IMS failure plagues vehicle owners of certain Porsche models. Before buying a Porsche, you may not have been completely familiar with the term IMS. You likely have heard the term by now in the various internet forums that discuss IMS failure and repairs. However, many of those sources tend to spread contradictory information that can be hard to follow.
First, it is important to know if you own a Porsche model that is prone to IMS failure, but beyond that, it can help to understand why the IMS system is important and reasons why it fails so often.
What Does IMS Stand For?
IMS stands for Intermediate Shaft Bearing. The intermediate shaft runs through and extends out from the front and rear of the engine. The bearing helps to support the intermediate shaft whose purpose is to indirectly use the mechanical rotation of the crankshaft to drive the camshafts. The implementation of an IMS system helps to elongate the life of the chains by reducing their speed.
Why the Bearing Fails
The problem that arises with Porsche owners and the intermediate shaft pertains specifically to the IMS bearing. This bearing has become prone to failure due to a number of different factors. However, the most common cause of IMS bearing failure is generally a lack of lubrication. The bearings are submerged in oil during normal operation, or they are partially submerged with splashes of oil. Often, the bearing seal will become compromised, allowing dirty engine oil into the lubrication process. This, combined with extended intervals between oil changes, results in excessive wear on the ball joint of the bearing, eventually leading to failure.
That being said, some Porsche models have been seen to fail early on in the life of the vehicle, and long before they should have the amount of wear to justify failing. This is simply boiled down to a manufacturing error and/or poor design of the bearing and seal.
Porsche Models Prone to IMS Failure
Although not all Porsche models will fail at the same rate, the Porsche models most susceptible to IMS bearing failure in include all 986 Boxster models, 987 Cayman, and Boxster models (up to engine number 61504715), 996 models (excluding GT and Turbo), and 997 3.6ltr M96/05 (up to engine number 6950745).
Porsche cars in the 2006-2008 model years were manufactured with an unserviceable bearing type. These model years require specific bearing maintenance. It is recommended to consult a trusted Porsche mechanic for advice on how to maintain the bearing properly.
What Happens When the IMS Bearing Fails
Avoiding IMS bearing failure is recommended through preventative maintenance and consultation with an expert. If the bearing is allowed to fail, then the cam timing will be thrown off, which causes the valve piston to contract. In other words, you can expect catastrophic engine failure if the IMS bearing is compromised and eventually fails. In the event of an IMS bearing failure, the engine itself will either need to be replaced or rebuilt. In very few cases, the intermediate shaft is the only thing that needs replacement.
If you are unsure if your Porsche is likely to experience IMS bearing failure, there are a few warning signs to be aware of to avoid complete engine failure. You may find metallic debris in the oil filter during an oil change, there may be an oil leak at the rear of the engine, or you hear a distinct metallic knocking sound coming from the rear of the engine.
Once any of those signs arise in your Porsche, it is imperative to the health of your vehicle’s engine to seek out a Porsche expert and mechanic immediately. If you choose to wait, you will likely end up replacing your engine and lowering the value of your vehicle.
Trust the Experts
Whether you already own a Porsche or are looking to purchase one in the future, it is important to understand the parameters surrounding possible IMS bearing failure. Knowing if your Porsche model is prone to failure or knowing if the model you want to buy has had an IMS rebuild in the past are important parts of being a Porsche owner. To ensure the health of your IMS and your vehicle’s engine, ongoing maintenance and vehicle checks are recommended. Be in touch with a Porsche specialist that you can trust with any and all of your mechanical questions. If you live in or around the Berkeley, Emeryville, Piedmont, Oakland, CA area, then consider Germany’s Best Inc., your local trusted Porsche specialists.
* Porsche 987 Boxster image credit goes to: DarthArt.