daviddbohn

Hi,
I have a 1999 Carrera 996 that had the engine replaced in July 2010. The engine number is M96 / 01AT66X67414. How do I determine what IMS bearing is in the replacement engine and the probability of failure.
Regards, David

ssherman68

I think there are some others that know a lot more about this than I do. But when I was looking for a car, I did come across one or two with a replacement engine & did some research. If yours was replaced in 2010, it most likely has the more robust 997 style bearing. However, it's possible that particular engine was older and had been sitting on the shelf for a while. If so, It might have the less robust 996.2 single row bearing.

Short story - To be totally sure, you would probably need to talk to a dealer and give them the serial number. Maybe they could give you the build date on the engine and an opinion on the style of IMSB in it.

hatchetf15

OP - Best info I can supply is your engine serno is 1,000 “AT” rebuilds into the period when the new, unserviceable bearing was used. So 99.9% sure that’s what you have.

808Bill

Why?

dbwisle

please explain ? What do you mean by 1000

Optionman1

Use the example below to decipher your code:

The engine number M96/03AT665 68531 translates to...

M96/03 = 3.6L motor

AT = denotes factory replacement engine

6 = 6 Cylinders

6 = Natural Aspirating Motor

5 = date of manufacture = 2005

68531 = actual serial number

911 CARRERA M96.01 1998 W 66W 00501>60000 6ZYL/3,4L /220 KW /300 hp
911 CARRERA M96.01 1999 X 66X 00501>60000 6ZYL/3,4L /220 KW /300 hp

Optionman1

https://rennlist.com/forums/996-foru...ecode-sat.html

info in this thread might help you as well. similar discussion about IMSB

Dr_Strangelove

@daviddbohn - look for the casting stamp in this post on your own car: https://rennlist.com/forums/996-foru...ing-stamp.html

I explain how to decode the stamp in post #2, this will tell you the day that your block was made. What this does not tell you is what day your engine was assembled, hence, it will not tell you which IMSB is inside your car. It will be a clue, however, if the date falls well within a specific range. Say for example, if the block were cast in 2008 we can pretty safely assume it has the updated single row bearing that cannot be pulled.

hatchetf15

OP - M96 AT 65993 was built end of Nov 2004. M96 AT 66526 is the earliest example I can find with the 22mm nut mentioned (unserviceable IMSB size).

Pencap914

So from my engine serial number, I must have an early remanufactured engine, my guess would be sometime early 2004 or even 2003 with a 5204 or 6204 IMS bearing.

Serial number on my engine is M96/04AT66Y65546, so unfortunately for me number 65546 is 980 away from the earliest example you've seen with the M97 style 6305 bearing.

FYI my 996 that I previously owned had engine serial number M96/01AT66X67023 which I confirmed had the larger 6305 bearing.