Khloesdad

I know its probably been discussed to death but to save myself time, does anyone know the engine number that tells you if you have the larger unservicable bearing? Was it late 05 production when this started.

groovzilla

The smaller more problematic IMS Bearing was used in the 997 early 2005 production cars. You can use this engine guide as a reference for both the 3.6L engine and the 1.8L "S" engine.
Here you go:

Engine#'s for IMS Bearing size:
The smaller IMS Bearing in the 3.8L motors are in motors up to M97/01 68509790 ---> Engine#'s from M97/01 68509791 and higher the larger revised more robust IMS Bearing.
For 3.6L motors, engine#' M96/05 69507476 and higher have the larger more robust IMS bearing

Khloesdad

Perfect. Thank you.

swish77

I'm going through this issue myself with my '05 Carrera 997, and those engine numbers are used as a guide only. They are not definitive. The only way to be 100 percent sure is a visual inspection. I've found confirmed cases online of late '04 production 911s (05 997 MY) that have the larger IMS bearing.

Khloesdad

There was a guy on FB looking for a reputable shop to replace his 997.1 IMS so I thought just maybe its not needed. I pasted the engine numbers so he could reference.

groovzilla

I'd have to disagree.
Many 2005 dated 997's were produced/manufactured in 2004 so the engine guide is quite accurate - There are also a few situations where 2006 dated 997's were produced in 2004 as well so the engine# guide is only way to confirm IMS size.
Also important to note, with 2005 engines having well into 70K - 90K miles these days, the IMS concern isn't as concerning as it was years ago when the engines only had 10-40K miles.

Khloesdad

If your not having issues then just have it looked at when its clutch time.

swish77

So, that would mean the engine numbers aren't necessarily sequential? For example, could a 997.1 with a December 2004 production have an engine number higher than, say, a 997.1 produced in February 2005?

groovzilla

There are examples of engine#'s not matching build/manufacture dates for various reasons - Engine swaps/replaced crate engines from factory which are left black(not stamped with a number).
Most engine numbers I have seen/checked on match up closely to build/manufacture dates. Only later engine I recall in earlier 2004 build date car was a replaced engine from salvage yard.