Dreaded IMB question, with a twist.

Recently I bought an 2004 C2 cab. It had a IMB caused engine failure which was fixed by the local Porsche dealer in 2012. My questions as a non-insider: Is there a chance that Porsche put in an "upgraded" IMB to replace the failed one? What is the chance that the new IMB breaks and would the LN upgrade be advisable at this point?

Did it require a new engine? That's the typical fix for an IMSB failure. It's most likely a single-row IMSB in the new engine, and not really upgraded. The LN Engineering IMSB would probably give you a little more peace of mind.

No new engine but 8 pages long list of parts replaced. Failure happened when starting the engine at low rpms.

Checked the part list for a new IMSB?

How many miles were on your C2 in 2012 when the failure occurred? Mark/Pelican Parts

Yes, a new imsb is on the list. The car had approx. 44k miles on it.

Quotes source post: 10688943

What does this exactly mean? I thought all engines started out from 0 rpms?

How many miles now? IOW how far since the repair? All M96 engines have an IMS bearing. Therefore all can have an IMSB failure, new , old, dual-single row, larger dia, LN, Casper labs, Pelican, etc... Drive it enjoy it Change the oil every 5k miles.

That is odd. Maybe we're all starting ours wrong? This would explain everything!

DrBrain, You are getting all of these questions due to the understanding that if an IMS bearing went bad, regardless of any catostrophic damage to the rest of the engine, the dealer would just pull the motor and put a new one in (provided that Porsche chose to cover the issue). I've nver heard of a dealer rebuldling an engine in house after a IMS bearing failure.

I don't know if they put in a new engine, "rebuild" is the term that the Porsche service manager used. It is entirely possible that they put in a new one. BTW, the repair was covered by an extended warranty.

Quotes source post: 10689390

I would bet the 3rd party insurer had them source a used engine and the parts list you have is all the things they needed to replace on the used engine. All of the replacement engines put in by dealers were factory rebuilds, If I remember correctly.

I doubt the SM would write rebuild if the engine was replaced. It is not unknown for a dealer to rebuild an engine that has suffered an IMSB failure as long as the engine is rebuildable. The factory issues guidelines the tech is to follow to determine if the engine is rebuildable. I came across one such engine at a Porsche dealer. Besides the obviously bad IMSB the IMS was replaced along with one cam chain tensioner rail for the loose IMSB caused some excessive chain movement which damaged (but not severely) the rail (broke off some fragments of the composite plastic material these are lined with).

Quotes source post: 10688929

I don't think we answered your questions: By 2012 Porsche only replaced a 2004 engine's IMS with the larger, single row, upgraded (post 2005) IMS shaft and bearing assembly. It is/was very rare for the dealer to rebuild an engine. Most failed engines were replaced with "new", actually factory rebuilt, crate engines. In those cases there won't be many parts on a replaced parts list. If the car had a Porsche rebuilt engine installed it will Have an "AT" in the serial number. Like this: M96/03AT66565123 M96/03 = 3.6 AT = Factory Rebuild 665 = 6 cyl, normally aspirated, 2005 "AT", which is not the normal format, might stand for "Austausch", which means "rebuild" engine. http://www.renntech.org/forums/topic...e-sn-decoding/ If you have the new, improved, larger diameter bearing it cannot be changed without complete engine disassembly.

I had a factory rebuilt engine put in my car by the Porsche dealer. The total number of pages was 2 because the part being replaced was the engine. It didn't come nearly close to 8 pages. 8 pages seems like engine was torn down and individual parts were replaced.

Is there a consensus on how well the new Porsche IMS bearing holds up? Other than larger size, what is different about it than the early bearings? My '01 C4 received a new shaft and bearing with a major engine repair in late 2011. I was told that the bearing is the "new" Porsche bearing that requires the engine to be spilt in half to install.

I was told the same, that its a "new type" of bearing. Don't know if this is BS or not. After 2K miles with my car I am happy as a clam. If I wanted to have a cheap and worry less but dull car I could have stayed with my Acura. Life is short, enjoy. Will be posting pics soon. I am in process of upgrading the stereo with a Pioneer DEH-80PRS or DEX-P99RS, Polk audio Amp and Morel speakers, will report here.

Bravo! Good answer. The 996 is not the be all and end all of cars, but for bang for the buck, coupled with fun to drive, that certain "it's a Porsche 911" feeling, and the relatively low cost of maintenance and upgrades, it's right up there!

Two months later, finally something to update. Went to my independent Porsche mechanic (DBS Tuning) for clutch replacement. While doing it they saw that the IMS was replaced with the "new type" of that part, that is not serviceable without splitting the engine (wanted to put in a LN solution bearing). However, it was not sealed properly and was leaking. Is that a good thing to have the "new type" of IMS. I have now the receipt for the original repair done by the dealership. Can anybody tell me what those other expensive items are, one for 1231.82 (part # 1 996-105-901-04 AS)and another for 633.57. Looks like they tore apart the motor. Can't upload pics from my computer, hmmm. BTW! Pioneer DEH-80PRS along with Hertz ESK 165 (original sub modified but retained), driven by a Polk 5 channel amp sounds great.

If you have the larger non-serviceable IMS, you might want to look into the DOF kit. A bunch of 997 guys have been doing this recently. Here's one example: http://www.pedrosgarage.com/Site_2/TechnoFix_DOF.html

Quotes source post: 10816323

Stock Code 996-105-901-04 Is the entire intermediate shaft.