Borescore - How do you know ?

Milo72 · 29 Sep 2018

Other than a camera to have a look inside how do you know if you have bore score ?

I've read that black near side exhaust tips.... anything else ?what about burning oil or oil spray out the back? I've also read about ticking, but if you are paranoid you can hear ticking on even the tightest engine.

Any clues ?

Phil 997 · 29 Sep 2018

The only real way to know mate is a borescope. yes some say ticking but these engine tick anyway , sme say burning a lot of oil but even Porsche say up to 1ltr per 1000 miles is within spec , sooty left tail yes but also other things can cause sooty tailpipes.

also even if you get a scope unless the guy is very experienced with this issue he maywell missdiagnose normal bore scuff as the dreaded scoring . So basically choose someone with a very good rep and get a scope,

or stop being paranoid, assume you are one of the 95% and not one of the 5% and enjoy the car :grin: :grin: :thumb:

deMort · 29 Sep 2018

The only proper way is to remove the cyl head and have a look !!

Borescope .. its a small picture , if your not used to it then any scratch seems large .

A black tail pipe on one side is an indication , an eml or running faults listing misfires is another .

A knocking noise is pretty much only in extreme cases .. when the wear is so bad the piston slaps side to side .

Unfortunatly the only cheap way is a scope check but you are left with the mechanics ability to diagnose accurately from this.

Milo72 · 29 Sep 2018

Thanks for the advice - I have it booked it at RPM in a few weeks for a service and a borescope... just wondered if I could pre-empt it.

Googling the Gen 1 engine and it's problems is like googling when you have indigestion and giving yourself 10 mins to live because of heart failure.

Phil 997 · 30 Sep 2018

Milo72 said:
Thanks for the advice - I have it booked it at RPM in a few weeks for a service and a borescope... just wondered if I could pre-empt it.

Googling the Gen 1 engine and it's problems is like googling when you have indigestion and giving yourself 10 mins to live because of heart failure.

:grin: :grin: Remember no one goes on the internet and says "guess what I drove my 997.1 all day today and nothing happened " or " I havent got sooty tailpipes or any high oil usage so I am just posting this to let everyone know I am not worried about my car " :floor: so all you ever see are the moans and groans of the 5% that have had this issue, as the other 95% are at home chilling out and happy. I think its a good idea to get it scoped by a good indy as you then know where you stand and assuming its all good and your in the 95% club then you can follow the reccomended ways to minimise risks , which I am sure your aware of but if not let me know and I will list or go on Hartechs web site and read what to do. :thumb: :thumb:

resigner · 30 Sep 2018

You didn't say why you asked?

Do you already own the car?

Has it got sooty pipes on one side?

Mine recently had sooty tail pipes, on both sides. It need a new oil seperator, nothing more, and yes it had noticeably started using a lot of oil!!!

It's all good now though

Get the pictures from RPM when you have it done and put them up. Demort usually doesn't mind having a look.

Milo72 · 30 Sep 2018

resigner said:
You didn't say why you asked?

Do you already own the car?

Has it got sooty pipes on one side?

Mine recently had sooty tail pipes, on both sides. It need a new oil seperator, nothing more, and yes it had noticeably started using a lot of oil!!!

It's all good now though

Get the pictures from RPM when you have it done and put them up. Demort usually doesn't mind having a look.

Yes have the car... I knew about about Borescore and the IMS bearing issues on these cars before I bought it, but I didn't get any internal engine inspection on it which I slightly regret now.

It's not showing any signs of any problems, had a full OPC service history and looks like it's been really loved.

I booked it in for a service and they wanted to do a borescope first before anything else, wasn't sure if they wanted to take a few more £'s or there are genuinely real problems and more than the 5% commonly mentioned.

Magic919 · 30 Sep 2018

It's a genuine problem, but clearly not all cars currently suffer. The 5% is just an invented number, so I wouldn't pay it too much heed.

Phil 997 · 30 Sep 2018

yes agreed 5% is just the accepted best guess from marque specialists. it could very easily be 4% :floor: :floor:
but as there are no records there really is no way of knowing the actual number and in all seriousness it could be anything from 2% to 10% but its still relatively low compared to cars that are not suffering from scoring. :thumb:

michaelbbwalker · 30 Sep 2018

has anyone actually worked it out, it's published how many 3.8 997.1s were made, I'm sure if someone who had a lot of free time searched this and other forums for who has had a rebuild or replacement engine you could hazard a guess... I know not everyone goes online but wondered if anyone has taken a proper stab at it?

Frenchmeister · 30 Sep 2018

I have had my 3.8 for 4 years now, low temp stat, 5/40 w oil, additional centre radiator which is as cheap as chips from main dealer, kept under 3k until oil temp is up and never laboured from low rpm when wanting to move on.
So far so good, if it blows up I will get it future proofed and have an epic iconic sports car in fine fettle for just over 30k which will not buy you a sporty golf !
Doh !
:thumbs:

deMort · 30 Sep 2018

It used to be the official line from porsche .. if there was more than 5% of a problem world wide then it was an issue subject to a campaign or a recall .

less than and it was deemed acceptable and delt with under warrenty .. if you dont take the extended warrenty then it was your choice not to do so and you pay .

Fair or not is something i cant comment on .. that used to be the the rules when i last worked there .

Norfolk &amp; Idea · 1 Oct 2018

I read an article in 911 & Porsche World (I think it was that mag?) that a possible of cause of the problem with 997.2 bore scoring was the injector stem seal... It sounded a plausible theory when I read it.

bazhart · 1 Oct 2018

With Lokasil or Alusil engines - bore scoring is usually caused when small particles of silicon become detached from the cylinder bore base aluminium and can float in between the cylinder bore and the piston, suspended in the oil and squashed between the piston and the cylinder bore when the engine is under load and the piston is transferring the force on the con road that pushes it against the cylinder wall into rotary force at the other end of the con-rod via the crankshaft.

The thinner the oil (and/or hotter it is) and the greater the force (throttle opening) the more likely the small piece of silicon is to damage the surfaces. The more worn away the piston coating is - the more likely it is to impinge on the aluminium, get stuck there and run up and down the cylinder - often causing more particles to release.

The older the engine the more wear the piston coating has had and the nearer it will be to particles damaging it more quickly.

Alusil has good even dispersion of particles because the come out of the Molten aluminium during casting and form/grow evenly and very well retained in the base material. But the aluminium still wears away slowly and eventually as age and mileage increase, particles become loose more often.

Lokasil does not have such an even distribution and larger silicon particles and with age they become loose more often.

Ferrous coated pistons (early cars) can resist the small particles and allow them to roll/flush away with the oil for a long time.

Plastic coatings do not last as long because they are softer (especially at elevated temperatures) and can even become de-bonded from the piston face whereas ferrous coatings are plated onto the piston and last longer.

With Alusil and some form of electro-plated piston coating - as long as the clearance between the piston and the cylinder wall is right - they can usually last for massive mileages.

With Lokasil there is a variation in the larger particles of silicon distribution and bonded strength that results in a variable rate of release resulting in a shorter expected lifespan and plastic coated pistons deteriorate over time.

Furthermore crankshaft bearings wear and could usually benefit from replacement by 70 to 100K.

So if you have a Lokasil engine with plastic coated pistons and the coating is not 100% perfect, the distribution of silicon is poor, thin oils are used with engines running hot, aggressive driving on full throttle as often as possible etc there is every likelihood that the engine will require rebuild by 100K or less.

If on the other hand you have a well bonded set of plastic coated pistons, a good distribution of well bonded silicon particles, a thicker oil (as the engine ages), a careful driver among all the owners that never thrashed the car etc etc - you may well get away with huge mileages before rebuild is required.

It is this variation in the original car's engine, driver style and oils etc that creates an almost impossible problem in predicting reliability rates - however - one thing is sure - the older the car and the more owners it has had - the greater the chances of it falling into one of the less reliable categories described above.

They are brilliant cars priced accordingly to reflect the unreliability concerns of prospective owners and since repairs like ours are reliable and use Nikasil bores (that have no known weak areas and can run with or without any piston coatings reliably) it is possible to improve the base reliability.

If a rebuild is necessary then for a small extra cost we can upgrade performance with our oversized engine rebuild options.

Baz

Norfolk &amp; Idea · 1 Oct 2018

bazhart said:
With Lokasil or Alusil engines - bore scoring is usually caused when small particles of silicon become detached from the cylinder bore base aluminium and can float in between the cylinder bore and the piston, suspended in the oil and squashed between the piston and the cylinder bore when the engine is under load and the piston is transferring the force on the con road that pushes it against the cylinder wall into rotary force at the other end of the con-rod via the crankshaft.

The thinner the oil (and/or hotter it is) and the greater the force (throttle opening) the more likely the small piece of silicon is to damage the surfaces. The more worn away the piston coating is - the more likely it is to impinge on the aluminium, get stuck there and run up and down the cylinder - often causing more particles to release.

The older the engine the more wear the piston coating has had and the nearer it will be to particles damaging it more quickly.

Alusil has good even dispersion of particles because the come out of the Molten aluminium during casting and form/grow evenly and very well retained in the base material. But the aluminium still wears away slowly and eventually as age and mileage increase, particles become loose more often.

Lokasil does not have such an even distribution and larger silicon particles and with age they become loose more often.

Ferrous coated pistons (early cars) can resist the small particles and allow them to roll/flush away with the oil for a long time.

Plastic coatings do not last as long because they are softer (especially at elevated temperatures) and can even become de-bonded from the piston face whereas ferrous coatings are plated onto the piston and last longer.

With Alusil and some form of electro-plated piston coating - as long as the clearance between the piston and the cylinder wall is right - they can usually last for massive mileages.

With Lokasil there is a variation in the larger particles of silicon distribution and bonded strength that results in a variable rate of release resulting in a shorter expected lifespan and plastic coated pistons deteriorate over time.

Furthermore crankshaft bearings wear and could usually benefit from replacement by 70 to 100K.

So if you have a Lokasil engine with plastic coated pistons and the coating is not 100% perfect, the distribution of silicon is poor, thin oils are used with engines running hot, aggressive driving on full throttle as often as possible etc there is every likelihood that the engine will require rebuild by 100K or less.

If on the other hand you have a well bonded set of plastic coated pistons, a good distribution of well bonded silicon particles, a thicker oil (as the engine ages), a careful driver among all the owners that never thrashed the car etc etc - you may well get away with huge mileages before rebuild is required.

It is this variation in the original car's engine, driver style and oils etc that creates an almost impossible problem in predicting reliability rates - however - one thing is sure - the older the car and the more owners it has had - the greater the chances of it falling into one of the less reliable categories described above.

They are brilliant cars priced accordingly to reflect the unreliability concerns of prospective owners and since repairs like ours are reliable and use Nikasil bores (that have no known weak areas and can run with or without any piston coatings reliably) it is possible to improve the base reliability.

If a rebuild is necessary then for a small extra cost we can upgrade performance with our oversized engine rebuild options.

Baz

Interesting, and thanks for the informative post. So, in your expert opinion- is the injector stem seal theory a load of bollox? Or is it possible the injectors could be a contributing factor?

And I guess the short and tall of it is, is if you run a high power engine, a rebuild is inevitable eventually. Nothing new there. I've had a few bike engines rebuilt after considerable track work.

Borescore - How do you know ?

Milo72

Spa-Francorchamps

Phil 997

Le Mans

deMort

Monaco

Milo72

Spa-Francorchamps

Phil 997

Le Mans

resigner

Barcelona

Milo72

Spa-Francorchamps

Magic919

Mugello

Phil 997

Le Mans

michaelbbwalker

Trainee

Frenchmeister

Barcelona

deMort

Monaco

Norfolk & Idea

Mugello

bazhart

Barcelona

Norfolk & Idea

Mugello

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