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Big Bob
Barcelona


Joined: 23 Jan 2008
Posts: 1348
Location: Southampton


PostPosted: Thu Jun 25, 2009 8:16 pm    Post subject: Reply with quote

In reply to ZigZag, the Left Bank contains the exhaust to bore no 6.
The failure that a few of us are trying to pin down that has affected in excess of 40+ 997 Gen 1 Standard Engines, is caused by the erosion or destruction of the Nikasil coating on the no 6 bore in particular.
This results in increased oil consumption because of oil blow by as the bore loses its geometry, and the piston Rings can't seal as well. This results in reduction in compression, and an increase in noise caused by "piston slap" in the effectively worn bore. In some cases because the piston rings start to run on the parent alluminium of the bore i.l.o. the Nikasil Coating, you can then get pick up betwwen the base bore cast alluminium and the piston, that results in partia seizure and piston ring breakage.
Personally ZigZag you need to have an endoscopic examination of the Bores associated with the Left Bank to identify if it is a bore erosion issue with the Nikasil Coatings.
If it is not then the check may identify other potential causes for grater oil use on the Left Bank.
I'm not trying to be alarmist but please get it checked to be on the safe side.
If this is the problem (ie Nikasil Lining Erosion), I trust you have an effective warranty as it will lead to either a full rebuild or a new/replacement engine.
Commiserations if I'm right Sad . And I sincerely hope I am not nooo .
Best Regards Big Bob bye
 
  
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Porkaholic
Spa-Francorchamps


Joined: 11 Jan 2009
Posts: 323
Location: Cornwall

2009 Porsche 997 Carrera 4S

PostPosted: Thu Jun 25, 2009 9:33 pm    Post subject: Reply with quote

Is this a silly question?
Question How about putting some of that Slick50 product with PTFE lining properties? Would that help or is it just another marketing myth?
 
  
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theogeor
Albert Park


Joined: 22 Sep 2008
Posts: 1502
Location: Northwood Hills

2006 Porsche 997 Carrera 2

PostPosted: Thu Jun 25, 2009 10:32 pm    Post subject: Reply with quote

Porkaholic wrote:
Is this a silly question?
Question How about putting some of that Slick50 product with PTFE lining properties? Would that help or is it just another marketing myth?


To be honest I think is waste of money if you have a Nikasil issue. As Big Bob said the cause of the problem is unknown and might be related to fuel contamination or some other factors. If the problem starts then is too late...
_________________
911 997 C2 56 Reg
B180 SE 14 Reg (family car)
406 Coupe (Now in Cyprus as a holiday car)
A160 Blueefficiency Avantgarde 11 Reg (second holiday car in Cyrpus)
 
  
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Pete Hadfield
Suzuka


Joined: 06 Sep 2008
Posts: 1147
Location: 25 miles north of Manchester

2007 Porsche 997 Carrera 2S

PostPosted: Fri Jun 26, 2009 6:31 am    Post subject: Reply with quote

It's not always doom and gloom thumbsup

Only sometimes wack
_________________
Pete,

997 C2S, no longer a 'Ring virgin
 
  
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jldbeemer
Newbie


Joined: 24 Jun 2009
Posts: 18
Location: cheshire


PostPosted: Tue Jul 07, 2009 11:08 am    Post subject: Reply with quote

Hi all,
i have a 54 plate c2s tip with only 25k miles, its running perfectly with no issues at all, i have noticed the n/s tailpipes do get dirtier than the o/s though?!
Do i have a reason to worry? after reading this topic i have heard it mentioned. Confused
 
  
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bazhart
Approved Trader


Joined: 20 May 2009
Posts: 1038
Location: Bolton Lancashire


PostPosted: Tue Jul 07, 2009 1:39 pm    Post subject: Reply with quote

Although I have a lot of experience of Nikasil (going back perhaps 37 years or so) and a lot of experience of the problems, causes and solutions to 996 engine failures (which might be useful in exploring the possibile reasons for these failures) - I have not yet had to see inside a 997 engine - but I thought that the early 997's had Lokasil cast in liners and only the new generation engines 2009 onwards had Nikasil bores.

Perhaps someone could clarify this before I make any suggestions or observations that might prove misleading.

Baz
 
  
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Big Bob
Barcelona


Joined: 23 Jan 2008
Posts: 1348
Location: Southampton


PostPosted: Tue Jul 07, 2009 3:01 pm    Post subject: Reply with quote

Very intersting bit of info Baz. I'll delve further. Regards Big Bob bye
 
  
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bazhart
Approved Trader


Joined: 20 May 2009
Posts: 1038
Location: Bolton Lancashire


PostPosted: Tue Jul 07, 2009 3:57 pm    Post subject: Reply with quote

I'll wait with interest Bob - but will not be able to respond for a couple of weeks - so you have plenty of time.

If they do have the same Lokasil cast in liners as earlier engines I can explain possible causes and if they have Nikasil bores I can suggest some potential reasons. However I don't want to mislead anyone and having not been inside one of the early 997 engines yet - cannot be sure - although from everything I read and see they seem like the same engine as later 996 ones.

Till late July then - Baz - and thanks for trying to check it out.
 
  
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bazhart
Approved Trader


Joined: 20 May 2009
Posts: 1038
Location: Bolton Lancashire


PostPosted: Wed Jul 08, 2009 7:16 am    Post subject: Reply with quote

Sorry Bob - got myself confused there as I was rushing to answer - just to correct I thought the latest new generation 2009 engines were Alusil as used in the 944 and 968 (not Nikasil).

As far as I am aware Nikasil was used in all later air cooled engines and Lokasil in all Boxsters and 996 standard cars.

996 Turbos and GT models with seperate 3 cylinder blocks were Nikasil (I believe).

The relevant question mark is over the 997 standard models which I assumed were still using Lokasil blocks (for which the reasons for seizures are relativley easy to explain and list).

Hope my error didn't waste any of your time and looking forward to your results.

Baz
 
  
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Big Bob
Barcelona


Joined: 23 Jan 2008
Posts: 1348
Location: Southampton


PostPosted: Wed Jul 08, 2009 7:56 am    Post subject: Reply with quote

Baz no problem, however based on the attached report:
http://www.rheinmetall.de/index.php?lang=3&fid=1504

Lokasil was the material used from February 2005 for 997 Engines (Except Turbo and GT3 ie Nikasil).
So you may still have a contribution here based on your knowledge of Lokasil in 996 and Boxster production.
Best Regards Big Bob bye
 
  
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bazhart
Approved Trader


Joined: 20 May 2009
Posts: 1038
Location: Bolton Lancashire


PostPosted: Wed Jul 08, 2009 8:53 am    Post subject: Reply with quote

I agree Bob - I think the Turbo and GT engines had Nikasil wet liners, but the 996 and 997 had Lokasil.

I have reported in great depth on other web sites about Lokasil and a lot on our own web site www.hartech.org buyers guide.

I wrote my thesis in that guide on what was causing the cracks and seizures many months ago but it all seems quite right now.

Lokasil is a metal matrix composite and as such not very strong and prone to creep. Even new blocks I have measured have crept slightly oval and this continues in the thrust direction until the bore can be 10 or 12 thou oval (0.25mm to 0.3mm) after which they usually crack.

The smaller Boxster blocks have thicker wall thickness outside the Lokasil cast in liner and so are stronger.

The 996 was bored out from the Boxster S casting reducing the wall thickness by half the bore diameter difference (1.5mm) despite producing more torque.

When they distort the 90 degree direction gets smaller in diameter as the thrust direction diameter gets bigger (i.e. it is not wear). Piston rings cannot fit into such an oval bore if they have not worn with it (and they don't) so eventually there is too much blow by and this overheats the oil on the thrust face and causes a seizure.

Also the sealant used on the crankcase halves leaves a smear inside the oil galleries to the crankshaft which eventually falls of and can block the oil spray jets that send oil up into the cylinder and piston area. This can also cause seizures.

I wonder if the later engines with variable lift and greater torque result in more blow by (as torque is somewhat proportional to cylinder pressure) than earlier engines? or the extra torque results in even faster distortion rates? I have not yet seen an "S" engine with 3.8 litres which has a piston 3 mm bigger still in diameter but wonder if they increased the wall thickness for that one - time will tell.

When we rebuild these engines we replace the cracked bores with a new cylinder liner with Nikasil lining and the other bores that have gone oval (the ones that have not cracked) we reduce the ovality and support with a ring so no further distortion is possible and the resulting engines are much sharper, crisper and faster as a result of correcting the poor cylinder filling and increasing the effective compression pressure (i.e. torque).

Unfortunately over sized pistons are not available and unless they have a special ptfe type coating - aluminium pistons apparently don't run well in Lokasil - otherwise they could be bored out as there is plenty of wall thickness and support rings would prevent future distortion (something that should have been fitted to the original engines in my view).

No more time for now!

Baz
 
  
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Big Bob
Barcelona


Joined: 23 Jan 2008
Posts: 1348
Location: Southampton


PostPosted: Wed Jul 08, 2009 9:24 am    Post subject: Reply with quote

Thanks Baz worship
That is most illuminating, and certainly explains why as part of the failure mode, initially the owner notices an increase in oil blow by in the exhaust system, and then loss of compression.
In your 8th para you talk about sealant that can impact oil spray and supply to the piston bores.
Is there any likelihood that to resolve other known oil leak issues on the engine, that sealant is more likely to impact the rear no 6 bore, which seems to be a more regular factor in the 40+ failuresa that we are vaguely aware about?

Best Regards and thanks for your time Thumb
Big Bob bye
 
  
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bazhart
Approved Trader


Joined: 20 May 2009
Posts: 1038
Location: Bolton Lancashire


PostPosted: Wed Jul 08, 2009 10:08 am    Post subject: Reply with quote

Bob, hoping to look into a 997 engine shortly and will let you know if they changed anything.

The no 6 main bearing is the most likely to wear prematurely (as the overhang at the rear of the crankshaft is large and the cranks flex at this end) and when it does the swarf also blocks the oil spray jet on that cylinder - so are the mains failing prematurely as well? - something I don't know the answer to yet because like the early 996 problems - most have been resolved under warranty at the main agent up to now. Only expect to see them here shortly from which more explanations will no doubt follow.

Thats it now for two weeks or so. At least - if I am right about the Lokasil liners - some of the misleading comments about Nikasil ***** off etc - can be ignored for clarity.

Baz
 
  
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c.afsar
Hockenheim


Joined: 08 Jul 2007
Posts: 724
Location: London

2003 Porsche 996 Carrera 4

PostPosted: Wed Jul 08, 2009 1:18 pm    Post subject: Reply with quote

Very interesting read... Will wait for your findings Baz... Thumb
 
  
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bazhart
Approved Trader


Joined: 20 May 2009
Posts: 1038
Location: Bolton Lancashire


PostPosted: Thu Jul 23, 2009 12:50 pm    Post subject: Reply with quote

Back from hols now and wondering if in my absence anyone has found anything new out or anything of interest to resurect this subject?

Baz
 
  
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Big Bob
Barcelona


Joined: 23 Jan 2008
Posts: 1348
Location: Southampton


PostPosted: Thu Jul 23, 2009 3:04 pm    Post subject: Reply with quote

Not at present Baz, but I have been speaking to someone who knows you up in Fife, and used to have you look after his 968 some time ago, and is concerned he has a similar issue apparent on his 2007 Cayman.
Send me a PM and I'll re connect the individual. He has read this entire Post and feels that Edingurgh OPC are worried etc.
Regards Big Bob
 
  
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