confusion re. 05 boxster and ims
 

I have been looking at an 05 with 41 k,one owner,well maintained. it has a build date of 5/31/05. I inquired of flat6 innovations re. ims issues and got a reply that there were 2 styles of bearings,the later kind cannot be replaced. does that mean later 05(what defines later?)models don't have ims issues? if they do and one goes what happens next? thanks.

correct. i believe technically the cut off was for MY 2006, but those engines were used in some MY 05 cars. prior to that you could replace the bearing by extracting it. after that you must tear down the engine and ship off the entire shaft since there is no way to remove just the bearing. all engines with an IMS bearing have the potential for failure. just different ways to resolve them.

from LN Engineering's site:

Can I replace my IMS bearing?

LN Engineering offers three IMS solutions, two of which can be done without disassembly of the engine while the engine is still in the car:

single row IMS retrofit kit (fits MY02-05 M96 engines including some MY00-01)

dual row IMS retrofit kit (fits MY97-99 M96 engines including some MY00-01)

The last option, our IMS Upgrade, requires engine disassembly. The intermediate shaft must be sent in to us to be upgraded to our triple-bearing upgrade. A separate ceramic hybrid bearing upgrade is available for the late-style MY06-08 M97 IMS as well.

But before proceeding with an IMS Retrofit, you first need to identify which IMS you have!

How do I know which IMS my engine has and what can I do?

As long as the engine in your vehicle is original to the car, you can expect to find the following:

All MY97-99 vehicles with their original engines will require a dual row retrofit kit.

MY00-01 vehicles may need either a dual row or single row retrofit kit, so you'll need to inspect the flange, as shown below to be sure which will be needed.

MY02-05 will need a single row retrofit kit, although depending on how late the build date was, there may be some MY05 vehicles with the updated M97 IMS, which is not serviceable, at least without teardown of the engine.

If your vehicle has a replacement engine, expect to find the prevailing bearing used by Porsche in those years. If the engine was made for MY06 or later, it will have the late revision, larger IMS bearing which is not serviceable.

The 05 model year was the transition to the larger diameter "final solution" IMS bearing which cannot fit through the opening in the rear of the assembled cases. Problem is that there is not clear or definative "cut off" date, or list of serial numbers, for when this happened during 2005. All 2006's (or engines replaced during 2006 or later) have the larger bearing, some early 05's have the older style that can be replaced, later 05's have the "non serviceable" unit. If we get an 05 in the shop, the only way to know for sure is to pull it apart and look at the IMS bearing center nut, if it is 22MM, it is the larger bearing and cannot be changed.

And, yes, the larger “non serviceable” IMS bearing does fail.

I suspect that as the 2005-2008 Boxster/Cayman and Carrera cars IMS bearings are an expensive crankcase split excercise, the humble 986/996 variant will be worth more $$ in the (distant) future purely because its IMS bearing replacement is seen as a repairable item......

Maybe, but probably not. First, most buyers are unaware of any IMS issue; and even if they are aware of it, they ignore it for any number of reasons. Second, a fully informed buyer will know that there are 20 other engine failure modes that are just as serious that haven't been mitigated even if the IMS bearing has been replaced.