997.2 GT3 Engine score normal?
Discussion
Darranu said:
Run forest run.
Seriously the bores still have clear honing marks from new which backs up the mileage but evidence of scoring.
Not good, time to move to the next car.
Who requested the borescoping ? Or did the vendor provide them without asking ? Either way, avoid this one and find another.Seriously the bores still have clear honing marks from new which backs up the mileage but evidence of scoring.
Not good, time to move to the next car.
rare To see that - but a barrel and piston kit for a 3.8 is not a lot of money so a rebuilt is actually quite economical. Worrying to see that wear though. If it was caused by oil starvation, it’s likely that won’t be the only wear.
The dreaded inlet failure was not unknown on this engine. It’s why I opted for the 3.6 but if that issue has already been dealt with, the correct oil has been regularly changed and it hasn’t blown a water hose and run on a while, this is a very rare occurrence
The dreaded inlet failure was not unknown on this engine. It’s why I opted for the 3.6 but if that issue has already been dealt with, the correct oil has been regularly changed and it hasn’t blown a water hose and run on a while, this is a very rare occurrence
Steve Rance said:
rare To see that - but a barrel and piston kit for a 3.8 is not a lot of money so a rebuilt is actually quite economical. Worrying to see that wear though. If it was caused by oil starvation, it’s likely that won’t be the only wear.
The dreaded inlet failure was not unknown on this engine. It’s why I opted for the 3.6 but if that issue has already been dealt with, the correct oil has been regularly changed and it hasn’t blown a water hose and run on a while, this is a very rare occurrence
So Steve, what causes this to happen?The dreaded inlet failure was not unknown on this engine. It’s why I opted for the 3.6 but if that issue has already been dealt with, the correct oil has been regularly changed and it hasn’t blown a water hose and run on a while, this is a very rare occurrence
Don't be alarmed by these pictures they look like perfectly normal Nikasil bore polishing marks to me and of no consequence.
Unlike Lokasil or Alusil the GT3 models used the more expensive Nikasil plated alloy cylinders and despite the additional power of them and the similarly built Turbo's you never hear about cylinder problems because it is the very best surface finish available - it just costs more than the others - which a GT3 and Turbo price can accommodate.
In fact the construction is the same as our own replacement cylinders for Cayman S. 996 and 997 Gen 1 models that similarly do not score.
However the surface finish is so shiny and reflective that with modern boroscope cameras and lighting they can look as if they have scores - but it is only some polishing marks that have no depth and do not influence performance or long life.
Sometimes they are caused by the most minute change to the profile of the top edge of a piston ring (talking microns here) that just polish up one area more than another - still leaving far less wear, more round cylinders and better piston ring sealing than the original Lokasil cylinders did and better than the more improved Alusil.
This type of engine would have been a full race engine a few decades ago and rebuilt every few hundred miles and it is a great credit to modern production and Porsche that they can make something that performs so well last so long as they do - and the combination of this cylinder finish and long lasting piston rings helps achieve that but sometimes just results in a few lines in the bores that may make some miss-interpret as scoring - they are not - don't worry.
Of course other problems like poor oil quality, low levels, overheating, weak mixtures etc can make any piston expand and result in damage but when it does I have never seen it look like this so unless there is anything else to be concerned about - I think you are OK - your car is OK.
Happy days.
Baz
Unlike Lokasil or Alusil the GT3 models used the more expensive Nikasil plated alloy cylinders and despite the additional power of them and the similarly built Turbo's you never hear about cylinder problems because it is the very best surface finish available - it just costs more than the others - which a GT3 and Turbo price can accommodate.
In fact the construction is the same as our own replacement cylinders for Cayman S. 996 and 997 Gen 1 models that similarly do not score.
However the surface finish is so shiny and reflective that with modern boroscope cameras and lighting they can look as if they have scores - but it is only some polishing marks that have no depth and do not influence performance or long life.
Sometimes they are caused by the most minute change to the profile of the top edge of a piston ring (talking microns here) that just polish up one area more than another - still leaving far less wear, more round cylinders and better piston ring sealing than the original Lokasil cylinders did and better than the more improved Alusil.
This type of engine would have been a full race engine a few decades ago and rebuilt every few hundred miles and it is a great credit to modern production and Porsche that they can make something that performs so well last so long as they do - and the combination of this cylinder finish and long lasting piston rings helps achieve that but sometimes just results in a few lines in the bores that may make some miss-interpret as scoring - they are not - don't worry.
Of course other problems like poor oil quality, low levels, overheating, weak mixtures etc can make any piston expand and result in damage but when it does I have never seen it look like this so unless there is anything else to be concerned about - I think you are OK - your car is OK.
Happy days.
Baz
On Monday I will sort out some pictures of Lokasil and Alusil scoring from which you will very easily see the difference. Unfortunately I honestly cannot show you a Nikasil scoring because we have never had one.
From 40 years ago when we were racing with Nikasil plated alloy cylinders - if they seized up - you could usually see where the electro-plating was missing (remained stuck on the piston) leaving a patch with a few thousandths of an inch edge where the piston had stuck to the Nikasil and plucked it away from the cylinder wall. Mind you we didn't have means of taking pictures inside then - only inspecting them on strip down or with the head off.
Interpreting boroscope photos is a new experience and so rarely needed with Nikasil - it is not surprising if people get that wrong sometimes.
Nikasil is so good it is oleophilic (has an affinity with oil) and we have even had engines brought to us for repair from racing sources with various other failures where bits of metal have got into the upper cylinder and gone up and down the cylinder walls making little or no marks and easily honed true with hardly any change in size or clearance. It really is a superb material and the only downside is that it exhibits polishing marks that people understandably assume is scoring when there is nothing wrong with it and it is expensive and hence only on more expensive models or top quality repairs.
Baz.
From 40 years ago when we were racing with Nikasil plated alloy cylinders - if they seized up - you could usually see where the electro-plating was missing (remained stuck on the piston) leaving a patch with a few thousandths of an inch edge where the piston had stuck to the Nikasil and plucked it away from the cylinder wall. Mind you we didn't have means of taking pictures inside then - only inspecting them on strip down or with the head off.
Interpreting boroscope photos is a new experience and so rarely needed with Nikasil - it is not surprising if people get that wrong sometimes.
Nikasil is so good it is oleophilic (has an affinity with oil) and we have even had engines brought to us for repair from racing sources with various other failures where bits of metal have got into the upper cylinder and gone up and down the cylinder walls making little or no marks and easily honed true with hardly any change in size or clearance. It really is a superb material and the only downside is that it exhibits polishing marks that people understandably assume is scoring when there is nothing wrong with it and it is expensive and hence only on more expensive models or top quality repairs.
Baz.
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Slippydiff said:
Who requested the borescoping ? Or did the vendor provide them without asking ? Either way, avoid this one and find another.
I received the car and immediately upon starting her up my very first time, the CEL was on. I pulled the error code with a OBD2 scanner and got P0304 cylinder 4 misfire. Now keep in mind, the car was purchased from a high end dealer which they said was in perfect running condition. The car was running so rough I had it trailered to a Porsche dealer. They removed the plugs and saw the cylinders didn’t look healthy and took those photos for me. Told me I need to replace the engine... needless to say, this was a nightmare. Photos were shared from Porsche dealer to the dealer I purchased the car from. Selling dealer disagreed with Porsche dealer and suggested to replace new plugs and coils. Now I have the car and it’s running fine. However, I still have the opportunity to reverse the transaction. So here I am doing research on how ‘normal’ these marks are if at all.
hartech said:
Don't be alarmed by these pictures they look like perfectly normal Nikasil bore polishing marks to me and of no consequence.
Unlike Lokasil or Alusil the GT3 models used the more expensive Nikasil plated alloy cylinders and despite the additional power of them and the similarly built Turbo's you never hear about cylinder problems because it is the very best surface finish available - it just costs more than the others - which a GT3 and Turbo price can accommodate.
In fact the construction is the same as our own replacement cylinders for Cayman S. 996 and 997 Gen 1 models that similarly do not score.
However the surface finish is so shiny and reflective that with modern boroscope cameras and lighting they can look as if they have scores - but it is only some polishing marks that have no depth and do not influence performance or long life.
Sometimes they are caused by the most minute change to the profile of the top edge of a piston ring (talking microns here) that just polish up one area more than another - still leaving far less wear, more round cylinders and better piston ring sealing than the original Lokasil cylinders did and better than the more improved Alusil.
This type of engine would have been a full race engine a few decades ago and rebuilt every few hundred miles and it is a great credit to modern production and Porsche that they can make something that performs so well last so long as they do - and the combination of this cylinder finish and long lasting piston rings helps achieve that but sometimes just results in a few lines in the bores that may make some miss-interpret as scoring - they are not - don't worry.
Of course other problems like poor oil quality, low levels, overheating, weak mixtures etc can make any piston expand and result in damage but when it does I have never seen it look like this so unless there is anything else to be concerned about - I think you are OK - your car is OK.
Happy days.
Baz
Baz, I am very relieved to read your in depth response and feel much better. I appreciate your input. I will be performing a compression and leak down test to finalize my decision (to keep or not). This car is my dream spec but I also don’t want to own a lemon.Unlike Lokasil or Alusil the GT3 models used the more expensive Nikasil plated alloy cylinders and despite the additional power of them and the similarly built Turbo's you never hear about cylinder problems because it is the very best surface finish available - it just costs more than the others - which a GT3 and Turbo price can accommodate.
In fact the construction is the same as our own replacement cylinders for Cayman S. 996 and 997 Gen 1 models that similarly do not score.
However the surface finish is so shiny and reflective that with modern boroscope cameras and lighting they can look as if they have scores - but it is only some polishing marks that have no depth and do not influence performance or long life.
Sometimes they are caused by the most minute change to the profile of the top edge of a piston ring (talking microns here) that just polish up one area more than another - still leaving far less wear, more round cylinders and better piston ring sealing than the original Lokasil cylinders did and better than the more improved Alusil.
This type of engine would have been a full race engine a few decades ago and rebuilt every few hundred miles and it is a great credit to modern production and Porsche that they can make something that performs so well last so long as they do - and the combination of this cylinder finish and long lasting piston rings helps achieve that but sometimes just results in a few lines in the bores that may make some miss-interpret as scoring - they are not - don't worry.
Of course other problems like poor oil quality, low levels, overheating, weak mixtures etc can make any piston expand and result in damage but when it does I have never seen it look like this so unless there is anything else to be concerned about - I think you are OK - your car is OK.
Happy days.
Baz
Again, thank you for your insight and your time reviewing my pics Baz.
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