to only design an engine to handle the intended use and the result is a lighter, faster and more ecconomical engine than making one far stronger than it ever needed to be in normal use - but costing too much to manufacture. However the resulting reduction in the strength of con rods, and crankshaft, the reduced crankshaft shell bearing widths, and the higher running temperatures (to reduce emmissions) all contrbute to an overall assessment that would discourage me from trying to make a more powerful version during the rebuild (for which purpose Porsche returned to the original stronger design and charged the extra accordingly - Turbo and GT3 versions).
Next season we intend to replace our existing two sponsored 968 race cars (currently lying 2nd and 4th) with a Boxster (same engine crankshaft etc) as a means of testing these various solutions more quickly uunder more severe conditions.
Baz
We then fit a restraining ring to hold the cylinder in its new shape, effectively converting the block to a closed deck design.
Our new alternative (currently undergoing very successful tests that include track use) is slightly oversized pistons that enable us to fit the restraining rings first and then open out the bore to a perfect oversize and perfectly round.
We have had to invest heavily (tens of thousands) in this to achieve the right surface finish of the Lokasil cylinder bores (involving solid diamond tools, special honing machine, electronic surface finish tester and very high resolution and magnification electronic microscope). This was found neccessary to test the roughness or smoothness of the silicon particles embedded in the matrix and create the right level of exposure and smoothing of the chrystal edges without loosening the chrystals too much so they fall out of the matrix prematurely (extremely challenging and complicated). All this to prevent high oil consumption and premature Molycote wear.
The associated test engines had to be built, run, assessed, stripped (and some discarded) replaced with different alternatives etc until we got the understanding we needed to reliably reproduce the finish required. We tried harvesting enough technical information from the World's leading spoecialists on the subject but found responses misleading or innacurate - often on pressing their initial confident responses with conclusions they eventually admitted they didn't actually know what to do themselves because re-machining Lokasil is not generally undertaken successfully anywhere else.
However - we have persevered because this new alternative reduces the overall cost and is a better solution but (unlike some of our competitors) we do not offer new solutions to general sale before thorough testing (even though it is an expensive process after investing in it and then waiting to recover costs) and then we have to order a larger quantity of special pistons (to achieve the prices that are competitive) so we are not yet ready to offer this as a general solution - more testing to do and miles to cover but it is not too far away.
Although machining out oversized will reduce the wall thickness the inclusion of restraining rings more than compensates.
The main problem unrestrained is that the whole wall thickness of the cylinder is made up of about 50% Lokasil and 50% aluminium. The Lokasil is less stable and prone to creep over time and heat and stress cycles but is an excellent surface material if properly created with the right surface finish.
I too regard the whole engine as designed more for its purpose than previous Porsche engines (many of which you could happily double the torque and bhp output with inpunity). It makes financial and technical sense to only design an engine to handle the intended use and the result is a lighter, faster and more ecconomical engine than making one far stronger than it ever needed to be in normal use - but costing too much to manufacture. However the resulting reduction in the strength of con rods, and crankshaft, the reduced crankshaft shell bearing widths, and the higher running temperatures (to reduce emmissions) all contrbute to an overall assessment that would discourage me from trying to make a more powerful version during the rebuild (for which purpose Porsche returned to the original stronger design and charged the extra accordingly - Turbo and GT3 versions).
Next season we intend to replace our existing two sponsored 968 race cars (currently lying 2nd and 4th) with a Boxster (same engine crankshaft etc) as a means of testing these various solutions more quickly uunder more severe conditions.
Baz
Globs said:
ASR1 said:
2002 996 C4S
75,000 miles when bought
Kept for 1 year
77,000 miles when sold
No engine issues (thank God) - but would never buy another
Just out of interest why would you never buy another? TIA!75,000 miles when bought
Kept for 1 year
77,000 miles when sold
No engine issues (thank God) - but would never buy another
Come on, we're all starting to agree now. Barry is right they are pretty good value and we all agree on the shoddy practice by Porsche. I'm looking to buy another one at the moment and Hartech are inspecting it on Wednesday. Lovely convertible, original 17 inch wheels, amber lights, metropole hood and seats and arctic (?) silver paint. I'll drive it to Spain at once. Wonking! Meet for coffee, BCNRML?
hi all. I am confiscating the computer from my husband who is far too obsessed with this website and has now interrupted a nice family evening with yet another hour of perusing the pistonheads website.....I will relinquish the computer within 24 hours once we have purchased some essential curtain rails and curtains from Jean Louis tomorrow. Also, he needs to contact a man about a porsche which looks like it has our name on it so he had better not let it go. Apologies for this non-technical contribution.
Best
Anaesthetist
Best
Anaesthetist
I sometimes wonder if it would have been better to separate the various postings and issues to a whole new topic - just to be read by people who (1) have an existing engine problem - (2) think they may have an existing engine problem - or (3) are the type of person who wants to find a reliable Warranty/Maintenance Plan that he is prepared to pay for (and can afford) to stop him worrying about his engine going wrong - and that then states "WARNING NOT TO BE READ BY ANYONE ELSE OF A NERVOUS DISPOSITION" - because failures are still very rare - but such a dissaster - only for people in those categories.
I know I get accused of scare mongerring for business sake - but I know my own motivation and I know that technically and as an engineer - a lot more are going to go wrong in the future (as they age and mileages increase plus owners change) and that it can be a financial and confidence sapping dissaster if the only option people are offered is a new engine at £12K or more - while I can offer a less expensive alternative.
However we have also come up with ways of making a rebuild less likely to go wrong again and indeed - in the case of the low temperature thermostat (and advice about oil grades etc) - may even be able to reduce the incidence of failures (or extend the life) of newer versions like the 3.6, 3.8 and Cayman S engines.
So while it would be easy to discriminate between the upper three categories to prevent worrying those that don't presently have a problem - from having their pleasure spoilt - it would be impossible to advise those with newer cars (that are running perfectly OK right now) - how to extend the average reliability - without informing them of the potential problem and consequences.
Without the additional advantages of feedback - confirming that those who achieve longer mileages seem to be the ones that warm up their cars well before driving fast, change their oil more often (and perhaps also gradually change to slightly thicker grades as the engine wears) - more would find themselves in the former three categories when they might have avoided it alltogether.
So - in defence of my position - I cannot find an alternative that is in owners interests other than to inform them about potential problems and solutions - but I do recognise that some people are much more sensitive to the wider issues of confidence than me (being a typical engineer for whom engines are just pieces of metal that need to be sorted out when they go wrong) and I cannot find a simple answer to how to achieve the best outcome for both categories of owner - except perhaps to just put a warning at the beginning of such postings for those that prefer to burry their heads in the sand until they need help.
Baz
I know I get accused of scare mongerring for business sake - but I know my own motivation and I know that technically and as an engineer - a lot more are going to go wrong in the future (as they age and mileages increase plus owners change) and that it can be a financial and confidence sapping dissaster if the only option people are offered is a new engine at £12K or more - while I can offer a less expensive alternative.
However we have also come up with ways of making a rebuild less likely to go wrong again and indeed - in the case of the low temperature thermostat (and advice about oil grades etc) - may even be able to reduce the incidence of failures (or extend the life) of newer versions like the 3.6, 3.8 and Cayman S engines.
So while it would be easy to discriminate between the upper three categories to prevent worrying those that don't presently have a problem - from having their pleasure spoilt - it would be impossible to advise those with newer cars (that are running perfectly OK right now) - how to extend the average reliability - without informing them of the potential problem and consequences.
Without the additional advantages of feedback - confirming that those who achieve longer mileages seem to be the ones that warm up their cars well before driving fast, change their oil more often (and perhaps also gradually change to slightly thicker grades as the engine wears) - more would find themselves in the former three categories when they might have avoided it alltogether.
So - in defence of my position - I cannot find an alternative that is in owners interests other than to inform them about potential problems and solutions - but I do recognise that some people are much more sensitive to the wider issues of confidence than me (being a typical engineer for whom engines are just pieces of metal that need to be sorted out when they go wrong) and I cannot find a simple answer to how to achieve the best outcome for both categories of owner - except perhaps to just put a warning at the beginning of such postings for those that prefer to burry their heads in the sand until they need help.
Baz
A genuine question that I havent seen answered.
I read much about 'less than 5%' are affected by these problems. My question is, will all of these engines eventually have the IMS, D-chunk and bore scoring issues or are only a small amount destined to ever have them?
In other words, are these failures ultimately inevitable, given time.
MTR
I read much about 'less than 5%' are affected by these problems. My question is, will all of these engines eventually have the IMS, D-chunk and bore scoring issues or are only a small amount destined to ever have them?
In other words, are these failures ultimately inevitable, given time.
MTR
In answer to the question will they all have a failure of the IMS, D chunk or cylinder scoring - I can only guess as follows from knowledge base so far.
2.5 and 2.7 Boxster.no, no, no (because after about 60K the IMS seems OK
3.2 Boxster S no, no, no (as above plus bores thicker and better cooling).
3.4 996 no, yes, Maybe (as above plus thinner bores eventually go oval and D chunk). Maybe because if it doesn't D chunk the extra clearance (and resulting blow by) may eventually cause cylinder scoring.
3.4 Cayman S no, eventually, yes (because IMS seems better, scoring seems inevitable one day and if not it will probably eventually D chunk.
£.6 996, £.6 997 and 3.8 997 no, eventually, yes.
There will be a mileage at which generally chains and crankshaft bearings fail - probably nearer 80 to 100K for the 3.8 and getting longer as the engine size reduces back to a 2.5 Boxster. Mainly mileages typical of most modern engines.
Air/oil separators will all fail (until they make the diaphragm of different material or re-design it) - leading to smoking at tickover.
Boxster S and 3.4 996's eventually cracked heads or core plug failure - perhaps 150 K plus.
Other failure points - Random at any time - crank bearing failure from blocked oil feed holes, worn top chain runners (up to 996 3.4).
Hope this answers the question.
Baz
2.5 and 2.7 Boxster.no, no, no (because after about 60K the IMS seems OK
3.2 Boxster S no, no, no (as above plus bores thicker and better cooling).
3.4 996 no, yes, Maybe (as above plus thinner bores eventually go oval and D chunk). Maybe because if it doesn't D chunk the extra clearance (and resulting blow by) may eventually cause cylinder scoring.
3.4 Cayman S no, eventually, yes (because IMS seems better, scoring seems inevitable one day and if not it will probably eventually D chunk.
£.6 996, £.6 997 and 3.8 997 no, eventually, yes.
There will be a mileage at which generally chains and crankshaft bearings fail - probably nearer 80 to 100K for the 3.8 and getting longer as the engine size reduces back to a 2.5 Boxster. Mainly mileages typical of most modern engines.
Air/oil separators will all fail (until they make the diaphragm of different material or re-design it) - leading to smoking at tickover.
Boxster S and 3.4 996's eventually cracked heads or core plug failure - perhaps 150 K plus.
Other failure points - Random at any time - crank bearing failure from blocked oil feed holes, worn top chain runners (up to 996 3.4).
Hope this answers the question.
Baz
hartech said:
In answer to the question "will these engines need replacement every 60K" firstly you have to be comparing like for like. Some drivers care and style hardly strains such an engine at all and rarely drive really hard, at high revs or over 90mph. Others find a thrash around the Nurbergring acceptable (as one of our rebuilt units did recently).
But - on everage - the earlier cars seem to reach an average rebuild need at around 80K and the facelift and later nearer 60K. This does not mean there are not exceptions (some considerable) but then there are also some failing below 20K -so it balances out.
The later IMS is better (mainly because the bearing and housing are thicker - so resist too much compression when the fits are tight) but the overheating of the cylinder wall and corresponding frequency of scored cylinder bores and pistons - is worse/sooner - so one improvement and a matching new failure.
The new block seems to me the same - so should provide similar life expectancy.
Rebuilt engines by us address some of the problems we know about. We run the cylinders cooler, improve further the IMS lubrication, and restrict the gradual ovality of the cylinders - all will help - but then some issues we cannot do so much about - e.g. the crankshaft shell bearings. They are narrower than previous similar engines and this means that as the clearances wear bigger they will not support the bearings as well as they used to. By running the engines cooler and recommending a thicker oil grade we expect to improve this lifespan too but we cannot achieve miracles with an engine designed (I think) for a shorter lifespan than older versions - and ours costs about half that of a new engines (and has guarantees etc provided).
We are not sure about the Lokasil bores - they seem to us to be OK and should last a long time once they are restrained from going oval, but the composite nature of the surface may degrade with time - we are testing this and keeping records and so far it all seems OK but we do know how to improve the surface life and presently are testing different options (more later).
In our experience - people who can afford brand new Porsche's (and perhaps up to 5 years old) tend to fall into two distinct majority categories - some abusing the engines unmercifully - not bothered with the consequences as it is guaranteed, warranted, not their car or they can afford it to go wrong and of course more careful restrained drivers.
As they age the proportions of buyers of older versions that are careful - tend to increase and the annual mileages reduce until at 10 or 12 years old there are very few abusing the engines - so as they wear out more - they are less strained - which helps.
It all makes statistics very difficult to analyse - but they are great cars and it seems to me unlikely that an engine rebuilt with modifications to improve the weakspots will be worse than one exactly the same as the one that failed - that costs twice as much - and if you consider the lighter life they usually experience later on - that combination seems to me to make a Hartech rebuild better value for money - but it will not convert one of these engines into the level of reliability the older Porsche engines once enjoyed - that is beyond achieving given the basic changes in design and costs/profits generated.
Baz
But - on everage - the earlier cars seem to reach an average rebuild need at around 80K and the facelift and later nearer 60K. This does not mean there are not exceptions (some considerable) but then there are also some failing below 20K -so it balances out.
The later IMS is better (mainly because the bearing and housing are thicker - so resist too much compression when the fits are tight) but the overheating of the cylinder wall and corresponding frequency of scored cylinder bores and pistons - is worse/sooner - so one improvement and a matching new failure.
The new block seems to me the same - so should provide similar life expectancy.
Rebuilt engines by us address some of the problems we know about. We run the cylinders cooler, improve further the IMS lubrication, and restrict the gradual ovality of the cylinders - all will help - but then some issues we cannot do so much about - e.g. the crankshaft shell bearings. They are narrower than previous similar engines and this means that as the clearances wear bigger they will not support the bearings as well as they used to. By running the engines cooler and recommending a thicker oil grade we expect to improve this lifespan too but we cannot achieve miracles with an engine designed (I think) for a shorter lifespan than older versions - and ours costs about half that of a new engines (and has guarantees etc provided).
We are not sure about the Lokasil bores - they seem to us to be OK and should last a long time once they are restrained from going oval, but the composite nature of the surface may degrade with time - we are testing this and keeping records and so far it all seems OK but we do know how to improve the surface life and presently are testing different options (more later).
In our experience - people who can afford brand new Porsche's (and perhaps up to 5 years old) tend to fall into two distinct majority categories - some abusing the engines unmercifully - not bothered with the consequences as it is guaranteed, warranted, not their car or they can afford it to go wrong and of course more careful restrained drivers.
As they age the proportions of buyers of older versions that are careful - tend to increase and the annual mileages reduce until at 10 or 12 years old there are very few abusing the engines - so as they wear out more - they are less strained - which helps.
It all makes statistics very difficult to analyse - but they are great cars and it seems to me unlikely that an engine rebuilt with modifications to improve the weakspots will be worse than one exactly the same as the one that failed - that costs twice as much - and if you consider the lighter life they usually experience later on - that combination seems to me to make a Hartech rebuild better value for money - but it will not convert one of these engines into the level of reliability the older Porsche engines once enjoyed - that is beyond achieving given the basic changes in design and costs/profits generated.
Baz
hartech said:
In answer to the question will they all have a failure of the IMS, D chunk or cylinder scoring - I can only guess as follows from knowledge base so far.
2.5 and 2.7 Boxster.no, no, no (because after about 60K the IMS seems OK
3.2 Boxster S no, no, no (as above plus bores thicker and better cooling).
3.4 996 no, yes, Maybe (as above plus thinner bores eventually go oval and D chunk). Maybe because if it doesn't D chunk the extra clearance (and resulting blow by) may eventually cause cylinder scoring.
3.4 Cayman S no, eventually, yes (because IMS seems better, scoring seems inevitable one day and if not it will probably eventually D chunk.
£.6 996, £.6 997 and 3.8 997 no, eventually, yes.
There will be a mileage at which generally chains and crankshaft bearings fail - probably nearer 80 to 100K for the 3.8 and getting longer as the engine size reduces back to a 2.5 Boxster. Mainly mileages typical of most modern engines.
Air/oil separators will all fail (until they make the diaphragm of different material or re-design it) - leading to smoking at tickover.
Boxster S and 3.4 996's eventually cracked heads or core plug failure - perhaps 150 K plus.
Other failure points - Random at any time - crank bearing failure from blocked oil feed holes, worn top chain runners (up to 996 3.4).
Hope this answers the question.
Baz
Thanks for responding with all of this useful info Baz. The outlook for owners seems somewhat bleak tbh.2.5 and 2.7 Boxster.no, no, no (because after about 60K the IMS seems OK
3.2 Boxster S no, no, no (as above plus bores thicker and better cooling).
3.4 996 no, yes, Maybe (as above plus thinner bores eventually go oval and D chunk). Maybe because if it doesn't D chunk the extra clearance (and resulting blow by) may eventually cause cylinder scoring.
3.4 Cayman S no, eventually, yes (because IMS seems better, scoring seems inevitable one day and if not it will probably eventually D chunk.
£.6 996, £.6 997 and 3.8 997 no, eventually, yes.
There will be a mileage at which generally chains and crankshaft bearings fail - probably nearer 80 to 100K for the 3.8 and getting longer as the engine size reduces back to a 2.5 Boxster. Mainly mileages typical of most modern engines.
Air/oil separators will all fail (until they make the diaphragm of different material or re-design it) - leading to smoking at tickover.
Boxster S and 3.4 996's eventually cracked heads or core plug failure - perhaps 150 K plus.
Other failure points - Random at any time - crank bearing failure from blocked oil feed holes, worn top chain runners (up to 996 3.4).
Hope this answers the question.
Baz
I was mis-informed regarding Porsche using different part numbers for replacement parts for these issues - the part numbers are exactly the same as originally specified.
I'm now told "It might be that some of the parts are modified but with the same part number or maybe sourced by Porsche from different suppliers." there are a lot of maybes in this last point yet it may be of significance if certain failures have been due to materials and/or manufacturing/QA issues.
I'm also told "We have not had any reoccurring problems on any of the engines we have changed or rebuilt." but this latter statement may well be due to insufficient mileage on these rebuilt units...
Anyway many thanks for taking the time for such detailed responses Baz!
I think I'll start a new thread (so as not to distract this one) regards your comments on engine abuse.
Sorry about having the caps lock on - obviously £.6 should read 3.6 etc.
Regarding part numbers - we have found a lot of changes inside engines that we would have only ever spotted due to the large numbers we process.
Many are improvements - but some were tried for a short period and then changed back to the original or some new version. Most had no change to part numbers or identified anywhere else where we can find as different.
Typical examples (not exhaustive) would be crankshaft shells and substrate material specification, crank carrier design (ommiting the heavy metal inserts), crankshaft shell retaining lug positions, cylinder head bolt head size, Numerous changes to IMS bearing housing, bearing and carrier plates etc, etc. All this makes it very hard for us while we try and determine the causes of the failures we see and predict the numbers we anticipate failing.
The nature of failures is such that after a relativley small sample number it should be possible to obtain general statistics that fall into the normal category of statistical analysis and an expected typical scatter gram. But with so many other changes and of course - most important of all - the totally different driving styles and weather conditions encountered (together with different qualities of service and repair) it is extremely hard for us to generalise on expectations.
Probably a better guide was the original opinion I had when I first stripped one of these engines - when I questioned the quality of design of the IMS system, the expected weakness of the open deck design, the potential out of alignment of the RMS and the overhanging crankshaft drive end. My conclusion then was that "someone was going to be very busy repairing these as they age - why don't we start solving the problems and setting up to handle it in quantity - so we can provide the best answers technically and the best value through early investment".
I was also puzzled by the good quality and longevity in the design of some other aspects (like the crank carrier inserts) that were expensive to produce yet only justifyable if the engines were intended to have a long life - while some other parts seemed destined for a short one.
Anyway we took a typical business gamble on the weakness of the engines and invested time and money before the numbers started piling in and were proven right. We manufactured patterns, set up production, experimented with clearances and cooling systems and balance, tested different crankshaft bearings - in fact all sorts of things not yet made available.
I recall - at the time - discussing this with another well known independent specialist who had just moved their future investment from repairs to sales while we went in completley the other direction.
Right now we are investigating ways to increase our storage space and methods and continuing to invest in equipment to complete our - already impressive - engineering workshop transformation - into a fully blown in house engine repair facility with our own valve grinding and possibly crankshaft grinding equipment. Risky I know - as we are talking a lot of money - but our strategy has proven right so far and we trust our judgement.
Perhaps the only mistake we have made is assuming that Porsche would have done something to improve the cylinder stability and cooling capability of the larger engines made since around 2003 onwards - and expected to see numbers stabilising - whereas - it seems - they introduced a new problem of scoring (that if it doesn't affect your engine may still suffer D chunk later) and in so doing numbers failing sooner at lower mileages have exceeded our expectations and we are now working hard to catch up on increasing our physical capacity - to cope with demand.
All this recent activity in a year when we also supported 2 drivers in the Porsche Club Championship (for the first time) has made it hectic - but rewarding (presently in 2nd and 4th positions).
In business you have to invest early if you are to be sure of attracting sufficient business to provide a return - but having done so - competitors trying to follow suit - can only now anticipate ever only getting a small proportion of the market and so I doubt can ever justify trying to compete - job done.
However - despite all this - the type of failures in some areas (and resulting statistics) are still difficult to understand technically and we continue to analyse and test out new and different solutions before offering them to the general retail market.
Some problems we have only seen once (and therefore put down to material or build quality, poor driving or maintenance) but when we first become aware that a problem is likely to repeat (or have already worked out it's technical frailty) - we alwys try and find, test and impliment a solution as quickly as possible - so each engine type incorporates enough solutions - to cover all eventualities - as soon as possible. Logically that can only ever happen after a few rebuilds of each different failure type - but at least we don't simply supply a repeat of the same (as a new engine does) and seem able to quickly find reliable answers.
Logistically we have to test some new solutions in customers cars (we simply cannot find the time or money to build several of each type/age/version/engine size and pay someone to drive them around under test until satisfied) but in these cases it is with the customers full knowledge and approval - and I would like to thanks all those that take part - without which others would wait longer for us to include them or may never be able to do so.
Meanwhile tests on our new scored cylinder bore solution are going very well now that we have found out through trial, error (and considerable new investment) how to achieve the right cylinder bore surface finish through more sophisticated equipment.
Just to reassure the sceptics about our intentions when revealing these details - the investment has already paid off and we have a full order book (and since every year that passes sees more cars of an age and mileage to suffer) we are unlikely to need any more publicity about our provision (thankfully supported by many happy customers on the Internet) and only provide such details to reasure those with problems and try and solve the technical issues while giving some idea what to expect (without upsetting too many existing owners).
This topic heading is "996 and 997 wet sump engine reliability" and it would seem to me that it would be sadly short of content if our small contribution was not included.
Baz
Regarding part numbers - we have found a lot of changes inside engines that we would have only ever spotted due to the large numbers we process.
Many are improvements - but some were tried for a short period and then changed back to the original or some new version. Most had no change to part numbers or identified anywhere else where we can find as different.
Typical examples (not exhaustive) would be crankshaft shells and substrate material specification, crank carrier design (ommiting the heavy metal inserts), crankshaft shell retaining lug positions, cylinder head bolt head size, Numerous changes to IMS bearing housing, bearing and carrier plates etc, etc. All this makes it very hard for us while we try and determine the causes of the failures we see and predict the numbers we anticipate failing.
The nature of failures is such that after a relativley small sample number it should be possible to obtain general statistics that fall into the normal category of statistical analysis and an expected typical scatter gram. But with so many other changes and of course - most important of all - the totally different driving styles and weather conditions encountered (together with different qualities of service and repair) it is extremely hard for us to generalise on expectations.
Probably a better guide was the original opinion I had when I first stripped one of these engines - when I questioned the quality of design of the IMS system, the expected weakness of the open deck design, the potential out of alignment of the RMS and the overhanging crankshaft drive end. My conclusion then was that "someone was going to be very busy repairing these as they age - why don't we start solving the problems and setting up to handle it in quantity - so we can provide the best answers technically and the best value through early investment".
I was also puzzled by the good quality and longevity in the design of some other aspects (like the crank carrier inserts) that were expensive to produce yet only justifyable if the engines were intended to have a long life - while some other parts seemed destined for a short one.
Anyway we took a typical business gamble on the weakness of the engines and invested time and money before the numbers started piling in and were proven right. We manufactured patterns, set up production, experimented with clearances and cooling systems and balance, tested different crankshaft bearings - in fact all sorts of things not yet made available.
I recall - at the time - discussing this with another well known independent specialist who had just moved their future investment from repairs to sales while we went in completley the other direction.
Right now we are investigating ways to increase our storage space and methods and continuing to invest in equipment to complete our - already impressive - engineering workshop transformation - into a fully blown in house engine repair facility with our own valve grinding and possibly crankshaft grinding equipment. Risky I know - as we are talking a lot of money - but our strategy has proven right so far and we trust our judgement.
Perhaps the only mistake we have made is assuming that Porsche would have done something to improve the cylinder stability and cooling capability of the larger engines made since around 2003 onwards - and expected to see numbers stabilising - whereas - it seems - they introduced a new problem of scoring (that if it doesn't affect your engine may still suffer D chunk later) and in so doing numbers failing sooner at lower mileages have exceeded our expectations and we are now working hard to catch up on increasing our physical capacity - to cope with demand.
All this recent activity in a year when we also supported 2 drivers in the Porsche Club Championship (for the first time) has made it hectic - but rewarding (presently in 2nd and 4th positions).
In business you have to invest early if you are to be sure of attracting sufficient business to provide a return - but having done so - competitors trying to follow suit - can only now anticipate ever only getting a small proportion of the market and so I doubt can ever justify trying to compete - job done.
However - despite all this - the type of failures in some areas (and resulting statistics) are still difficult to understand technically and we continue to analyse and test out new and different solutions before offering them to the general retail market.
Some problems we have only seen once (and therefore put down to material or build quality, poor driving or maintenance) but when we first become aware that a problem is likely to repeat (or have already worked out it's technical frailty) - we alwys try and find, test and impliment a solution as quickly as possible - so each engine type incorporates enough solutions - to cover all eventualities - as soon as possible. Logically that can only ever happen after a few rebuilds of each different failure type - but at least we don't simply supply a repeat of the same (as a new engine does) and seem able to quickly find reliable answers.
Logistically we have to test some new solutions in customers cars (we simply cannot find the time or money to build several of each type/age/version/engine size and pay someone to drive them around under test until satisfied) but in these cases it is with the customers full knowledge and approval - and I would like to thanks all those that take part - without which others would wait longer for us to include them or may never be able to do so.
Meanwhile tests on our new scored cylinder bore solution are going very well now that we have found out through trial, error (and considerable new investment) how to achieve the right cylinder bore surface finish through more sophisticated equipment.
Just to reassure the sceptics about our intentions when revealing these details - the investment has already paid off and we have a full order book (and since every year that passes sees more cars of an age and mileage to suffer) we are unlikely to need any more publicity about our provision (thankfully supported by many happy customers on the Internet) and only provide such details to reasure those with problems and try and solve the technical issues while giving some idea what to expect (without upsetting too many existing owners).
This topic heading is "996 and 997 wet sump engine reliability" and it would seem to me that it would be sadly short of content if our small contribution was not included.
Baz
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