Porsche 986/996 IMS bearing: what it is, the risk, and real retrofit prices

The intermediate shaft bearing on M96 Boxster and 911 engines can fail without warning. What the retrofit involves, why quotes vary so much, and what owners paid.

Ask anybody shopping for a 986 Boxster or a 996 911 what scares them, and it's three letters: IMS.

The intermediate shaft runs inside the M96 engine and drives the cams through the timing chains. It's supported by a sealed bearing at one end. When that bearing fails, the shaft wobbles, the timing goes, and the engine is usually done. Some owners never have a problem. Some do. The single-row bearing used on many of the later cars has the worst reputation.

Is there any warning?

Sometimes. Metal flakes in the oil filter are the classic early sign, which is why a lot of owners cut open the filter at every oil change. A rattle from the back of the engine can show up late. Often there's no warning at all.

What the retrofit involves

The transmission and clutch have to come out to get to the IMS cover. Then the old bearing is pulled and replaced with an upgraded one (LN Engineering's retrofit is the one you'll see named most), or with the more permanent IMS Solution which changes the bearing type entirely.

Since the transmission is already out, almost everybody does:

• Clutch, pressure plate and often the flywheel
• Rear main seal (RMS), which these engines also like to leak
• Sometimes the air-oil separator (AOS) and other small stuff

Why our prices go from $1,500 to $6,000

Look at the details on the cost page. The $1,500 report was a labor quote for IMS and RMS on a Tiptronic car (no clutch). The higher ones include the IMS Solution, a clutch, flywheel, AOS and more. It's really several jobs bundled together, and the bundle is what you're pricing.

Ask before you book

1. Which bearing or kit, and is it the newer style?
2. Did they confirm your engine's bearing can be serviced this way? Some of the last M97 engines used a larger bearing that can't be swapped without a teardown.
3. What's included besides the bearing?
4. Are they experienced with this exact job? Ask how many they've done.