Row

2006 Porsche 911 Carrera S, M97 Engine, 49k miles. No Engine Problems.

useridchallenged

997.1 2005 C2 (November 2004 build). Daily driver, spirited driving and autocross.

Failed April 2009 after 68k miles and 4.5 years. Fragments from IMS bearing caused oil scavenging pump to seize, gear snapped off pump and broke a hole through the valve cover. Replaced with new crate motor after much negotiation with PCNA and dealer since vehicle was well out of warranty (time and miles). I suspect the crate motor has the larger single-row bearing (late 2005 to 2008), but unconfirmed.

Now I tear open oil filter after every oil change to look for metal particles, and have magnetic drain plug. Currently have 40k on crate motor (108k on car) and things look okay so far. Will upgrade the IMS bearing at 118k (50k on crate motor) to LN Engineering bearing (rated for 75k miles). Might be costly since it requires engine disassembly, unlike 2000 to early-2005 motors which can be serviced without a rebuild. Still cheaper than a new engine, right?

Petza914

If your replacement motor has the larger IMS bearing, unless you're heavily tracking the car, there really isn't any reason the tear down that engine to change the bearing. The odds of the larger bearing failing are likely lower than something getting messed up during the rebuild. Now, if you want to have the transmission pulled and check to verify that you do have the larger bearing (if you don't know 100%) then that might be a $1,000 labor bill that's worth it and if it's not the larger bearing, replacing that one with the LN upgraded smaller diameter bearing (another $1,000). In either case, you'll have the peace of mind that you have the larger bearing and if you didn't, the peace of mind that you upgraded it to something better.

useridchallenged

Rumor has it that although the larger IMS bearing from late-2005 through 2008 is more durable and should not fail in low RPM street driving, its life will be shortened significantly under high RPM race conditions. The early-2005 IMS bearings actually prefer high RPM driving.

The LN Engineering bearing for the late-2005 through 2008 engines can be raced, but it also costs $15k to install. If you want to race - and I do - the only choice at this point is to upgrade to a 2009 or later (could be worse), which costs about the same as selling the 2005 and taking the savings of the LN upgrade and purchasing a newer Porsche.

To all the 1997 to early-2005 Carrera/Boxster owners who want to race: upgrade your IMS bearing now ($2500) before it fails ($15k-20k for a rebuild).

This survey would be better if it was explicitly limited to pre-2009 cars, and was limited to cars with over 50k miles (the approximate rated life of the IMS bearing) or even over 100k miles. What are the odds that the IMS bearing will ultimately fail if you wait long enough? Is there any correlation between racing and IMS bearing failures? Those are the statistics I'd like to see.

useridchallenged

My new crate motor after IMS bearing failure at 68k miles.





Crate motor.

DoninDen

Sorry that you had your IMS failed. The good news is, I've never seen a substantiated claim on here that a larger IMS bearing has failed. By unsubstantiated, I mean, there have been the occasional and very rare post by someone who says it happened to a large bearing 997, but then they never respond to questions and it's usually their first and only post. So the claims appear to be from someone trolling. I would just guess if someone had just lost their engine and reach out to post about it on a forum, they would be looking for answers and want to share their story.

It's likely that, just like any bearing, eventually the larger bearing could fail. Given the number of posts and subscribers on here and on sixspeed, to date it doesn't appear to have happened. The high RPM comment, I'm assuming means over revs. Lots of 997's hit the track, but there haven't been posts to support that. If the rumor is from your mechanic, there are lots of mechanic's wife's tales.

useridchallenged

The high RPM comment refers to when you are sustaining high revs for a substantial period of time, not just a blip as you are accelerating between gears or a brief over-rev.

My mechanic took a look at the IMS bearing in the above picture of my crate motor, and confirmed that I in fact have the smaller IMS bearing - the same one that failed at 68k miles. I'll be doing the LN Engineering IMS bearing upgrade, and then it's off to the races.

I'm actually quite pleased with this outcome - I have the latest possible engine with a serviceable IMS bearing. As much as I'd love to have a 2009 or later, I'd rather spend the money on tires and track time - and the occasional IMS bearing, every 75k miles.

USMC_DS1

This was covered by Jake Raby and Tony Callas during the Engine Build class I took last week. Of the 997.1 engines Jake rebuilt due to IMS issues most were tracked... only one was a street car.

DoninDen

Jake's claim doesn't support what we have read on this forum. I call it a mechanic's wives tale.

Petza914

Jake has explained it numerous times on this forum with lots of detail in some of the posts, touching on bearing surface speed at various rpms, self-centering of the shaft is the bearing, static load on cars with limited use, and a bunch of other points.

In a nutshell, smaller bearing works better for tracked cars and poorly for street cars. Change it to the LN bearing. Larger bearing is fine on street cars (worry about something else like bore scoring or tensioner paddle failure of you must) but won't hold up as well on track cars. Not sure what you should do if you track a larger bearing car since replacement is expensive due to the engine teardown that has to take place.

Minok

2009 - 997.2 T4 - NO failure

DoninDen

I do not believe the 997.2's have an intermediate shaft

mootsvamootsrsl

997.1 GT3, no failure

Fahrer

The engine in your car does not have a ball bearing on the IMS. It has a sliding bearing.

jbachman2

2007 997.1 @ 46,500 miles - No Failure