The IMS bearing is a sealed bearing unit connected to the intermediate shaft. Both M96 (1997-2005) and M97 (2006-2008) engines are unfortunately notorious for IMS bearing failure. When failure occurs, catastrophic engine damage quickly ensues. The owner’s only recourse at this point is a costly complete engine rebuild.
The M96 engines thankfully have two options available to help prevent IMS bearing failure. The first option is to install the LN Engineering IMS Bearing Retrofit Kit. The original IMS bearing is extracted from the engine and replaced with a ceramic hybrid ball-bearing. This ceramic ball bearing does not have a seal, and is therefore exposed to the engine oil for lubrication as a means to reduce friction and keep temperatures down. The ceramic ball bearings also have a longer service life than conventional steel ball-bearings (up to five times longer). While the retrofit kit is not a permanent solution (LN Engineering recommends replacing their bearings every 4 years or 50,000 miles), it can greatly extend the life of the IMS bearing.
The second option for the M96 engine is the IMS Solution, also offered by LN Engineering. The IMS Solution is a permanent answer to the problematic original IMS bearing. It replaces the factory sealed ball-bearing with a pressure-fed oil lubricated plain bearing. The Solution essentially is a backdate to the aircooled Porsche IMS bearings, which were designed so well that failure was unheard of.
For more information, please check out our Technical Service Bulletin regarding IMS bearing failure and prevention.
This project involves replacing the original IMS bearing with LN Engineering’s IMS Bearing Retrofit Kit on a 2003 996 with 55,000 miles.
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Oil leak between the engine and transmission bell housing is a telltale sign of a failing IMS bearing
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When the bearing or the center stud begins to fail (before breaking), the IMS can “wobble,” flexing the flange and allowing oil to leak past the seal.
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It is very important to perform careful inspection for metal flake and debris in the oil at every oil change (that could lead to the IMS bearing already beginning to come apart). Here, we are inspecting the bottom of the oil filter housing for debris.
Please note: if there is too much debris, this could be a sign that your engine is already compromised and will need a complete rebuild.
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After inspecting the filter housing, we cut the oil filter open to check for any debris that may have been caught in the filter.
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Then, we remove the oil sump plate to further inspect for debris leading to IMS bearing failure.
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The engine with the oil sump plate removed. We look carefully at the oil pump pickup screen for debris.
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Factory engine sealant lodged in the oil pump pickup from assembly
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Early swirl pots are two piece and can separate under hard driving.
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To prevent separation, the plastic tabs are safety wired together to avoid engine failure from failed swirl pots and foamy engine oil.
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Oil sump plate cleaned and ready to be reinstalled.
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The oil pump pickup cleaned.
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Oil sump plate reinstalled
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LN spin-on oil filter adapter
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To begin the procedure, the transmission must be removed from the car.
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The dual mass flywheel is tested to see if it is within factory specifications. This one was not, so it will be replaced.
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A look at the rear main seal and IMS bearing flange.
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The air-oil separator (also a known common failure). This one was out of spec and will also be replaced.
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As you can see from the wear on the arm, the clutch release arm was making contact with the pressure plate.
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Broken ear on throw out bearing
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The throw out bearing housing was also cracked.
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The culprit: a broken ball socket bushing allowed excessive play in the clutch fork release arm, in turn causing the release arm to come into contact with the pressure plate. The force from the pressure plate is what caused the throw out bearing to break.
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The plastic cap on the ball socket wore over time and was able to move back. This allowed the excessive play in the clutch release arm.
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The IMS bearing flange must be cleaned before removal to prevent dirt and debris from entering the engine.
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The IMS bearing flange
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The engine must be at TDC (Top Dead Center cylinder 1) and the crankshaft must be locked.
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Bank 1 camshafts must be locked in place.
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Next, bank 2 camshafts must be locked (this ensures that the engine stays on TDC).
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Lock in camshaft
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Remove bank 1 chain tensioner
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Remove IMS chain tensioner
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Remove IMS bearing flange.
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The IMS bearing
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Remove IMS snap ring
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Remove IMS bearing
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IMS bearing removed
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The original IMS bearing, flange and snap ring removed from the engine.
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We then take apart the IMS bearing and carefully inspect the ball bearings and races to confirm that the bearing did not come apart enough to compromise the engine. This will ensure that the engine has not been affected and that the new IMS bearing will not be damaged by old bearing debris that could be left behind from a badly worn bearing.
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After confirming the engine has not been compromised and that it is a good candidate for a new bearing, we then continue with the procedure by cleaning the intermediate shaft bearing seating surface before installation of the new LN Engineering IMS bearing.
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Install the LN Engineering Retrofit bearing.
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The LN Engineering bearing flange with new three-ribbed seal.
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New crank seal installed using factory tool
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A new IMS chain tensioner is installed. This tensioner is replaced with the IMS bearing due to IMS bearing debris getting caught in the tensioner, allowing it to bleed down, lose pressure and potentially cause engine failure.
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New cam plugs are installed
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New dual mass flywheel is installed and torqued to factory specifications.
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New clutch disc and pressure plate also installed and torqued to factory specifications. As you can see from the upper right corner, the new air-oil separator was also installed. From this point, the transmission was reinstalled, oil pressure was built and the engine was started. Preventative maintenance is extremely important to the reliability and longevity of your vehicle. We recommend coming back every 80-100 miles to perform another oil change to ensure that all remaining debris has been filtered and removed. Once we have determined that all remaining debris has been removed, the recommended 1 year or 3,000 mile oil change intervals can resume.
