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.
In This Article...
What signs might indicate an IMS bearing failure?
destruction of the engine Because the Porsche original ball bearing is sealed,
Depending on the bearing, it can produce entire or no visible debris between 2000 and 2005.
before completely failing, the vehicle will continue to generate wear particles for thousands of kilometres.
That also applies to engines that have a replacement ball already installed.
or IMS roller bearings, all of which, with the exception of the IMS, are wear components.
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.
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.
What causes the breakdown of Porsche IMS bearings?
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.
The IMS bearing is where?
The technical side of the IMS and IMS bearing is shown here. Internal engine component, the Intermediate Shaft (IMS) is located just beneath the crankshaft in the M96 and M97 engines. It is supported by the front console on the front end of the engine and a roller bearing on the back end. All 4 camshafts as well as the primary oil pump are powered by the IMS, which is driven by the crankshaft using either a duplex chain or an internal tooth chain. It is driven by the crankshaft at the flywheel end of the Intermediate Shaft. The timing chain for the 1, 3 bank is also on this end (cylinder 1, 2 and 3). The timing chain for the 4, 6 bank (cylinders 4, 5, and 6) is located at the front of the engine, behind the crankshaft pulley, along with an 8mm hex key that operates the oil pump. The IMS bearing, a sealed roller bearing, supports the driven end of the IMS (back of engine) (not lubricated by engine oil). A plain bearing that is pressure-fed by the main oil pump and hasn’t demonstrated any issues supports the front end of the IMS. A steel flange that is fastened to the back of the engine block holds the IMS bearing in place. The inner race is stationary while the outer race rotates thanks to the flange holding the bearing’s internal diameter (ID). To create a clamping force between the bearing and outer flange in the IMS bearing, a center stud is used.
Should my IMS bearing be replaced?
Any IMS bearing replacement is meant to be installed as a proactive step in routine maintenance and preventative care. The replacement of the intermediate shaft bearing is no longer an option once an engine has failed.
What model year Porsche has an IMS issue?
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 build and design cause the bearing to prematurely fail, which causes a catastrophic engine failure.
How much does a Porsche 911’s IMS bearing cost to replace?
Thousands of independent technicians advocate IMS Retrofit ceramic hybrid ball bearing as the best preventive treatment because it is the only long-term fix for IMS bearing issues in M96/M97 engines. IMS Retrofit replacement bearings typically cost more than $4,000 in labor and materials, but they can be installed at the same time as the clutch. Compared to the price of rebuilding or replacing the entire engine, this is a relatively low expenditure. The cost of this repair should be weighed against the minimal likelihood that an IMS breakdown will occur in an older Porsche. You might decide it is worth the risk if you carefully evaluate the possibility of a future failure and compare it to the cost of an IMS Retrofit bearing. This preventative procedure, however, may very well be a worthwhile outlay to avoid future harm and larger spending in the future if you are worried about the health and well-being of your Porsche.