Definitive Word on IMS
Discussion
I should have added that if Porsche charged the price for the 993 that recovered the same profit margins to survive that they have built into the 996/997/Cayman range - the 993 would have been very much more expensive. Better quality in the engine area - yes - more expensive - also yes and is so if needing a rebuild (fortunately usually after longer mileages).
Mr Orange Curry - you shouldn't mock those with less to spend - the 993 is not such a good drive and more expensive to fix usually.
Baz
Mr Orange Curry - you shouldn't mock those with less to spend - the 993 is not such a good drive and more expensive to fix usually.
Baz
Off topic...
I couldn't resist championing the 1990s 964-block engineers, that is all.
hartech said:
Mr Orange Curry - you shouldn't mock those with less to spend
No mocking intended (and what has money got to do with it?)I couldn't resist championing the 1990s 964-block engineers, that is all.
hartech said:
the 993 is not such a good drive and more expensive to fix usually.
Baz
Really? I guess we are all different. Like many others, I prefer the more connected 'feel' of the older cars.Baz
hartech said:
Snip
Yeah that was the price I took from the website.Seems reasonable.
Only asking as I'm looking at what car to get in the next 2 years when my Scirocco project is finished. Toying up the idea of a Coxster/Boxster S or 911 of some kind.
My landlord was also looking at buying a Boxster S but IMS issues put him off so he bought a new Golf Carbio (???)
We are aware of three different sources of shells and some we have tested that were not manufactured for this model ( and some not for this make) and have tested them and the ones we now use are the best. Even parts now supplied by Porsche appear to be different than those in many of the original engines and seem better quality.
We would not like to reveal exact details to our competitors -sorry,
Baz
We would not like to reveal exact details to our competitors -sorry,
Baz
but this makes me smile
A.G. said:
anonymous said:
[redacted]
But I have a finite amount to spend. My budget is, as I said 25-30k max. The ridiculous thing is if I want one then you would seem to be saying it would make more sense to buy the most cosmetically perfect car I can find for 15k. It will be 10 grand cheaper than the 25k cars for a reason. Maybe it's got a scabby or non-existent service history, or it has done a million miles, or the engine is broken or about to break, or maybe all of the above. I will then thrash the living daylights out of it until it pings due to whichever one of the aforementioned certain disasters strikes first. I then go to someone like Hartech and get it rebuilt to an acceptible standard with the 10k I saved and now have a better 25k minter than the actual 25k minter that has not yet, but is about to grenade itself.
With every other performance car I have bought, I have always used the "Buy the best one you can afford." doctrine. Porsche seemed to have turned this on it's head here. Buy a bad one cheap and make it right for the price of a supposedly good one.
With a performance car, I can live with high maintenance, silly parts prices and stratospheric main dealer labour rates. It's all part of the game with this type of car and I'm well used to it. Furthermore there is usually some way around it with indies and aftermarket parts manufacturers etc.
It may sound illogical but however much it stings, I have much less of an issue with being handed a 3k bill for 3k's worth of parts and labour for a labour intensive job on a complex car because I know thats what needs doing than spunking 3k on some failure that has become commonplace at a time soon enough for it to be hardly fit for purpose.
I also accept engines can have achilles heels. I've owned a few. Stag - overheating issues. K-Series HGF, RS Pinto - clattery cam, Speed Six - finger followers, BMW - VANOS, RX-7 etc. You get the drift. None of which however are usually immediately catastrophic. The other thing in common with them all is they each only had one achilles heel.
The more I think about it, the 15k plan may actually be the sensible one.
Somewhat unusually for this forum - some really sensible and reasonable conclusions reached by many = progress!
Cmoose is right to point out that the main issue will be bore scoring and we have previously confirmed that you can usually drive them for many miles and months after it has started.
The big difference is that the previous air cooled and 944/968 liquid cooled models may have occasionally failed due to small issues but during a rebuild most everything else can just be put back together again. You could do that with these but measuring will reveal changes that would significantly shorten the rebuild mileages unless that problem was addressed during the rebuild - requiring not only replacement cylinders - but essentially by a method that supports the new cylinders sufficiently well to stop them either going oval or becoming loose. It is a fact that most liner replacements (ferrous and alloy Nikasil) do nothing to support the new liner.
It is a well established engineering principle that to successfully fit a liner into a cylinder block both the liner and the tube remaining in the cylinder block must be equally strong enough not to distort or become loose (don't take my word for it - research this on the Internet (say Wikepedia etc) and you will find independent confirmation). If the original cylinder was not strong enough to resist going oval then boring it out to fit a liner will only make it even weaker and so with this "open deck" design it is essential to support the top of the new cylinder in a precision machined recess (something we have not found anyone else doing but ourselves - but that we did right from the outset over 12 years ago). Research will also establish that a supported wet liner replacement is the most reliable and strongest replacement system (which ours is) and this is even confirmed by the technical documents available from the original M96/97 crankcase manufacturers.
The point about bore ovality and cracking is that it is continually deteriorating and in so doing increases cylinder bore clearances (and therefore "blow by") which increasingly overheats the piston face and burns the oil on the piston (evidential on strip down).
Pistons also have to be made to expand without seizing when flat out (which few ever achieve for more than a few seconds) so normally run "loose" anyway.
All this means that unlike previous Porsche engines there is something that needs fixing during a rebuild for a continuous long life afterwards and a supported alloy Nikasil plated wet liner (i.e. Hartech system) is the best solution.
We have also previously explained why the thermostat being in the engine entry position combined with a greatly reduced (but very unusual and since abandoned in later models) share of the coolant being directed into the cylinder area - can combine to lead to significant heat soak and raised cylinder temperatures (hence reduced oil film thickness) in some circumstances.
Ironically cold ambients can make this worse while hotter ones can keep the thermostat more open longer and actually help. A LTT keeps the thermostat open earlier and longer also and therefore assists in correcting this anomaly (but is not a complete fix - just something to help).
High torque is low to medium revs and full throttle openings. You do not get this when revving an engine high or round a track (usually never at full throttle until over 5K revs out of corners or the tyres will skid) and to test and prove this we raced for 2 seasons with Lokasil bores with no problems (although that was only covering perhaps 1000 miles overall and with new pistons and rings fitted - and we had also fitted "support rings" to support the top of the original cylinders and keep them round and increased the coolant flow into the cylinder block). This testing of internal engine temperatures on road and track, combined with experienced technical engineering capability helped us work out what was going on and why things failed.
The most difficult question to answer in these circumstances is why some engines fail and not others. With previous models it would be why did one incident occur and that is usually due to tolerances and manufacturing or material differences that all engineered products exhibit. Not just so with bore scoring because the continual pressure from the piston against the Lokasil surface weakens the bond between the silicon particles and the substrate. The rate at which this releases particles and their distribution in the matrix influences whether just one particle or several close together get released at the same time.
When loose particles are released they rub between the piston and the cylinder wall until they either escape in the oil or sometimes knock another piece (probably becoming more loose than it used to be) out to join it before it escapes and this can lead to a viscous circle which in a few seconds can result in more and more creating a cluster, knocking more and more pieces loose until they cannot escape, stick to the piston (especially where there is coating loss) and wreck the bore and the piston face.
After than there is extra clearance just there (all be it combined with higher oil consumption and eventual knocking) so further silicon loss does not continue to make things worse for a long time.
So bad scoring relates to how much torque has been used over the years, the anbient temperatures, the driving style and the random distribution (and bond quality) of silicon within the original Lokasil matrix = unpredictable failures.
What is certain is that deterioration is a continual process (if not an accurately predictable failure point) and because it can be permanently cured by the very same solution Porsche themselves have used successfully in the GT3 and Turbo versions (a closed deck Nikasil alloy cylinder) the obvious solution is to permanently fix that problem either when the engine needs rebuilding (for any reason), decide to do it when fixing the IMS problem permanently or simply to fix it all before a big failure results to preserve as many parts as possible for use during the rebuild.
Prices make this a worthwhile consideration and although some have had a new engine fitted under warranty (and I agree is likely to last several tens of thousands of miles afterwards) the cost of being on that scheme long enough to cover that possibility would usually more than cover the cost of the alternative of having the engine rebuilt with technical changes that remove that eventual repetition failure all together! And if on our Maintenance Plan - costing far less over several years than paying Porsche prices for wear and tear replacements to preserve the eligibility for their cover.
Baz
Cmoose is right to point out that the main issue will be bore scoring and we have previously confirmed that you can usually drive them for many miles and months after it has started.
The big difference is that the previous air cooled and 944/968 liquid cooled models may have occasionally failed due to small issues but during a rebuild most everything else can just be put back together again. You could do that with these but measuring will reveal changes that would significantly shorten the rebuild mileages unless that problem was addressed during the rebuild - requiring not only replacement cylinders - but essentially by a method that supports the new cylinders sufficiently well to stop them either going oval or becoming loose. It is a fact that most liner replacements (ferrous and alloy Nikasil) do nothing to support the new liner.
It is a well established engineering principle that to successfully fit a liner into a cylinder block both the liner and the tube remaining in the cylinder block must be equally strong enough not to distort or become loose (don't take my word for it - research this on the Internet (say Wikepedia etc) and you will find independent confirmation). If the original cylinder was not strong enough to resist going oval then boring it out to fit a liner will only make it even weaker and so with this "open deck" design it is essential to support the top of the new cylinder in a precision machined recess (something we have not found anyone else doing but ourselves - but that we did right from the outset over 12 years ago). Research will also establish that a supported wet liner replacement is the most reliable and strongest replacement system (which ours is) and this is even confirmed by the technical documents available from the original M96/97 crankcase manufacturers.
The point about bore ovality and cracking is that it is continually deteriorating and in so doing increases cylinder bore clearances (and therefore "blow by") which increasingly overheats the piston face and burns the oil on the piston (evidential on strip down).
Pistons also have to be made to expand without seizing when flat out (which few ever achieve for more than a few seconds) so normally run "loose" anyway.
All this means that unlike previous Porsche engines there is something that needs fixing during a rebuild for a continuous long life afterwards and a supported alloy Nikasil plated wet liner (i.e. Hartech system) is the best solution.
We have also previously explained why the thermostat being in the engine entry position combined with a greatly reduced (but very unusual and since abandoned in later models) share of the coolant being directed into the cylinder area - can combine to lead to significant heat soak and raised cylinder temperatures (hence reduced oil film thickness) in some circumstances.
Ironically cold ambients can make this worse while hotter ones can keep the thermostat more open longer and actually help. A LTT keeps the thermostat open earlier and longer also and therefore assists in correcting this anomaly (but is not a complete fix - just something to help).
High torque is low to medium revs and full throttle openings. You do not get this when revving an engine high or round a track (usually never at full throttle until over 5K revs out of corners or the tyres will skid) and to test and prove this we raced for 2 seasons with Lokasil bores with no problems (although that was only covering perhaps 1000 miles overall and with new pistons and rings fitted - and we had also fitted "support rings" to support the top of the original cylinders and keep them round and increased the coolant flow into the cylinder block). This testing of internal engine temperatures on road and track, combined with experienced technical engineering capability helped us work out what was going on and why things failed.
The most difficult question to answer in these circumstances is why some engines fail and not others. With previous models it would be why did one incident occur and that is usually due to tolerances and manufacturing or material differences that all engineered products exhibit. Not just so with bore scoring because the continual pressure from the piston against the Lokasil surface weakens the bond between the silicon particles and the substrate. The rate at which this releases particles and their distribution in the matrix influences whether just one particle or several close together get released at the same time.
When loose particles are released they rub between the piston and the cylinder wall until they either escape in the oil or sometimes knock another piece (probably becoming more loose than it used to be) out to join it before it escapes and this can lead to a viscous circle which in a few seconds can result in more and more creating a cluster, knocking more and more pieces loose until they cannot escape, stick to the piston (especially where there is coating loss) and wreck the bore and the piston face.
After than there is extra clearance just there (all be it combined with higher oil consumption and eventual knocking) so further silicon loss does not continue to make things worse for a long time.
So bad scoring relates to how much torque has been used over the years, the anbient temperatures, the driving style and the random distribution (and bond quality) of silicon within the original Lokasil matrix = unpredictable failures.
What is certain is that deterioration is a continual process (if not an accurately predictable failure point) and because it can be permanently cured by the very same solution Porsche themselves have used successfully in the GT3 and Turbo versions (a closed deck Nikasil alloy cylinder) the obvious solution is to permanently fix that problem either when the engine needs rebuilding (for any reason), decide to do it when fixing the IMS problem permanently or simply to fix it all before a big failure results to preserve as many parts as possible for use during the rebuild.
Prices make this a worthwhile consideration and although some have had a new engine fitted under warranty (and I agree is likely to last several tens of thousands of miles afterwards) the cost of being on that scheme long enough to cover that possibility would usually more than cover the cost of the alternative of having the engine rebuilt with technical changes that remove that eventual repetition failure all together! And if on our Maintenance Plan - costing far less over several years than paying Porsche prices for wear and tear replacements to preserve the eligibility for their cover.
Baz
Carlson W6 said:
Some great posts here.
The elephant in the room for me that i keep coming back to when prices are quoted both for secondhand naturally aspirated 997's and repair costs was the 2012/13 crop of secondhand 996 Turbo's with Mezgers at circa £25K and what a great deal they were.
That was exactly my position in 2013.It was a no-brainer then...The elephant in the room for me that i keep coming back to when prices are quoted both for secondhand naturally aspirated 997's and repair costs was the 2012/13 crop of secondhand 996 Turbo's with Mezgers at circa £25K and what a great deal they were.
I picked my 996 up from Hartech today following the 'full works' rebuild. Really can't fault the service and the car drives really well even compared to before. I was definitely lucky on the IMS bearing and bottom end bearings front though. The rest I didn't necessarily need as bore scoring wasn't that bad for 92k miles but it felt like a worthwhile investment given the other work that was required.
LordHaveMurci said:
People have a habit of forgetting that, also forget not all of us want AWD & I can't be the only one that doesn't like the looks?
Well I think sticking a turbo on a sweet engine is a bit like using a condom, albeit probably a ribbed one but none the less rather false and unsatisfactory !!FrankCayman said:
LordHaveMurci said:
I can't be the only one that doesn't like the looks?
I am with you! If the 997 had dropped that low, I'd have snapped one up with cash straight away sparta6 said:
all good info here but it seems there is no definitive answer, apart from taking a punt and keeping £10K in your back pocket just in case.
I'll be getting another 928 instead. I've had 3 relays go in 4.5 years of hard driving, and some new tyres. Granite engineering.
That's not how I've read countless buyers guides on them!I'll be getting another 928 instead. I've had 3 relays go in 4.5 years of hard driving, and some new tyres. Granite engineering.
sparta6 said:
all good info here but it seems there is no definitive answer, apart from taking a punt and keeping £10K in your back pocket just in case.
I'll be getting another 928 instead. I've had 3 relays go in 4.5 years of hard driving, and some new tyres. Granite engineering.
You could easily spend 10k on a 928. Anything expensive and old consumes cash.I'll be getting another 928 instead. I've had 3 relays go in 4.5 years of hard driving, and some new tyres. Granite engineering.
LordHaveMurci said:
That's not how I've read countless buyers guides on them!
Plenty of cheap neglected examples out there as with any tipo. When you speak with owners most have only pleasant experiences with no surprises providing they bought a well maintained one. My 928 costs around 50% less in servicing per year than the 308. Key to 928 ownership is always carry some spare relays. Most gremlins are attributable to a venerable Bosch relay 
or just replace them all in one hit at £8 each..xjay1337 - I have checked the figures and for a Boxster S. Cayman S. 996 or 997 it is for up to 3K/annum £60/month, 10K/annum £86/month and 20K/annum £133/month + Vat.
However I actually did our plan a dis-service when I didn't mention that it not only covers the labour for wear and tear items (yes you only pay for the parts) for most mechanical items (including engines) and most other repairs (except mainly those caused by corrosion, perishing etc) but it also includes both the PARTS and LABOUR for your annual (or mileage related) service (for which incidentally we do not follow the Porsche recommended intervals either - even though it costs us more as a result - by following a maximum or 12K or 12 months between services!
Although this means that anyone on our higher mileage rating (20K) or the 30K one (£187/month + Vat) will have to visit us more than once/annum - it also means they will go through brakes etc at least once every two years (perhaps less), and reach the mileage when clutches and even engines need fixing much sooner.
In practice most are on our once/year service visit because the Porsche warranty is a one off annual payment that does not increase with annual mileage - but you have to pay for your servicing and repairs at full price on top. With ours including the full service costs and labour for repairs - we have to increase our costs if a higher mileage limit is chosen to cover the more frequent servicing and replacement wear and tear repairs.
We have worked through all sorts of examples comparing the full annual costs (including predictable repairs and occasional unpredictable failures like window mechanisms etc) and it works out cheaper on our scheme if you ignore the added benefit of a first class engine rebuild (including future proofing modifications) which is effectively FOC.
It probably works out better value for the low mileage owner than the very high mileage one - since that random statistical risk factor has to come into force more
significantly as mileages increase and especially because we know that many internals in the engines are wearing out at a faster rate than they used to with older models and therefore despite the low statistical numbers failing up to now - they will increase in the future.
Baz
However I actually did our plan a dis-service when I didn't mention that it not only covers the labour for wear and tear items (yes you only pay for the parts) for most mechanical items (including engines) and most other repairs (except mainly those caused by corrosion, perishing etc) but it also includes both the PARTS and LABOUR for your annual (or mileage related) service (for which incidentally we do not follow the Porsche recommended intervals either - even though it costs us more as a result - by following a maximum or 12K or 12 months between services!
Although this means that anyone on our higher mileage rating (20K) or the 30K one (£187/month + Vat) will have to visit us more than once/annum - it also means they will go through brakes etc at least once every two years (perhaps less), and reach the mileage when clutches and even engines need fixing much sooner.
In practice most are on our once/year service visit because the Porsche warranty is a one off annual payment that does not increase with annual mileage - but you have to pay for your servicing and repairs at full price on top. With ours including the full service costs and labour for repairs - we have to increase our costs if a higher mileage limit is chosen to cover the more frequent servicing and replacement wear and tear repairs.
We have worked through all sorts of examples comparing the full annual costs (including predictable repairs and occasional unpredictable failures like window mechanisms etc) and it works out cheaper on our scheme if you ignore the added benefit of a first class engine rebuild (including future proofing modifications) which is effectively FOC.
It probably works out better value for the low mileage owner than the very high mileage one - since that random statistical risk factor has to come into force more
significantly as mileages increase and especially because we know that many internals in the engines are wearing out at a faster rate than they used to with older models and therefore despite the low statistical numbers failing up to now - they will increase in the future.
Baz
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