Has your 996 or 997 engine had a major rebuild?

Has your 996 or 997 engine had a major rebuild?

Poll: Has your 996 or 997 engine had a major rebuild?

Total Members Polled: 867

No: 488
Yes because of the IMS: 65
Yes because of scored bores: 91
Haven't bought one because of known faults: 183
Yes because of D Chunk failure: 9
Re-built prior to purchase, not sure why?: 44
Author
Discussion

PP 997

25 posts

108 months

Wednesday 22nd July 2015
quotequote all
Well in Feb this year I purchased a one owner 2005 S with 33,000 miles

Took it over to Revolution at Brighouse last week

We arrived at 8 am and it was nice to see 5 Porsche there on ramps

Cut to the chase

Borescope result clean - Russ phoned me at 11am

Then two front shocks / 4 new Bridgestone/ New disc at front / low temp therm etc / black mesh grill / Waxoyle underneath / brake fluid change etc

They also booked us in to a really nice hotel four minutes walk away

The bore score issue was doing my head in to be honest / Russ explained Doris ! had a single scuff on each wall on 4 5 and 6 / they also took the time to bore scope 1 2 and 3 with the same outcome

I just felt relieved

When we drove home for the first time in 6 months my 997 felt right








Terminator X

14,921 posts

203 months

Wednesday 22nd July 2015
quotequote all
Currently at a 25% failure rate, only on P/Heads rofl

TX.

Magic919

14,126 posts

200 months

Wednesday 22nd July 2015
quotequote all
25% of mine have failed.

mollytherocker

14,365 posts

208 months

Wednesday 22nd July 2015
quotequote all
Terminator X said:
Currently at a 25% failure rate, only on P/Heads rofl

TX.
Whats the real current % failure rate?

hartech

1,929 posts

216 months

Thursday 23rd July 2015
quotequote all
Let me try and be brief about explaining bore scoring.

ALUSIL crankcases (924S, 944 & 968) were aluminium with silicon (small hard particles) mixed in at a higher proportion than could be absorbed in a solution - so some formed hard nodules that were very evenly distributed and securely stuck within the matrix creating a hard bore surface. But the silicon was throughout the casting making it expensive to machine but very strong and stable - usually lasting well over 250K.

The pistons had a hard thin ferrous coating that resisted wear from the silicon particles standing slightly proud in the in the cylinder bore surface - very well.

If they ever failed it was almost always the rear cylinder 3 or 4 that went first (usually because the head gasket had rotted and short circuited the coolant so cylinders 3 & 4 ran hotter) because the higher temperatures made the oil film between the piston and bore thinner allowing the piston to impinge on the bore harder and any lose silicon particles that became detached from the bore to rub harder against the ferrous coating and eventually wear through it (and this has been tested and proven over many years with a magnet in scored piston areas).

LOKASIL was described as being much the same as Alusil but was actually quite different having slightly larger silicon particles held in a porous - pre-formed cylinder tube with molten aluminium forced through the porosity during high pressure casting in metal tools - to entrap the silicon as it solidified.

The resulting crankcase only has silicon near the cylinder bore (so was cheaper to manufacture) but the cylinder tube was weaker than Alusil (and gradually distorted oval) while the silicon particles were not only bigger but also less secure and became detached at a higher rate or lower mileage.

The cylinder block used in Alusil has 100% of the coolant passing into it before the cylinder heads (helping the oil film to stay thiker) whereas the M96 and M97 engines had only around 10 to 12% of the coolant passing into the cylinder block - and so in some situations could allow the cylinder block to run hotter and the oil viscosity (and the resulting film thickness) to be thinner.

The first Lokasil engines (Boxster2.5 up to most 3.4 996's) also had the same hard ferrous coated pistons (previously used in Alusil made by the same manufacturers of the Lokasil crankcases) that despite the potentially higher cylinder temperatures resisted the higher silicon degradation rates better.

Towards the last 3.4 996's the piston supplier and specification was changed to softer plastic coated pistons (similar to the aftermarket ones that were generally not quite as long lasting as the original ferrous coated ones in the better cooled Alusil examples).

The combination of less coolant volume/flow, bigger more powerful engines (that followed), probably larger silicon particle sizes (in Lokasil 2) and plastic coated pistons reduced the lifespan further and added scored bored to the probability of eventual distortion cracks later on.

It also seems likely that the distribution of silicon in Lokasil is not as even as the silicon undisolved in Alusil and not as strongly secured - while the tube created in Lokasil is less strong than the same sized tube in Alusil - migrating oval in the thrust direction, increasing piston blow by and surface temperatures, reducing oil film viscosity and cracking or "D" chunking.

Cars driven less aggressively (with lower torque at lower revs) will run cooler at the piston surface and keep the oil film thicker and apply less load to disturb the silicon particles - so will last longer although the variation in silicon distribution in Lokasil - may add a random risk to reduce failure predictability.

It all means that even if a car has not suffered bore scoring yet - it could still do so in the future (sooner than that expected with "older" models) - although some could well last a long time if the material composition in all 6 Lokasil cylinder tubes in that engine was above average, the driving styles applied were suitable and some additional preventative measures were applied (like a LTT and avoiding high torque at lower revs particularly after a pause that creates heat soak).

Gen 2 engines corrected many of those Gen 1 problems by reverting to Alusil, closing the deck (to stop distortion) and running more coolant through the cylinder - but the pistons still have the less durable plastic coating and so although they may last longer than Gen 1 cylinders - they would be unlikely to last as long as the original Alusil engines with ferrous coated pistons.

Meanwhile the engines made with Alloy Nikasil bores (all air cooled engines for decades and water cooled GT3 and Turbo engines) have closed deck (and/or supported cylinders), more coolant (or air) flow and no bore/piston problems (and could run with almost any piston coating as there is no silicon particle degradation with Nikasil and a naturally oil retaining surface) - all just the same as our own Nikasil alloy cylinder replacements.

Meanwhile - while we are not trying to scare any Gen 2 owners - we suspect that while they should last longer than Gen 1 cylinders - they may not last as long as the original Alusil engines with ferrous coated pistons. In the same way that we backed our expectations for Lokasil and developed and tested a cylinder solution early on (that provided us with a market lead) - we now seek a Gen 2 car with a cylinder bore problem to start developing a solution just in case they start to fail as well.

If we are proven wrong - we will have harmed no one and wasted some of our own money on an unnecessary project - if not we will have reproduced the scenario that enabled us to lead the market for IMS problems, cylinder cracks and "D" chunking, a valved racing sump extension that actually worked, the Low Temperature Thermostat, the third radiator control thermostat housing etc. We are less sure that this is necessary than we were with previous problems and if it turns out our suspicions are wrong on this occasion - will actually be pleased for the owners of the cars we make our living from looking after - who then don't have to suffer as many have in the past - but following our early analysis as early as possible proved worthwhile in the past and all business is a risk in some way or another!

Baz



Chris Stott

13,186 posts

196 months

Sunday 23rd August 2015
quotequote all
AOS went on my mk1 996 last week.

Had the car recovered to my Indy, and whilst replacing the AOS they had a look at the bores. They said other than a couple of very small marks it was in fine condition.

153k miles.

bigkeeko

1,370 posts

142 months

Sunday 23rd August 2015
quotequote all
I kinda touched on this on another thread and felt it wasn`t appropriate but it may well be here.

Not mine but, living in a small town with only 3 Porsches that I`ve known about (not including my arrival next week).
There was a 1998 (I`m sure it was) 3.4 996. A 2011 Cayman R and a 2006 C2S. Out of the three one had major engine surgery after a year of ownership having not been too `healthy` for a while. It was the 2006 C2S and from what I remember it was immaculate and well looked after.
Obviously (FAO doom mongerers here) that doesn`t equate to 1 in 3 cars needing rebuilt because if it was the only Porsche here then according to some that would be a 100% failure.

hartech

1,929 posts

216 months

Monday 24th August 2015
quotequote all
Statistics are always a problem area - always easy to criticise as well.

Firstly the older 3.4 996's (apart from the very last built) had ferrous coated pistons and almost never score bores - their problems are mainly cracked or "D" chunked cylinders and IMS failures.

Secondly failures would be covered in the first years of ownership by the manufacturers warranty and the large number in the first few years who can afford to extend the Porsche warranty while the car is still expensive. Many others do not report failures (embarrassed that they bought "a pup" although the failure would probably not be their fault) - but you often find friends and acquaintances are only too ready to put the spoke in when you have a problem with your lovely car.

Most fault become a problem between about 4 and 8 years of ownership (when most have no warranty anymore) and by then they often have had 3 or 4 owners. Once properly repaired they should b good for many years afterwards.

I am not sure where the 1 on 3 statistic came from but the cylinders going oval will be progressive and so will the wear on the plastic coated pistons etc - so how long they last will be a function of how all the various owners drove them, ambient conditions, care, oil used and we think probably a random Lokasil quality factor.

IF say the various failure incidences recorded were 20% over say 8 years from new then that would probably only be one of the 4 owners - so actually statistically be 5% of owners experiencing a failure by that age. Factor in the numbers not recorded and repaired or replaced under Porsche warranty and the numbers increase once again.

What cannot be disputed is that very much greater number than Porsche engines ever experienced before - do fail and replacement new engines embody the same technology while some rebuilders modify particular areas and reduce the chance of further failures - improving the outcome (and usually for a significantly lower cost).

Similarly it cannot be disputed that most buyers spend most of their available "car cash" on the best examples they can afford and so often have little available to rebuild a complete engine if a failure occurs - and the older and cheaper the car the less likely they are on average to be able to afford to repair it.

Information trying to establish the likelihood of a failure can be valuable to such buyers in trying to work out what they should buy, how much to spend and what to keep in reserve or put into a reliable warranty of some kind or another.

Great cars - small chances of failures - repair options available (some better than others) and a pleasure to own but sensible to assess the possibilities and understand the risk rather than buy blind and experience a potential financial disaster.

Baz

hartech

1,929 posts

216 months

Monday 24th August 2015
quotequote all
For more information - they say a picture is worth a thousand words - so you might be able to understand more by looking at our video available from our web site www.hartech.org.

It is 10 minutes long (which is thought to be too long by video experts who think 2 minutes is the maximum) but we cut it as small as we could. We also had to shoot over 200 shots in 2 days and unfortunately to set all that up for the 100 or so actually used meant a few difficulties getting the right parts in the right place etc (like using parts that had not yet been fully cleaned etc), but we hope it is received as useful and helpful.

When I was involved in the Silver Dream Racer film it was 8 weeks for 90 minutes (and that was with experts and weeks to prepare) so believe me - for us to get all that in within 2 days was really complicated and difficult.

Any feedback would be useful (perhaps on a new posting about it?)

Hope it proves to add to the information we try to provide for owners to understand the problems and solutions available when they have engine problems.

Baz


HoHoHo

Original Poster:

14,980 posts

249 months

Monday 24th August 2015
quotequote all
hartech said:
For more information - they say a picture is worth a thousand words - so you might be able to understand more by looking at our video available from our web site www.hartech.org.

It is 10 minutes long (which is thought to be too long by video experts who think 2 minutes is the maximum) but we cut it as small as we could. We also had to shoot over 200 shots in 2 days and unfortunately to set all that up for the 100 or so actually used meant a few difficulties getting the right parts in the right place etc (like using parts that had not yet been fully cleaned etc), but we hope it is received as useful and helpful.

When I was involved in the Silver Dream Racer film it was 8 weeks for 90 minutes (and that was with experts and weeks to prepare) so believe me - for us to get all that in within 2 days was really complicated and difficult.

Any feedback would be useful (perhaps on a new posting about it?)

Hope it proves to add to the information we try to provide for owners to understand the problems and solutions available when they have engine problems.

Baz
Appreciate this is not a new thread Baz - however a very good video and very informative. Only comment is I couldn't read the ticker and watch the video at the same time!

Richie200

2,011 posts

208 months

Monday 24th August 2015
quotequote all
hartech said:
For more information - they say a picture is worth a thousand words - so you might be able to understand more by looking at our video available from our web site www.hartech.org.

It is 10 minutes long (which is thought to be too long by video experts who think 2 minutes is the maximum) but we cut it as small as we could. We also had to shoot over 200 shots in 2 days and unfortunately to set all that up for the 100 or so actually used meant a few difficulties getting the right parts in the right place etc (like using parts that had not yet been fully cleaned etc), but we hope it is received as useful and helpful.

When I was involved in the Silver Dream Racer film it was 8 weeks for 90 minutes (and that was with experts and weeks to prepare) so believe me - for us to get all that in within 2 days was really complicated and difficult.

Any feedback would be useful (perhaps on a new posting about it?)

Hope it proves to add to the information we try to provide for owners to understand the problems and solutions available when they have engine problems.

Baz
Hi Baz, I couldn't find the video on your site???

318touring

25 posts

151 months

Monday 24th August 2015
quotequote all

Richie200

2,011 posts

208 months

Monday 24th August 2015
quotequote all
Many thanks wink

BILLY 911

131 posts

145 months

Thursday 22nd October 2015
quotequote all
2005 997 Carrera S Tiptronic 65,000 Miles
Engine rebuild 59,000 Scored bores 2,4 & 6
Question :
Why do the Tiptronics seem more prone ?
Looking at the current crop of Carrera S Mk 1's on the Auto Trader 5 out of the 6 cars with advitised Engine rebuilds are Tips

mollytherocker

14,365 posts

208 months

Thursday 22nd October 2015
quotequote all
BILLY 911 said:
2005 997 Carrera S Tiptronic 65,000 Miles
Engine rebuild 59,000 Scored bores 2,4 & 6
Question :
Why do the Tiptronics seem more prone ?
Looking at the current crop of Carrera S Mk 1's on the Auto Trader 5 out of the 6 cars with advitised Engine rebuilds are Tips
I believe it is because they normally set off in second gear. The recommendation is too choose 1st 'manually'.

m444ttb

3,160 posts

228 months

Thursday 22nd October 2015
quotequote all
My 996 is off to Hartech on Saturday for the full works (in all probability) to draw a line under the excessive oil consumption and stop me having sleepless nights about bore score and IMS bearing failures. Hopefully it'll be a keeper after that.

LordHaveMurci

12,034 posts

168 months

Thursday 22nd October 2015
quotequote all
BILLY 911 said:
2005 997 Carrera S Tiptronic 65,000 Miles
Engine rebuild 59,000 Scored bores 2,4 & 6
Question :
Why do the Tiptronics seem more prone ?
Looking at the current crop of Carrera S Mk 1's on the Auto Trader 5 out of the 6 cars with advitised Engine rebuilds are Tips
Pretty sure if you read back through this thread, Baz from Hartech has written a detailed explanation, molly has summarised it quite well though from what I understand.

fastgerman

1,911 posts

194 months

Tuesday 3rd November 2015
quotequote all
Has anyone had a full rebuild (by anyone) and had another failure? if so, what was the cause?

m444ttb

3,160 posts

228 months

Tuesday 3rd November 2015
quotequote all
fastgerman said:
Has anyone had a full rebuild (by anyone) and had another failure? if so, what was the cause?
I havent seen anyone on here personally having had it happen, but Hartech definitely have engines that have been rebuild elsewhere with steel liners that come in needing another rebuild. I think liners spinner and/or dropping, or just not fitting properly in the first place is often the cause.

Tap450

44 posts

102 months

Sunday 15th November 2015
quotequote all
I was talking to a chap the otherday he has a 996 it's probably the cleanest on the road. He's been working with Evans waterless coolant apparently the bores score because of heat spots. Apparently Evans waterless coolant helps and with what they have tested so far they havnt had a car back that's had scored bores so many this is something to think about?