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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:
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.
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
Despite the fact that the 9Products IMS Bearing is superior to other bearing assemblies, it has a much more affordable price. It comes with a 40,000 kilometer limited guarantee. The engine can't be abused and all maintenance must be performed for the guarantee to be honored. 9Products has sold thousands of these assemblies over the years without one failure. Some of the 9Products re-sellers call it the "permanent fix" to the IMS Bearing problem. When you weigh all the factors it's easy to see why you should buy the 9Products IMS Bearing