Considering 996 C4

[Don Smethers]

Have owned many Porshes since mid 60's, none at this time but shopping. Considering a specific early 2000 996 Carerra C4. Is there a way to determine for certain from the engine serial number whether it has the dual-row IMS bearing (from the factory), or the single-row IMS prone to failure?  Thank you.

[jimalthoff]

Based on all the info i have read, you can't determine the ims being used from an external examination. Only a tear down.  It is pretty doubtful that a 2000 has a double row bearing since the majority were only placed in 1999. Also, if the engine was replaced,  whatever ims bearing that was available at that time was used. So, it could be one of three types.

[Don Smethers]

Thank you. That is what I have learned as well. I'm really trying to give the 996 seller the benefit of extra research, to prove (or ?)  his statement that this has a factory big bearing IMS, 'according to the engine serial number'. Really hoping to find some reliable factory records that would confirm that, cause it's very cool ride, otherwise not.

[JFP in PA]

2 hours ago, jimalthoff said:

Based on all the info i have read, you can't determine the ims being used from an external examination. Only a tear down.  It is pretty doubtful that a 2000 has a double row bearing since the majority were only placed in 1999. Also, if the engine was replaced,  whatever ims bearing that was available at that time was used. So, it could be one of three types.

 

Welcome to RennTech

 

Most 2000 and many 2001 M96 engines were dual row engines, which created the problem that the only way to know which style was used was to pull the transmission, clutch, and flywheel and haves a peek.  There is no other proven method to tell you which version was used during the 2000-2001 transition period.  If the engine was replaced with a factory unit, it would carry the letters “AT” on the engine number on the sump rail, and the number will reveal its year of assembly; all reman engines produced after 2004 carry the oversized non serviceable third design IMS.

[Don Smethers]

Thank you for your replies. Agreed, on this specifiec car, if there are no records of an engine replacement or an IMS upgrade, then the safe assumption for a 2000 is that the small single row bearing is in the engine. Of course, since the factory didn't know of the failure rate until later, there may not be an engine-by-engine record kept or being accessible at this time. Does this sound right? So, I'm still shopping for my next Porsche.

Edited June 6, 2020 by Don Smethers

[JFP in PA]

32 minutes ago, Don Smethers said:

Thank you for your replies. Agreed, on this specifiec car, if there are no records of an engine replacement or an IMS upgrade, then the safe assumption for a 2000 is that the small single row bearing is in the engine. Of course, since the factory didn't know of the failure rate until later, there may not be an engine-by-engine record kept or being accessible at this time. Does this sound right? So, I'm still shopping for my next Porsche.

 

Your assumption that the 2000 is a single row is flawed, while this is some possibility it is a single row, experience says more 2000 were dual rows than singles.  Again, the only way to know for sure is to look.  You can also look for the engine number stamped into the pan rail, it is contains the letters “AT”, is is a replacement engine, and the rest of the numbers will tell you what year the engine was assembled, as well as what size engine it is.

 

Probably the best advice I can give you is to find a car in the condition and with the options you want, and then have a competent shop do a pre purchase inspection (PPI).  While this will cost some $, it should also tell you about if the engine assembly date coincides with the model year of the car, or if it has been replaced.  It will also outline factors like how many times the engine has been run to the red line, and a myriad of other factors about how the car has been maintained and run. That data is a MAJOR factor in sale price negotiations, and can also prevent you from buying someone else’s problems.  We once had an absolutely beautiful 996 in the shop that looked like it had lived in a plastic bag for the last several years; only problem with it was that it had a 2.7L Boxster engine in it instead of what should have been there, which explained the prospective buyer’s comment that is felt sluggish on acceleration when he test drove it.  Used Porsche’s are definitely a “buyer beware “ proposition..............

[DBJoe996]

As said, for a 2000 it probably is a dual row IMSB.  But if the engine serial number has an AT in it, then the original motor has been replaced and you cannot know what type of IMSB is in it.  Only physical inspection will reveal what is there.  The good news is if the IMSB is dual row or single row, then it can be replaced with the LN Engineering IMSB Solution and you are done with the issue forever.  However, if it is a AT replacement engine with the larger IMSB (later replacement engine years) that can only be replaced by disassembling the engine and splitting the engine casings. But, also, the larger IMSB is not problematic with proper oil changes and change intervals.

[JFP in PA]

55 minutes ago, DBJoe996 said:

As said, for a 2000 it probably is a dual row IMSB.  But if the engine serial number has an AT in it, then the original motor has been replaced and you cannot know what type of IMSB is in it.  Only physical inspection will reveal what is there.  The good news is if the IMSB is dual row or single row, then it can be replaced with the LN Engineering IMSB Solution and you are done with the issue forever.  However, if it is a AT replacement engine with the larger IMSB (later replacement engine years) that can only be replaced by disassembling the engine and splitting the engine casings. But, also, the larger IMSB is not problematic with proper oil changes and change intervals.

 

There is some leeway in that analysis; if the engine has the AT in the number, record the number as it will tell you what year it was assembled.  If it was earlier than 2004, it would have the IMS bearing appropriate to the year, if  the year was 2004 or later , it definitely has the non serviceable bearing.

[DBJoe996]

5 hours ago, Don Smethers said:

Thank you for your replies. Agreed, on this specifiec car, if there are no records of an engine replacement or an IMS upgrade, then the safe assumption for a 2000 is that the small single row bearing is in the engine. Of course, since the factory didn't know of the failure rate until later, there may not be an engine-by-engine record kept or being accessible at this time. Does this sound right? So, I'm still shopping for my next Porsche.

Look for a 98/99 996 from Southern California. Dual row IMSB, stout and robust, no rust.  And like JFP said, give us an engine number and we will dissect it to the nth degree 🙂  I have a 99 manufactured in 7/98 with 145K + miles.  I do regular oil/filter changes twice a year and I do not worry about my IMSB at all.  I got an LN spin on oil filter adapter and magnetic plug.  Never anything on those to give me problems or reason for concern.

[Don Smethers]

Thanks DBJoe996 for the offer to dissect the engine #.

Here's the engine # M96/J466Y14721.  Seller says build date 4/2000.

If this comes out to be the double row IMS, then I would really appreciate getting documentation to keep with the records. I don't know where this doc exists, if we can pay for such records, etc. 

[DBJoe996]

I don't understand that engine number.  Here are examples of engine numbers:

 

 

Edited June 7, 2020 by DBJoe996

[DBJoe996]

Here is my 99 Model Year M96/01 engine number.  Per the above chart, a 2000 should have an engine number M96/0466Y....

 

[Don Smethers]

Thank you for your reply and the engine number chart. Agreed, the number provided by the seller is incorrect, and the photo provided is not a clear shot. The 'J' could well  be a '0'. The first setp in a PPI would be to clairify this. Let's assume for the moment that the correct number is M96/0466Y14721. How does this relate to known information on the IMS? Again, thank you for your time.

[DBJoe996]

In 2000, Porsche C4 production (for coupe) was 3,862

Source -

Porsche 911 996 Production numbers by year and version

HOWTOPORSCHE.COM

---

Porsche 911 996 productioni numbers for all versions by year. Model No. built 1997 Carrera Coupé:14 1998 Carrera Coupé : 8296 1998 Carrera Cabriolet : 952

Your engine number is M96/04  66Y 14721

One thing that would be helpful is a picture of the door frame sticker that shows the actual date of production.  For instance, my car was sold as a 1999 C2 coupe, but was made 7/98. Maybe you can get that during the PPI

 

[Don Smethers]

Thanks. I'll see if I can get the door sticker pic today. Seller says build date 4/2000. Does the information provided thus far get you to the IMS information?

[DBJoe996]

Here is a picture of my door sticker

 

[JFP in PA]

3 hours ago, Don Smethers said:

Thanks. I'll see if I can get the door sticker pic today. Seller says build date 4/2000. Does the information provided thus far get you to the IMS information?

 

AGAIN, regardless of the date of manufacture, exactly which IMS design is in any given 2000 or 2001 M96 car can ONLY be determined by pulling it apart and looking.  I have two M96 engined cars in my personal fleet, the 2000 is a very early production date, the 2001 a very late production date..  Both have been converted to IMS Solutions, but the 2000 is a single row engine, the 2001 is a dual row; exactly backwards from what the production dates would suggest.  It is probable that many, but not all 2000 M96’s would be a dual row, but over the years of retrofits, I have seen enough that were not to realize that while the percentages favor the 2000 being a dual row, it is NOT a guaranteed outcome............

[Don Smethers]

OK. thanks for the help.