Porsche IMS Bearing Issue Explained
The intermediate shaft (IMS) bearing is a hot topic among Porsche owners, and you’ve probably heard of the infamous failure occurring on various early 2000s models. It’s become one of the major worries of 996 911 owners, but is this concern warranted?
In this article, we’ll cover what the IMS bearing is, its history of failure on Porsches, and the current state of this issue in 2024.
What is The IMS Bearing?
The intermediate shaft’s responsibility is to indirectly drive the camshafts from the crankshaft. By doing this, the speed of the chain is reduced and in turn, provides superior durability. The intermediate shaft is also used to drive the oil pump.
The IMS bearing is what is used to support the intermediate shaft on the flywheel side of the engine. It’s critical for maintaining smooth rotation and minimizing vibrations.
What is IMS Bearing Failure?
With the bearing playing such an important role in the operation of the motor, you can imagine that even the smallest issues can cause major problems in the internals of your engine.
Over time, the rubber gaskets of the bearing can begin to fail, allowing the grease trapped in the bearing to leak out and reducing lubrication. The lack of lubrication in the spinning bearing will result in overheating and the subsequent fracture of the metal bearing itself.
With this fracture, the wear of the bearing will only be accelerated. In a severe failure, the timing of the engine will be thrown off which can cause the valve to collide with the pistons. In the vast majority of cases, IMS bearing failure will eventually lead to irreparable engine damage.
After the bearing has failed, there’s no easy fix and the engine will need to be torn down for IMS bearing replacement and inspection/repair of further damage.
What Porsches Experience IMS Bearing Failure?
While many Porsche engines employed an IMS and bearing over the years, the infamously problematic bearing is only present on a select range of model years.
From 1997-2008, Porsche’s flagship 911 and entry-level Boxster models both experienced widespread IMS bearing failure at higher mileage.
These issues cover the entirety of the 996 911 and 986 Boxster generations, which spanned 1997-2005. With the introduction of the 997 and 987 generations in 2006, Porsche introduced a larger non-serviceable IMS bearing to their updated motors. IMS failure is less of a concern in these model years but still has the potential to develop the problem.
This larger bearing is also present on 2006-2008 Cayman models, meaning they also may experience failure at high mileage.
Following the 2008 model year, Porsche redesigned their motors for the new generation without an intermediate shaft, which instead drives the camshaft directly off of the crankshaft rather than from the IMS.
Warning Signs of IMS Failure
While it may be already too late in some cases, there are some warning signs of IMS bearing failure that you should watch for as a Porsche owner. If you can catch it early enough and address it ASAP, you may save yourself the pain of a complete engine rebuild or replacement.
If you hear a rattling, banging, or knocking sound from your engine bay, you should have your vehicle inspected immediately as it may be the result of early IMS failure. A loud popping sound from the same area could mean a complete failure, and you should turn off your vehicle immediately to avoid further damage.
Another potential sign of failure is the presence of metallic flakes in your oil or filter. Though this can be the result of other causes, metal in your oil should be taken seriously as it often points to a critical issue within your engine.
How to Avoid IMS Failure
The tried-and-true method to mitigating the potential for IMS bearing failure is a preventive replacement with an upgraded bearing. Almost all OEM bearings from the ‘97-’05 era are bound to fail at some point, whether that be at 10,000 miles or 200,000. Aftermarket options with higher load capacity will prevent the initial leaks and fractures that cause harmful timing issues.
Do I Need An IMS Replacement?
If you own, or are looking to own, a Porsche from this era you may be concerned about the condition of your bearing (and rightfully so). But, how do you know if a preventative replacement is needed on your vehicle?
The answer to that question lies in the current IMS bearing sitting in your vehicle. If it’s the original OEM part, you should have it replaced with a stronger aftermarket option to avoid unexpected failure.
However, many if not the majority of affected Porsche models have already had the service performed at some point. With the upgraded bearing, the chance for failure is considerably reduced and the vehicle most likely does not need a replacement.
If you’re looking to purchase a used Porsche from these years, you should confirm with the previous owner or dealer whether the service has already been completed or not.
Porsche Services in Ann Arbor
If you’re looking for an inspection or bearing replacement on your Porsche, the experienced Porsche specialists at Orion Automotive in Ann Arbor have the equipment and specific training necessary to provide your vehicle with the utmost level of care and precision.
Give us a call or schedule online to secure an appointment and chat with our friendly and knowledgeable team on a personalized service plan for your Porsche vehicle!
