AT in engine number

[997_986]

Originally Posted by piper6909

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I thought my AT engine is the same as the original because I believe I've read on here that they are. It's not. And I don't want them to make the same mistake I did.

[...]

You're talking about parts matching, and that's an important and valid hint. The stupid thing about these AT-engines is that the standard parts catalogues may not be valid. The only good thing is that you (mostly) get an updated unit in parts. But there can also be weird things in these motors, I am quoting from an engine rebuilder:

"Due to production problems, the first 2.5 litre boxster engines had some engine housings in which the cast-in Lokasil mouldings were mechanically removed after casting. New cylinder liners were then shrunk in. Some of these engines subsequently had problems with cylinder liners shifting downwards towards the crankcase. At some point, the liner had moved so far down that the top piston ring jumped behind the top edge of the liner. This of course led to
engine damage."

[Homeoboxter]

Originally Posted by 997_986

"Due to production problems, the first 2.5 litre boxster engines had some engine housings in which the cast-in Lokasil mouldings were mechanically removed after casting. New cylinder liners were then shrunk in. Some of these engines subsequently had problems with cylinder liners shifting downwards towards the crankcase. At some point, the liner had moved so far down that the top piston ring jumped behind the top edge of the liner. This of course led to
engine damage."

Exactly how my engine fell apart. It's kind of off topic, because these engines (mine at least) did not get an AT number.

On the other hand, I have an AT engine from a Boxster S which has the non-servicable IMS bearing, and thus definitely different from what it came out with from the factory originally. So, Piper raises a valid point.