Confirmation of replacement engine?

[aaronjb_ME]

My 1999 996 has a build date of 3/98. However, the engine is stamped with M96/0166X15601, indicating a 1999 manufacturing date for the engine.

The VIN analysis that I purchased from Stuttcars says the engine code should be M96/0166W08070. Can I take this, along with the above date discrepancy, as confirmation of a replacement engine?

If so, what am I to make of this? I thought all engines replaced under the auspices of an official recall or Porsche-approved replacement plan are stamped with an AT in the engine code.

Any analysis from the experienced crew here is appreciated.

[looneybin]

Could have been replaced with a wrecked donor car motor

[aaronjb_ME]

Thanks. I'm thinking the scenario was something like that.

If it was a replacement engine installed "officially", so to speak, it would have the AT in the engine code, right?

[looneybin]

Correct, factory replacement motors have “AT” in the number

[tonythetarga]

The AT engines are the style with the non-serviceable IMS bearing, meaning that they are the same as the early 997’s. If the failure to the original engine came sooner than the development of the next gen engine, that could also explain the number discrepancy. Or, as explained in the earlier post, it could have been out of warranty and the owner may have purchased a used engine.

[BYprodriver]

Originally Posted by aaronjb_ME

My 1999 996 has a build date of 3/98. However, the engine is stamped with M96/0166X15601, indicating a 1999 manufacturing date for the engine.

The VIN analysis that I purchased from Stuttcars says the engine code should be M96/0166W08070. Can I take this, along with the above date discrepancy, as confirmation of a replacement engine?

If so, what am I to make of this? I thought all engines replaced under the auspices of an official recall or Porsche-approved replacement plan are stamped with an AT in the engine code.

Any analysis from the experienced crew here is appreciated.

Lot's of problems with the early 3.4 litre engines, lots got replaced before the AT program.

[aaronjb_ME]

Ah, interesting. Thanks for the replies. I didn't realize the AT-stamped engines came later.

This is all very interesting, and I'm going to see if I can tell when the engine was replaced.

[Norm101469]

Where would the AT stamp be located on the engine??

[tonythetarga]

It is part of the engine serial number by the oil sump. If you look up engine numbers for a 996, you will find the series of number and letter designations for each year of production. Instead of the production tear letter, it has AT in the series and can be used for a number of model years.