Porsches are susceptible to intermediate shaft bearing failure due to a couple of factors. The InterMediate Shaft (IMS) is a geared shaft that passes through the engine and extends out the front and back. Its job is to leverage the mechanical rotation of the engine's crankshaft to drive the camshafts on either side of the engine via those gears.
IMS bearing failure disturbs cam timing, forcing pistons and valves to clash, resulting in shattered valves, smashed pistons, and other engine damage in the worst-case scenario. Before fully delving into the causes of this problem, let's highlight some early warning signs that show that your Porsche's IMS bearing is nearing its demise.
Possible early warning signs
● An oil leak coming from the engine's rear parts
● During an oil change, you discover metallic particles in the oil filter
● In the later stages of failure, a minor bearing rumble or vibration may be heard
We've also discovered that lower mileage cars, cars with Tiptronic transmissions that are driven at lower RPMs had the greatest breakdowns. This is not to argue that high-mileage vehicles or manual transmissions are immune to the problem, but it's a pattern we've found over time.
Causes of IMS Bearing Failure
Ball Bearing Failure
The problem is most likely not caused by the shaft in and of itself, the problem arises as a result of the shaft's ball bearing failing. As there was no way to oil a plain bearing from the inside, Porsche utilized a ball bearing.
The intermediate shaft's other end employs a plain bearing with no thrust control. In 2006, the part's design was altered, rendering it unusable. Hence, a ball bearing was used. This was problematic since preventative maintenance was not possible.
Wear
Normal daily wear is one of the most common causes, although it is not the only one. Other problems, such as high load and lack of lubrication, are frequently blamed for premature wear. These elements will weaken the bearing over time and cause it to fail. The most typical reason for IMS bearing failure is a combination of excessive load pressure on the standard roller bearing OEM part and a lack of oil.
Furthermore, over the IMS bearing's service life, causes such as spalling, in which the bearing's surface weakens and fractures, might develop.
Overheating
Overheating occurs when a high load is combined with a lack of lubrication. Friction and fracturing are caused by the overheated metal in the bearing, which leaves pits behind. These pits exponentially accelerate the wear and tear cycle, causing IMS bearing failure prematurely.
Mileage
The failure rate of some of the original bearings is believed to be as high as 10% after only 90,000 miles on average. Because some IMS bearings have failed after only 3,000 miles, while others have lasted for 200,000 miles or more, the bottom line is that all M96 and some M97 engines in Porsche 911s(996 or 997) and Boxsters(986/987) from 1997 to 2008 are at risk of IMS bearing failure at any time, regardless of mileage.
Your Best Bet
When an intermediate shaft bearing fails, your options become limited and expensive. Even if only the intermediate shaft and bearings need to be changed (which is the most unlikely scenario), this still necessitates engine removal, examination, and disassembly. The majority of the time, your only options are to rebuild or replace the engine, both of which are very expensive.
Trust M Service to Properly Repair and Service Your Porsche
With a commitment to quality and cheerful customer service at M Service in Walnut Creek, CA, we treat your car as if it were our own. As a result, M Service has established itself as a leader in European auto maintenance and repair. Every quarter, our mechanics attend the most recent training to ensure that your car receives the most up-to-date and precise maintenance available. We understand what your car needs to keep functioning at the high level you expect.
Our mechanics work tirelessly with you to keep your car on schedule with all maintenance so you can continue to enjoy it the way it was meant to be, backed by our 24-month and 24,000-mile warranty on all services and repairs with over 70 years of combined experience. We are located in Walnut Creek, CA and proudly serve the surrounding communities. You can visit or call in to schedule an appointment with us.
* Porsche 911 image credit goes to: photosvit.