She''s in at Hartech getting the full £10k rebuild...

bludger said:

Please excuse me but I'm a lurker here but prospective 911 acquirer (997.2 or perhaps 991.1)

Does any one know what the actual failure rate is on these cars? Are there any collective statistics that give this information and the mileage at which the failure occurred?

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Little data to establish the outcome and incidence you seek
Notwithstanding this, even if its a failure rate of 1%, if it happens to you, the failure rate is 100% and will cost you £10k-£12k to put right that does not add anything to the value except perhaps make it easier to sell IF it has had the FULL Hartech treatment.

Then you have to consider the risk your purchase might have if this happens to you. As one other poster stated, if the idea of a £10k bill in such a possibility frightens you, then perhaps you might reconsider buying the 996/997.1 cars if they have not had the full Hartech remedial treatment.
Better then to consider a 997 Gen 2 with a bigger budget.

Note that some cars may have had a new engine under a Porsche warranty.
Sadly, the risk of bore scoring and/or IMS bearing failure is present in such an engine. Hartech have addressed any design flaws where Porsche did not in their replacement engines (other than an updated IMS bearing in later cars).

So the decision is yours and yours alone and risk and how you handle it will probably give you the best guidance as well as a phone call to Grant at Hartech?

bludger said:

Please excuse me but I'm a lurker here but prospective 911 acquirer (997.2 or perhaps 991.1)?

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Sounds to me like you are only considering 997.2 and up, rather than older 996/997.1 so much of the above advice (though great) doesn't apply. 8)

Generally, the 997.2 cars aren't considered as troublesome due to the redesign. Unless you're Phil. Then you swear a lot and get a rebuild anyway. :floor:

N.B. Ask Phil for a video of him bouncing off the limiter in the Dinslakken sound off competition :grin: :grin: :grin:

DrJimBone said:

bludger said:

Please excuse me but I'm a lurker here but prospective 911 acquirer (997.2 or perhaps 991.1)?

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Sounds to me like you are only considering 997.2 and up, rather than older 996/997.1 so much of the above advice (though great) doesn't apply. 8)

Generally, the 997.2 cars aren't considered as troublesome due to the redesign. Unless you're Phil. Then you swear a lot and get a rebuild anyway. :floor:

N.B. Ask Phil for a video of him bouncing off the limiter in the Dinslakken sound off competition :grin: :grin: :grin:

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Have I missed something is Phil's definitely a rebuild?

I'm not sure what stage he's at but last time I spoke to him we did some man maths over a cuppa and worked out that it would probably be work the few extra grand over 'an investigate and rebuild' vs a 'Hartech investigate and rebuild', both due to speed of Baz's team in turning it around and in future value in a for sale ad.

Mine had a rebuild from a place in Wales which I thought was good enough when I bought it. Lasted all of 6k before it shat itself.

Anyway, I headed offshore after that chat and haven't had any update since...

Phil? :dont know:

No updates yet still waiting for a oil sample analasys from Hartech this will help us understand if its missing due to a fault in the map or DME or if theres actually something broken in the engine like a tappet housing or valve cover or something the tricky issue is that you can drive the car under 3800 revs and its fine indicating that its not mechanical as soon as you go over 3800RPM at the point where the timing map changes it develops a missfire with no codes other than which cylinder is missing .So the question thats got us stumped is 1/ is the dme or map corrupted at the point where the timing map changes or is there something like a broken part that only shows its face when the timing changes and becomes longer . Me not understanding what happens to componants when the timing map changes at around 3800 rpm doesnt help me try and explain ,but if some somponants move further this could indicate its sticking or being affected by another damaged component. So Tuesday its going to the OPC to have the original maps reflashed back on the car this will either solve it or we can scratch the map as the issue off our list which will then leave us with a faulty DME or something broken in the engine in which case it could potentially be a rebuild dependant on what secondry damaged has been caused by the part that failed. its at that point that I would have to consider how much I was into versus how much extra to get a hartech rebuild with their modified liners .sadly their 4ltr upgrade for the gen2 isnt ready yet so they said I cant have it, as that was the first thing I asked them. :grin: :grin: clearly I would prefer not to have to spend another 10k this year on top of the 8k already spent this year so will be looking at options as and when they become clearer whats needed . :thumb:

I presume this relates to Variocam Plus and changes to the intake cam timing and lift. It's meant to relate to various factors that are measured rather than activate at specific RPM.

Magic919 said:

I presume this relates to Variocam Plus and changes to the intake cam timing and lift. It's meant to relate to various factors that are measured rather than activate at specific RPM.

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Yes I am guessing your right ,and its just a coincidence that it cuts in at around those RPM, the variocam has been discussed several times but everyone thinks it would generate a code if it was that . but nothing can be disscounted at present. :thumb: :thumb:

Morning All,

LOL I posted this - had a big weekend and forgot I'd posted it and just logged on to see if any comments..... Plenty I see :thumb:

It's crap Luck. I was gutted when I took the call - as many of you know I bought it 12 months ago and had the full IMS check done. BUT Grant at Hartech said that doesn't matter, it can be clean at time of check and happen any time that - so literally ANY TIME!

That said:

- I've had one 993 and two 996s and they have been great. It's the 997 that's let me down

- I want to own a Porsche 911 but don't want to spend £70-80k on a new one. In fact I wanted to spend £30k. So I bought a 10yr old car. The risks come with it I guess. ALTERNATIVE - buy a sensible new car !!!! That just doesn't appeal to me.... my mates got a Defender, his engine just blew up, £9 grand!
Got to be pragmatic sometimes....

- If I sell it, what would I get ???? Nothing else ticks the boxes apart for another expensive car which Comes with same or worse risks. What - an Aston???? LOL it would be 2x the cost at least.

Still gutted but HOPEFULLY once it's done, it's done and I've got a rock solid 911?!?!?!?

I'll re-read all comments again and have a think on what I should also get done...

Nice one gents

Dan :thumbs:

911DG said:

my mates got a Defender, his engine just blew up, £9 grand!
Got to be pragmatic sometimes....

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Yep, I've got a LR Discovery, my second one as the first one snapped its crank ('common' problem in the 3.0 V6 engine according to the forums) leaving me with an £18k bill to get the car back on the road, I ended up part-exing it at Land Rover for a new one with a full warranty.

Porsche aren't the only cars that go wrong, and they're not actually that expensive to fix compared to Land Rovers!

Dan, when Hartech have your engine out, dismantled and inspected they will give you a call to talk you through what needs doing and all the options. They will advise you what must be done, what would be sensible to do while the engine is out, corroded coolant pipes etc. and other things you might choose to have done while the engine out.

They sent me pictures of all the things that I needed to make a decision on and their advice was spot on.

My engine was rebuilt last April and i have covered about 8000 miles since, now it's well run in it feels fantastic, really strong and smooth, it's a lot of money, but if you plan to keep the car for any length of time, I think it will be a good investment!

Just to clarify a few points.

The Porsche engines do not have liners (too expensive to make 2 parts when one casting will do).

The original 944, 968 models had Alusil cylinder blocks cast in aluminium with a high concentration of silicon which comes out of solution over 13% when the balance grows silicon nodules evenly spaced in the matrix. These then form the hard surface points for the cylinder bore - but the downside is that it is everywhere in the cylinder block and makes machining it slow, hard work and costly.


M96/7 engines also have no liners and have a one piece cylinder block casting but because they needed to improve profitability at that time the idea was formed to concentrate silicon only where it is needed at the bore area (so the remaining machining would be faster and cheaper) by creating a porous preformed tube of silicon particles held in suspension by binders. The idea was for molten aluminium to permeate the pre-form under very high casting pressure but that needed metal casting moulds so prevented sand cores creating passageways in the cylinder block for oil and coolant etc.

The result was a clever design needing a separate crankshaft cassette. For the early Boxsters it worked fine as long as the pistons had a hard iron coating to resist the hardness of the silicon particles (as with Alusil).


Making the engine bigger within the same cylinder pitch and block height meant that coolant space suffered between the larger bores and the 996 3.4 compromised by making the cast cylinder wall thinner - when it became weak and over a long period of time some cracked.


Then the hard iron coating process was (we understand) banned in Europe for health and safety issues resulting in a plastic piston coating that was not as good and several eventually scored bores especially when they made the capacity and with it the loads on the cylinder to piston interface even higher. To make the cylinder stiffer they changed the concentration of silicon in the pre-form but that resulted in bigger silicon particles which caused more damage against the plastic piston coating if they became lose.


At the time the more expensive GT3 and turbo models did fit alloy liners with Nikasil bore coatings (the same coating used for years for air cooled 911's with great reliability) - more expensive but practically fool proof.


Machining out the bore bigger to fit thinner liners into a thinner tube (iron or aluminium) that is already too thin results in 2 tubes with less stiffness and so dry liners (as they are called) can be difficult to stop moving about and can sink (leading to head sealing problems) or rotate or tilt and this is obviously one of the reasons manufacturers rarely use them.


We completely machine out the whole of the original liner at the top and fit a new solid alloy cylinder with a Nikasil coating (very similar to the more expensive but completely reliable GT3 and turbo systems). We also machine the top of the inside of the block to receive the top hat of our new cylinder to convert the construction to a closed deck for rigidity. Our cylinders have external ribs (to increase surface area for better cooling) and don't need an interference fit to locate - so there are no difficulties with differential expansion or contraction during heating and cooling cycles and being alloy they maintain closer bore clearacnes throught the whole engine temperature cycles which increases compression and reduces emmisions.


So Porsche do not use liners, some replacement alternatives do and ours are not liners but new cylinders. We only call then liners since the public at large are generally not interested in reading the above explanation and seem to understand the word liner better. For clarity ours are probably closer to be called "wet liners" as the coolant touches the outside of them directly.


Having a solid cylinder also transfers heat better than two tubes (one inside the other) which are dry liners.

The Gen 2 has returned to the older 944/968 reliable and proven solution of an Alusil cylinder block but with a slightly different version of an iron coated piston that seems to be working well. They also do not have liners. It is more expensive to produce but results in a more reliable outcome.

Whether they will cover the same miles the 944/968's could (typically 250K)without bore problems remains to be seen but the only problem we have encountered so far is a very small number after many years and many hot/cold heat cycles have stress relieved in the bores and closed the clearances up - sometimes resulting in bore damage


Baz

:worship: :worship: I really enjoy reading your posts Baz its so informative :thumb: :thumb:

Mine is on its way to Hartech today so Baz can find out what the hell's going on with it and if its electrical or mechanical. :thumb: