stairmasterman911

I realize that M97 engines can have smaller IMS on engine number 68509790 and below, and larger ones with engine number 68509791and above, but my car has a number that confuses me. It's M9701 68515383. I was under the impression that it's only the last four digits that tell you the IMS size. Any help? Thanks in advance.

SoCal C2S

semicycler

There are three different serial number types for the three engine variants in our cars - base model M96.05 3.6L engines, S-model M97.01 3.8L engines, and the X51 power kit M97.01S 3.8L engines. All three have slightly different engine serial number formats.

For S-model non-X51 M97.01 engines the serial number is of the format M97/0168YXXXXX. The last 8 digits matter and are the following format:
685XXXXX = M97 for MY05
686XXXXX = M97 for MY06
687XXXXX = M97 for MY07

So the first two digits are 68, followed by the year digit, followed by a five digit serial number. But the full serial is M97/0168YXXXXX.

For X51 engines I believe the format is M97/01S68YXXXXX (added 'S' between 01 and 68).

3.6L base engines have a similar format M96/0569YXXXXX (not positive on the 05, can someone check?).

With replacement engines there is an 'AT' in front of the final eight digits. So a S-model 3.8L factory replacement engine the format would look like M97/01AT68YXXXXX.

For your 2005 you want to look at the last five digits for sequential build serial number (15383 in this case) to compare against the class action lawsuit cutoff serial number (09790). Based on that you have the larger bearing. But there are exceptions. The only real way to tell is to drop the tranny and inspect the size of the IMS mounting flange. 2006 and up have the larger one regardless of serial number.

edit: I haven't checked the 09790 vs. 09791 cutoff serial number, I just used your post #1 as the reference.

stairmasterman911

Thanks Semi! So, it's really the last 5 digits -- that's where the confusion was coming from.

Escobar19

If you take a clear look at the numbers you can easily understand what is the problem, from numerology https://www.sunsigns.org/ point of view this is not very bad, but also not good. You can easily read by yourself and discover the meaning of this without asking anybody.

johnmlevin

Hello all!

Sorry to extend a long thread, but I am trying to decipher a VIN on a 2006 C4S and I am confused based on this discussion, and identifying its IMS bearing as being either Large or Small...

Here are the end of the VIN:
9956S768445

jhbrennan

Need the engine number not the VIN.

johnmlevin

Ah! Apologies!

I thought the list posted earlier in the thread was designed to help decipher the pertinent serial number info on the engine from the VIN:

street rod

All 2006 - 2008 cars have the larger bearing.