Background

Porsche’s engines had intermediate shafts for decades prior to the M96 engine, and they never posed a problem. For the M96 engine, Porsche decided to use a grease-fed roller bearing for the IMS with “lifetime” seals. Unfortunately, these “lifetime” seals tend to leak, allowing the grease to escape but not allowing engine oil in. The bearing loses lubrication and fails, usually causing the engine to go out of time, which results in catastrophic engine damage.

Replacement of the bearing requires removal of the transmission. As such, it is generally recommended to do it at the same time as a clutch replacement, and to also replace the rear main seal at the same time.

IMS Bearing Types

• Dual-Row – This was the original M96 IMS bearing. It is generally considered to have low failure rates, and many people opt not to install any preventative measures as a result. However, they can still fail. These are present on all cars through MY99, and in some MY00-01 cars.
• Single-Row – In MY00, Porsche began to use single-row IMS bearings in their engines. These are considered to be the most failure-prone, as they cannot handle as much stress as the earlier dual-row bearings. Some MY00-01 vehicles have these, but it is impossible to tell simply based on engine serial number – the only way to be sure is to remove the bearing. All vehicles produced MY02-05 have single-row bearings. Single-row bearings allegedly have a failure rate between 5-8%.
• “Big Bearing” – In MY06, Porsche introduced the so-called “big bearing” on their engines. These are far less susceptible to failure than previous iterations, as they are actually located within the engine block. Failure almost always occurs only in vehicles which spend a lot of time at the track or in other high-stress situations. However, unlike previous iterations, replacement requires completely tearing apart the engine.

Solutions

These are in order from least to most effective.

• IMS Guardian – This is a magnetic chip detector that installs into the oil sump drain plug. It sounds an alert when it detects metal shavings in the oil (a common symptom of early IMS bearing failure). If you want to avoid the expense of preventative IMS bearing repair, you should install this so that you have at least some chance of saving the engine should the bearing fail.
• IMS bearing seal removal – Some people believe that simply removing the seal on the IMS bearing allows enough oil in from the engine to keep it lubricated.
• Factory bearings – Some people elect to replace the IMS bearing with a new factory one every time they perform a clutch replacement.
• Upgraded bearings – Pelican Parts and LN Engineering sell upgraded bearings which they claim are stronger than the factory bearings. These have maintenance intervals, and are generally best changed with the clutch. This is the recommended minimum course of action.
• Oil-fed bearing conversion kits – TuneRS, LN Engineering, and European Parts Solution (EPS) make kits that convert the original greased IMS bearing into an oil-fed bearing. These are considered “permanent” solutions, in that they do not treat the IMS bearing as a maintenance item to be replaced after a certain number of miles (unlike the aforementioned upgraded bearings).
  • EPS’s kit converts the IMS bearing from a roller-type to a cylindrical roller-type. Of the three, its oil feed is the simplest, with just a small hole punched between the IMS front cover and the oil pump. There are questions about its effectiveness, but EPS claims to have no failures thus far.
  • The TuneRS kit is the most straightforward of the three. It does not change the bearing itself, but simply adds an oil feed.
  • The LN Engineering kit is expensive and involves a raft of other changes to the engine, claiming to fix a number of other issues in addition to IMS bearing failure. It converts the IMS bearing from a roller-type to a plain bearing, in addition to making it oil-fed.