Thanks to Michael - Dallas for sending this my way.

With the introduction of the Boxster Porsche teamed up with Kolbenschmidt to manufacture their newly designed water cooled engine. These engines were to utilize the newly introduced Lokasil liners. The liners themselves offer a higher friction free service area . This is most useful in not only the longevity of the cylinder but in the ever growing higher mileage service interval. The cases experienced several issues starting with their porosity . In 1997 many of these newly released engines would seep oil through the cases themselves. This seepage was due to a problem in the manufacturing process. When the cases are made in a high pressure die casting the air in the die has to escape. Should the alloy enter to fast and not let all the air out you would have trapped air pockets. These pockets produced a porous area in where they were. This area would then allow seepage of the oil. The reason it would generally be oil and not coolant was due to the casting process. The air would be trapped in the bottom to center rear of the castings in which housed the oil.

Another well known problem was the liner failures in late 1998 to early 1999. This would have affected the 1999 model year cars only. These failures were also due to a manufacture process of the crankcases or engine blocks. The cylinder liners are made of an alloy made abrasion resistant by adding silicon. Prior to casting the crankcase, the cylinder liners are fixed in position by an operator , then surrounded by a conventional aluminum alloy casting. This is done by inserting the preformed cylinder liners manufactured by Plochigen-based Ceram TecAg in a special freeze casting process into the die. The dies are then closed and a high pressure die casting (HPDC) and squeeze casting (SC) are utilized to achieve this. Three casting machines with a closing force of 1,800 tons are used for this purpose. The advantage of the Lokasil process is that the silicon required is applied only where it is needed. Lokasil base material cost less than Alusil and is easier to process. These liners or preforms are of high silicon content of 20-27% and offer a high reduction to friction. Kolbenschmidt holds the patent to Lokasil and is also known for their Alusil and Galnikal piston liners. Lokasil is a "sacrificial" bore liner comprised of silicon fibers in a binding that, when inserted into the block mold, burns out the fibers, leaving the high-content silicon surface directly in the bores. This actually allows the “sacrificial” liner to become one with the block thus eliminating a separate part in the block.

In 1998 Kolbenschmidt had dropped the casting machine while it was being moved. Do to the time to repair the machine Porsche was in a bind. This could slow the Boxster production down severely unless a fix was found. Kolbenschmidt had suggested using the failed quality controlled (QC) blocks they had. Most of these blocks had casting defect or a porosity problem in at least one cylinder. The fix was simple and by all means acceptable to standards when done correctly. What they suggested was to re-sleeve the bad cylinders. Porsche accepted and Kolbenschmidt began the process of the repairs until the casting machine issue was fixed. This process would start by boring out the failed cylinder to allow for the insertion of the liner. There is also a groove cut around the top of the cylinder to keep the sleeve from dropping. This groove is approximately 2.0mm larger in the size of the cylinders width and goes down approximately 4.5mm. Now the next step was the insertion of these liners. It was decided to press the liners in the blocks. This is where the error occurred. Some of these liners were pressed in at a higher rate than the top retaining ring could handle. This would then fracture the ring at the top of the liner. When this ring failed under operating conditions it would be catastrophic. The ring itself would fall apart inside the combustion chamber. At this time the piston would force this debris up into the cylinder head. The piston rings would grab the liner and pull it down from the momentum of the crankshaft. Some of these engines would be replaced from coolant loss before they totally self destructed in this fashion. This was do to the ring starting to come apart but not fully. This would compromise the sealing of the head gasket and cause the coolant to either be burnt or expelled from the combustion pressure.

Porsche has not divulged exactly how many engines this actually occurred in other than a broad range of 2.5 engines in late 1998 -early 1999 . Nor have they released any engine numbers that have had sleeves installed. Generally speaking the problem would occur within the first several thousand miles. They have been very good in correcting this for their customers in and out of warranty.

 

hmmmmm i hope my 99 doesn't have any problems haha

 

Well , when and if my motor goes, I'm going to personally track down the guy who dropped the machine and hit him with the failed pices. Klutz!!

 

That's a great write up +1 for u...

 

I don't know if there is any truth or how true the article is, but the actual author is a PCA technical advisor. I would certainly hope this individual is a wealth of knowledge and did his homework.

///Michael

 

That's interesting! I didnt know that. Good post!

 

thanks for the write up! very informative.

 

That is the same text as is included in Streathers 996 book. Don't know who the author of the article was. On Rennlist, there was a torn down '99 motor where it was obvious one of the sleeves was totally different than the others. Someone commented that the motor had been reworked, and the OP stated he was the original owner and the motor had never been opened. Must have been one of the those motors.

 

interesting...

 

What page? I haven't seen this text.

 

It may have been in the long Autofarm article that was linked a while back, but I thought it was in the Streathers book as well. I'll look when I get a chance. I know I've read the exact same article before