It is my understanding from local Porsche dealer that engines with updated IMS bearing started with serial # 61507476 (although I suspect the 1 might be an 8).

 

http://www.lnengineering.com/ims.html

According to PET, here are the engine numbers for single or double row bearings* up until late 2005 then 2006 and later engines which received a larger, non-servicable single row bearing. *Courtesy of Scott Slauson http://www.softronic.us.

Boxster: Double Row: up to 651 12851 (M96.22) up to 671 11237 (M96.21)

Single Row: from 651 12852 (M96.22) from 671 11238 (M96.21)

996: Double Row: up to 661 14164

Single Row: from 661 14165

 

Clearly, you're only talking about 3.6 liter engines. (They remain known as M96 engines). The Carrera S engines (997.1) are all known and marked a M97 engines.

 

I am confused by the technical jargon in response to my earlier post. I am interested in a 2005 997 with engine number 68504875. Does it have the updated IMS bearing? Thanks, Gary

 

This is the first time I've ever seen a post with a reference to an engine number for the '05s that is suppose to have the improved IMS bearing. But I do believe the second digit should be an 8 if it is a C2S model or 9 if a standard C2.

This quote is from another thread and is the closest thing that I've read to decode the engine numbers:

The following response only applies to the 996 Carrera and older Boxsters. It's not helpful for a 997 '05 buyer, ignore these numbers:

So if you are looking at a 2005 997 S model AND if your dealer is right (who knows?), then numbers after 68507476 should be safe. In which case, the car you are looking at, 68504875, would NOT have the newer IMS.

But I'm not sure if I trust your dealer. First of all that "1" isn't right. Second, the '05s that got the newer IMS are suppose to be later model '05s, 07476 seems like it would be too low a number.

 

The ONLY way to really know is a visual inspection of the IMS bearing flange. We have experienced more than one occasion where the engine number did not indicate the actual bearing that was installed at the factory.

The records that Porsche kept have been sloppy at best.. I choose not to use them for anything more than a general idea of the time the engine was made, because the IMS thats used could be anything.

The "new" IMS isn't necessarily a good thing, because they are failing too, BUT they can't be changed like the earlier M96 engines as the bearing in the later design is LARGER than the access port in the crankcase. If the bearing in one of these engines begins to fail, the engine is compromised because the bearing cannot be changed.

 

jake, any idea cost of changing bearing in earlier 95 engines? will doing so make them bullet proof or at least less prone to failure than later cars (at least until 09 when bearing is no longer issue)? thanks, gary

 

To my knowledge (I've seached before), there hasn't been a single first hand report from a 06-08 997 owner on this forum of an IMS failure. Just the very occasional second hand report, which is hearsay IMHO. I'm not saying it can't happen, but if it has, it seems extremely rare. The vast majority of the reports seem to be coming from the 996 forum and 986 Boxster forum.

 

Not only this forum. On the internet in general, I haven't found a single authenticated first hand account. Like you, I also believe it's smart to dismiss second-hand reports such as "I was at my local Porsche dealer and saw an '07 in the shop with a blown IMS", or claims from anyone with an entrepreneurial stake in fanning the flames of fear. In fact I've only found a couple first-hand reports of '05 997 with IMS failure, and as I recall from what industry people were saying at the time, Porsche sold a lot of them that year.

But let's say the '06-'08 are having IMS failures. That would imply that beefing-up the bearing, bearing shaft, and the IMS shaft itself (the shafts are half again thicker in diameter) is not an adequate solution...so why should one expect the same strategy from LN to yield different results?

 

Thats because most of the cars have failed while under warranty and the issues were never divulged..
Also, it took several years for IMS issues with M96 based engines to show up..

The sad part is when they show, they can't be repaired, no matter how early they are noted.

The earlier engines with the LN bearing thats used as a retrofit are benefitting from the ability to have the bearing changed, even at a routine mileage point. 18 months ago EVERYONE said these bearings could not be pulled. I carried out the first procedure using the LN Hybrid bearings with my hands in my shop, 30 feet from where I am posting this. The ultimate upgrade comes when I reconstruct engines using the LN triple row bearing, make my shaft mods and alter the sprocket hubs. In this situation the etire shaft is upgraded, which does require engine disassembly and reconstruction.

 

You're implying they were divulged to you...are you claiming to have insider information as to warranty claims from within the Porsche organization?

 

That's incorrect.

The M96 engines included all 2.5/2.7/3.2/3.4/3.6 and 3.8 engines (non GT3/GT2/Turbo) up until approx 2006 - including the 997.1 Carrera S engines. The M97 superceeded the M96.

Here's a great discussion of the subject featuring Tony Callas and Jake Raby:

https://rennlist.com/forums/showthre...ferrerid=21390

Cheers,
Joe

 

after reading jake's detailed 12 page "experimental" multifaceted approach to solving the potential problem "without warranty" using the LN engineering retrofit, I THINK IT BEST I NOT BUY AN EARLY 2005 997 and i feel sorry for those that did. if indeed the IMS issue is as bad as it might be, PORSCHE should extend its warranty into perpetuity or go F itself. if not, they should stand up and scream that the IMS issue is a bunch of B.S.

 

MY06-08 cars are indeed having failures, but there are not a large number of them that are out of warranty, as reported by independents and P dealerships I work with.

Porsche's fix was not the right one. The bolt isn't breaking, it's the bearing that is failing. They made the problem worse by going to a larger diameter bearing, which slows the speed of the bearing down further. Speed is a ball-bearing's friend. Secondly, Porsche's bearing is still a conventional bearing, susceptible to the same problems of the earlier bearings due to poor lubrication and corrosive wear of the ***** due to combustion byproducts, fuel dilution, and moisture.

This is all explained in detail on our website as to why we chose to use a ceramic hybrid ball bearing. The speed issue is also explained as to why we go to smaller diameter bearings on our IMS Upgrade.

 

But as long as the shafts (bearing and IMS) remain intact, that would at least forestall the catastrophic damage to the engine, would it not, and allow for a rebuild vs replacement situation?

I'm sorry but that's simply not true. Are you actually an engineer??? The bearing rotates at the same speed as the shaft, which is a fractional function of engine speed. The bearing could be as large as the earth in diameter and it would still turn at exactly the same rpm as a bearing the diameter of the shaft itself...or smaller, if that were possible.

Again, not true, at least not completely. It sounds like you're repeating something an engineer told you, but that he perhaps didn't completely explain. The phenomenon you describe on your site does indeed come into play; however it is only one factor among many, and typically not the major factor in bearing wear, since it applies only in the case of a theoretical where all other parameters are at their ideal. Once the tolerances have been compromised (such as from lack of or improper lubrication) and there is any slop, an increase in rotational speed translates to increased wear and a hastening of failure. Running an engine at higher rpms than necessary will cause more wear throughout the entire system, so doing it simply to try to prolong the life of a single bearing would be ridiculous even if it worked, which it won't. If "tracked" cars exhibit less IMS failure it is most likely due to more frequent oil-changes and/or less lugging. I would agree that driving at lower than ideal rpms will strain any drivetrain component (including the IMS) that is not running absolutely true.

That statement is factual. The problem with your "solution" however, is this: The engine was not designed for the IMS bearing to receive crankcase lubrication. Merely removing the seals does not assure that the bearing will be bathed adequately. If it happens, it's pure luck. That said, unlike the OEM bearings which are designed for high-viscosity (grease) lubrication and can never be adequately lubricated by oil alone, at least your retrofit is designed for oil lubrication, and the type of materials you chose are resistant to wear in an environment of less-than-ideal lubrication. Bottom-line I do concur that your retrofit bearing is better than the '06-'08 OEM.