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I have compiled facts about the infamous IMS Bearing from several sources such as Pelican Parts, Autohaus Hamilton and the Oregon PCA.

   The purpose of the intermediate shaft is to drive the camshafts indirectly off the crankshaft. By

using an intermediate shaft, the speed of the chains are reduced, which is better for chain life.

It is not known exactly why these bearings fail, but there are many contributing factors including

over-loading. Poor lubrication, long drain intervals, high fuel and moisture content in the engine

oil, high oil temperatures, and even operational speeds can also affect bearing life. That’s why

some bearings last 3,000 miles and others have lasted over 200,000 miles. Here is a good link

about bearing failures and some of the common causes:

http://www.maintenanceworld.com/Articles/manufacturing/bearing-failure.htm

Foreign matter:

One of the most common sources of trouble in bearings is wear and pitting caused by foreign

particles and is responsible for 70% of all early bearing failures. With six years and tens of

thousands of IMS Retrofit procedures having been carried out since 2008, we have enough

experience to confirm that foreign object debris can and will compromise the replacement IMS

bearing. We have confirmed documented failures of the [LN Engineering] IMS Retrofit bearing

after it was installed as part of a reactionary procedure when the original bearing had already

started to fail or had failed completely.

Now for some technical information from our bearing engineering team: “There are many

reasons for bearing failure, and usually each failure is due to a combination of causes, not just a

single cause. Spalling occurs as a result of normal fatigue where the bearing has reached the end

of its normal life span but this is not the most common cause of bearing failure. Spalling detected in bearings can generally be attributed to other factors. A common cause of bearing

failure is due to contamination from tiny metallic particles left over from the wearing of other engine parts. These particles are suspended in the oil and if they are allowed to get into the bearing,

the result is tiny dents in the hard steel raceway. Often the dent is surrounded by a microscopic

raised area (or ‘lip’), and when the ball rolls over this lip, the ultra-high point loading exceeds

the strength of the steel and it fractures, leaving behind a jagged depression (or ‘pit’). Once this

cycle begins, wear is greatly accelerated and the bearing will fail prematurely.” 

One thing is for sure; once you have experienced an IMS bearing failure, there is no turning

back. A complete engine disassembly is required to replace the intermediate shaft and in most

cases, complete rebuild or engine replacement is your only option.

When an IMS failure occurs, or more specifically the ball-bearing or bearing support fails, the

intermediate shaft is damaged beyond the point of being serviceable, but moreover, debris from

the failure contaminates the entire engine, requiring a complete teardown and rebuild to

recover from such a failure. In worst-case scenarios, the cam timing can also be thrown off,

causing valve to piston contact, and in some cases, even lead to a failure that requires

replacement of the engine. In that case, the engine will not be accepted as a core, requiring the

purchase of another core or to pay an ever-increasing core charge from Porsche on top of the

cost of the replacement engine. Aside from the proactive approach of replacing the IMS bearing

prior to such a failure, prevention and early detection are some of the steps that can be taken to

try to minimize the risk of a costly engine failure.  With model year 1997 through 2005 engines however, the bearing is indeed accessible. Any IMS

bearing replacement is intended to be installed as a proactive measure in preventative and

regular maintenance. Once an engine has suffered a failure, replacement of the intermediate

shaft bearing is no longer an option. Installing a replacement IMS bearing in an engine that has

already suffered a failure will result in a subsequent failure due to collateral damage, including

but not limited to debris contaminating the new bearing.

Lubrication:

Oiling is just one part of the IMS failure problem. As supplied by Porsche, the intermediate shaft

uses a sealed ball bearing. The original bearing was grease filled, considered a “permanent”

lubricant. However, the original bearings and seals used are rated only to 250F and over time,

the seals become hard, allowing the grease under normal operation to be “washed” out of the

bearing during operation.

Additionally, as the intermediate shaft itself is completely submerged at times, the shaft will

actually fill up with engine oil. With long drain intervals, contaminants in the oil find their way

into the bearings and intermediate shaft. These worn out seals do allow oil in but they also limit

the exchange of fresh oil.

Once the bearing begins to wear, the seal will actually fail completely, allowing for oil to wash

out the permanent grease but not allowing for fresh oil to exchange in and out of the bearing

during operation. It is at this point that you can begin to find debris in the filter from the seal

and from the bearing itself.

The 9Products IMS Bearing is made from CrNiMo6  the hardest steel chromoly alloy available.  Every part of it.  This helps to prevent any foreign debris in the oil  from causing pitting to start which is the first and most common beginning to the failure of the bearing.   The 9Products IMS Bearing can be used on both single and double bearing assemblies.  The 9Products  single, extra strong row of bearings is stronger than any of the Porsche 2 row assemblies.  Very little oil is needed to keep the 9Products bearings working flawlessly. The bearings are sealed and use a proprietary blend of permanent lubricants  It also has a much better oil seal that does not get hard from heat and stress and keeps the oil from leaking out.  In over 8  years of sales there has not been one failure of the 9Products IMS Bearing