Two glaring flaws in the factory-original IMS bearings can be blamed for their primary weaknesses: (1) The ball bearings’ construction doesn’t quite make them strong enough to endure the mechanical and thermal demands placed on them, and (2) Inadequate lubrication of the bearings.
Some IMS bearings have been verified to have failed after only 3,000 km.
IMS bearing failure may be caused by a variety of contributing factors, and frequently, a combination of causes leads to bearing failure. It is difficult to determine with any degree of precision the precise rate of failure of these IMS bearings. Reliable sources have reported that the failure-rate of some of these original bearings has been estimated to be as high as an astonishing 10% after an average of just 90,000 miles. However, claims of which, especially those made by unqualified “experts” or ones found in the numerous forum threads about this topic, can vary drastically. The only safe conclusion that can be made is that all M96 and some M97 engines in Porsche 911s (996 or 997) and all Boxsters (986/987) from 1997 through 2008 are susceptible to IMS bearing failure at any time, regardless of mileage, as it has also been verified that some IMS bearings have failed after only 3,000 miles, while others have still lasted for 200,000 miles or more.
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Which Porsche models are susceptible to IMS bearing failure?
All Boxster, Cayman, and 911 vehicles from MY1997 to MY2008, with the exception of Turbo, GT2, and GT3 variants, are susceptible to IMS bearing failure.
But over time, the types of bearings utilized changed, and some of them were more likely to fail than others. According to statistics, the Boxster 986 and 911 models built between model years 2000 and 2005 are the most likely to experience IMS bearing failure, whereas the odds are extremely low for a Boxster 987 or Cayman built after a stronger bearing was introduced in late 2005.
In terms of mileage, there is no clear trend in the failures; some owners were unfortunate enough to encounter IMS issues at less than 20,000 miles, while others assumed they were safe only to have the bearing fail at 130,000 miles. In summary, you should be aware of potential issues if you now own or intend to purchase one of the versions with the weaker bearing that were in use from 2000 until late 2005.
The base engine (3.6) bears the designation “M96,” and depending on your engine number, you may have the smaller IMS or the revised bigger bearing:
Engine (3.6) number M96/05 69507476 has the larger updated IMS bearing, while Engine (3.6) number M96/05 69507475 has the smaller IMS bearing.
The “S” Engine (3.8) is designated “M97” and features a choice of a smaller or bigger upgraded IMS bearing:
Engine (3.8) numbers beginning with M97/01 68509791 have the larger updated IMS bearing, whereas Engine (3.8) numbers up to M97/01 68509790 have the previous IMS bearing.
Ultimate Guide and Frequently Asked Questions for Porsche IMS Bearings
The IMS (middle shaft) of an M96 or M97 engine is supported by a sealed ball bearing. the bearing installed on the intermediate shaft by
Porsche offers an interval, replacement process, or replacement IMS bearing for
It was not able to replace or upgrade the original factory IMS bearing until LN Engineering.
inquiries to find out all there is to know about intermediate shaft bearings
and why the best IMS bearing Retrofit and Solution products are those made by LN Engineering
Does the 996 911 suffer from the Porsche IMS bearing?
Furthermore, according to Rennlist and Pelican Parts forum users, owners of 996 Turbo, GT2 or GT3 models are exempt from Porsche IMS bearing problems. The so-called “Mezger engine” was indeed utilized in these, but it had a modified design that fixed the IMS fault.
The later 997’s IMS problems were also resolved by switching to the Mezger engine, which bears the name of one of Porsche’s illustrious engineers, Hans Mezger. According to Revolution Porsche Specialists, the earlier (2005–2008) 997.1 vehicles still had IMS bearing problems. The company asserts that Porsche 911s manufactured between 2000 and 2005 are the ones that experience IMS bearing failures the most commonly. However, a new engine design for the 2009 997.2 Porsche 911 eliminated the problematic IMS bearing. Any Porsche 911 made in 2009 or after is therefore protected from IMS bearing failure.
Fortunately, even though the IMS problem had an impact on resale values, Porsche 911 sales weren’t greatly harmed. A 996 or 997.1 911 can be an incredibly economical entry into Porsche ownership as long as you keep that in mind.
Prevention and upkeep
Unfortunately, your IMS bearing does not always fail with a warning. Taking your car in for maintenance and getting a professional oil change with an inspection are the finest preventative steps you can implement.
Long before symptoms emerge that are obvious to a driver, a Porsche expert will spot signs that your IMS bearing is beginning to degenerate. This is why you need to continue with your routine maintenance.
The only real way to prevent IMS bearing failure, which affects all Porsche 986, 987, 996, and 997 models, is to make sure that your car is regularly serviced and inspected. Better yet, have your IMS replaced with a more recent model that won’t be as problematic.
Paul Kramer’s The Truth About the IMS Bearing
Not to pick on, but the 2009 model year marks a change in that Porsche fully did away with the IMS bearing. Although the IMS bearing was not completely abolished by the 2006-20008 (with the exception of a few very early model years that still had the leftover M96 engine), the failure of the bearing was essentially eradicated. I sincerely doubt that I have read about a single instance of an IMS failure on an M97 motor. It’s interesting to note that IMS bearings have been used in Porsche engines since the 996s. Every 911 from 1964 to 2008 had an IMS bearing, in actuality. Even the cherished Mezger automobiles, such as the Turbos and GT3s, lacked IMS bearings. They simply never fell short. The M96 motors’ failure was mostly the result of poor upkeep. It’s true that poorly designed seals permitted bearing failure in vehicles with little mileage and irregular oil changes. I have never saw an IMS bearing fail in a vehicle that was frequently driven and received regular/appropriate oil maintenance (at least once a year).
With Dwain Dement (the owner of Vision Motorsports), I had a lengthy conversation on the M97, M96, and 2009 direct injection motors. I even went on a tour of his engine manufacturing facility. Each year, Dwain produces around 100 M96 engines as well as almost as many M97 race motors. The IMS bearing is a genuinely trivial problem, which is funny. Any wear issues can be easily detected WELL before catastrophic failure with the right maintenance, etc. However, the majority of individuals simply follow the lore that is widespread online. The casting of the cylinders into the casing is the major problem with M96 motors that is frequently disregarded. They may crack with prolonged use or high mileage. Since their cases are thicker, M97 motors rarely experience cracking problems. According to Dwain, he has never witnessed an M97 motor’s IMS bearing fail. He claimed that the bearing is considerably bigger and stronger.
The M97 IMS failure rate is interestingly close to zero…even with rather subpar care. Additionally, due to how much larger the bearing is than its predecessor, it cannot be replaced until the engine case is opened. Since they are better for higher RPM and a little more durable than direct injection motors in terms of boring to bigger displacement, etc., Dwain employs the M97 motor for the majority of his race car engines. After each race, he conducts an oil study on every M97 engine he supports (well over 20-cars). It’s interesting to note that he rarely observes excessive metal wear until there has been a serious missed shift, which he notes using the Motec(r) system, which is far more accurate than the original DME.
Sorry for the rant, but I’ve written numerous articles about it, visited four engine shops, and spoken with a ton of mechanics and engine builders, including Dwain, Deiter (Andial), Tony Callas, and others. There are numerous misconceptions regarding IMS bearings, etc. I went directly to folks who see these motors and bearings on a daily basis rather than depending on what is written online or in magazines.
Personally, I believe that direct injection motors are given far too much credit. Think about all the troubles that VW and BMW are experiencing with that configuration. All day long, I would choose an M97 engine to save money.
Porsche used a dual row intermediate shaft bearing from 1997 to 1999, and this bearing has proven to be just as durable as the larger single row used from model years 2006 through 2008. According to the IMS Class Action Lawsuit brought against Porsche, the Dual Row produced in-house was far more robust than the Single Row utilized from 2000 to 2005.
Porsche started phase-out of the dual row bearing in 2000 and switched to a smaller single row bearing with a much lower load capability. All engines used this smaller intermediate shaft bearing from 2002 through 2005, but for the 2006 model year, they switched to the larger third revision, which restored the load capacity to that of the original dual row bearing. The larger bearing for model years 2006 and later also had a larger diameter, which improved the bearing by increasing the bearing and ball speed. The IMS failure concerns have not entirely been resolved despite this adjustment, though.
What year did Porsche address the IMS issue?
Following the release of the IMS Retrofit by LN Engineering in 2008, Porsche introduced their own IMS bearing replacement in 2017 using a sealed ceramic hybrid ball bearing.
Do Porsche Boxsters have problems with IMS bearings?
With the exception of the Turbo, GT2 and GT3 models, which continued to employ the air-cooled type shaft, all water-cooled 911s, Boxsters, and Caymans from 1997 through 2008 are susceptible to IMS bearing failure.
Porsche modified the bearing type numerous times during the production of these vehicles, first with a dual row bearing from 1997 to 2000 (with minor failure), then switching to a single row bearing from 2001 to 2005. (reports indicate this single row bearing as being the most liable to failure). A larger single row bearing with increased load capabilities was utilized in the following 997 and 987 Boxster and Cayman models, and it turned out to be much more reliable. View the Costs of Replacing IMS Bearings