This past week we had a Porsche Cayman GT4 in for track prep. The Porsche Cayman GT4 is going to be attending the Carolinas Region PCA HPDE event we are hosting at CMP in Kershaw, SC. Below we will highlight a few points that should be inspected anytime before a Cayman GT4 hits the track. If you have any questions or concerns, please comment below or email us! Read more →
If you have researched Porsche models ranging from 1998-2008, it is more then likely you have come across an article or two related to Porsche IMS bearing failure. The purpose of this article is to explain what the Porsche IMS bearing is and what causes the Porsche IMS bearing failure. Any Porsche model using the M96 or M97 engine will have this bearing. This article should cover everything you need to know and how to resolve any issues related to the IMS bearing.
What is the Porsche IMS Bearing?
IMS stands for “intermediate shaft bearing” which is what supports the intermediate shaft on the flywheel side of the engine. Now I’m sure you are asking, “what does this mean to me as a owner or possible owner?” The shaft is utilized to run the timing chain instead of running directly off the crankshaft, which slows down the speed of timing chain rotation. Ultimately, this is better for chain life but allows the possibility of any Porsche engine utilizing this design to have an IMS bearing failure
Porsche IMS Bearing Failure
Which engines have the IMS bearing?
All Porsche models with the M96/M97 engines have the IMS bearing. Essentially, this means any model 911, Cayman, or Boxster from 1998-2008 (excluding any models equipped with a Mezger engine- GT3, GT3 RS, GT3 RS 4.0 ,GT2, GT2 RS,and 2001-2009 911 Turbo) will have this bearing. The M96/M97 engine was developed as a cost efficiency tactic for Porsche. Generally, outside of a few weak spots that do not usually occur, the M96/M97 does not usually present any major problems given that your Porsche IMS bearing doesn’t fail.
Model list featuring M96/M97 engine:
ALL 986 Boxster (1998-2004)
ALL 987.1 Boxster (2005-2008)
ALL 9871. Cayman (2005-2008)
ALL 996 911 (1998-2004 excluding ALL Turbo, GT2, and Gt3 models)
ALL 997.1 911 (2005-2008 excluding ALL Turbo, GT2, and Gt3 models)
How many Porsche IMS Bearings are there?
Porsche utilized a single row IMS bearing in the M96 engines utilized in all 986.1 and 996.1 cars. This means the 2.5L, 3.2L, and 3.4L engine in these vehicles utilized the single row bearing. It is usually more unlikely to experience a Porsche IMS bearing failure in dual row bearings but it is still possible. The 986.2 and 996.2 cars featuring the 2.7L, 3.4L, and 3.6L engine have the single row bearing which is much more likely to have an IMS bearing failure over the dual row.
Dual row bearing (left) vs Single row bearing (right)
How can I detect Porsche IMS bearing failure?
Generally, there are no early indicating signs warning of failure, without specifically checking for it. For most, it presents as an unexpected, sudden failure. Although, there are a few things to check for if your vehicle receives maintenance regularly by a workshop that is familiar with these model cars. Checking the engine oil for metal shavings every-time it is drained, cutting open the oil filter & checking for metal shavings, looking for black fragments of plastic from the bearing and a rear main seal leak can also be a sign of IMS failure. You can also use a Porsche scan tool to check for camshaft deviation to verify your Porsche IMS bearing failure is coming.
What causes the IMS bearing failure?
The IMS bearing is submerged partially in oil when the engine is not active. The bearing is a sealed bearing that does not have any pressurized oil feeding the bearing to keep the ball bearing pressurized and lubricated properly. As a by product of time, because generally the cars with low mileage or those that aren’t driven often have the rubber seal that is exposed to air causing it to harden and dry rot. Once the seal is dry rotted, it can be compromised by the engine oil washing the bearing out and allowing more then needed slop. This is due to the oil not being pressurized inside the bearing, which allows the bearing to have unnecessary play allowing the ball bearing to wear out. At this point, it is usually the strongest sign of IMS failure when it appears a rear main seal is leaking but too commonly mistaken for this because the shaft is directly underneath the crankshaft on the flywheel side of the engine therefore appearing to be a rear main seal leak.
Leaking IMS bearing pictured above
How do I prevent the Porsche IMS Bearing from failure?
*Disclosure: I am not affiliated with, nor am I paid to review LN Engineering*
Thankfully, LN Engineering has created multiple solutions to prevent your Porsche IMS bearing failure from occurring and we can also assist with installation of the bearing and other information on the bearing! LN Engineering has released a bearing that is also warrantied against defects which we can install in your Porsche engine at HBi Auto. Below is a list of solutions they offer. Feel free to message us at firstname.lastname@example.org or call us at 336.978.8818 for more on how we can help with this or assist you with any questions you may have. We also offer nationwide shipping options if you are not local to us!