The intermediate shaft bearing, commonly known as an IMS bearing, has a significant failure rate in the Porsche 911 and Porsche Boxster from model years 1997 to 2005. Its structure and design cause the bearing to break early, which causes a catastrophic engine failure.
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You’ll have a bad time if your IMS bearing fails.
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.
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.
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.
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.
How to Determine If Your Porsche’s IMS Bearing Is Failing
IMS bearing failure is a problem that affects Porsche vehicles quite frequently. The intermediate shaft, which runs the length of the engine, is supported by the IMS bearing (also known as the intermediate shaft bearing). In most Porsches, the issue is not the actual intermediate shaft. The infamous engine issues that beset this antique automobile brand are caused by the IMS bearing.
The IMS bearing in your Porsche could break down from regular wear and tear. However, mechanical errors account for the majority of this feature’s failures. Due to their older designs, the Porsche models 986, 987, 996, and 997 are more vulnerable to IMS bearing failure.
Lack of lubrication causes the bearing to repeatedly overheat, which eventually leads to IMS bearing failure. The only real defense against this is to get your automobile serviced on a regular basis by qualified mechanics and to get an oil change every two years.
IMS bearing failure may not be completely preventable, but any mechanic with expertise in Porsches will be able to spot any little details that might point to this system malfunctioning. To avoid a complete failure, they will give you advice and make improvements while conducting inspections.
What does a Porsche’s IMS service entail?
If you had read the phrases “premature catastrophic engine failure” above, you would have wondered how a very small component could have the potential to instantly and seemingly without warning destroy an entire engine. We’ll briefly discuss what an IMS bearing is and how it works without getting too technical.
IMS stands for intermediate shaft, to start. The intermediate shaft, which goes through and exits from the front and back of the engine, is essentially a geared shaft. The purpose of the intermediate shaft is to employ those gears to indirectly drive the camshafts on either side of the engine by using the mechanical rotation of the engine’s crankshaft. But the 996 and 997 IMS-related “engine troubles” that are now well-known and notorious are not caused by the intermediate shaft itself. The then-radical and novel water-cooled “M96” engine created for the 996 was by no means a fresh development in terms of basic design or usage of an intermediate shaft. The horizontally opposed (sometimes known as a “boxer” arrangement) flat-six engines that are so famous for the Porsche 911 have really had an intermediate shaft for as long as the 911 has existed. The use of an intermediate shaft on Porsche’s flat-six engines had been well-proven up to this point in the long history of the 911’s development, both conceptually and practically. The problem (pun intended) with the introduction of the M96 and the initial production runs of the subsequently upgraded “M97” engines lies in the sealed cartridge-style ball bearings, sometimes known as the “IMS bearings,” that support the IMS.
Which year of the Boxster has IMS issues?
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