A friend is contemplating buying a 996 and asked me about the IMS failure issue. I told him the little that I knew, then looked into it a little (very little). I'm told that it was a seal dual bearing and now it is a sealed single bearing. Further, I was told by a dealer service manager that it's not just the bearing below the rear seal that's the problem. I can't personally see how a sealed bearing could be in an engine for decades without failure. I'm hoping someone on this forum is familiar with the situation to enlighten me on:
1. Exactly what caused this issue
2. How are things different now than in the 996?

ChuckJ

 

No IMS in engine since 2009.

 

Beautiful! Thanks, Steve

ChuckJ

 

For those with 996's that want to be safe there is a kit to replace the IMS. Apparantly only 1/2 of 1% of the engines of the 996 and 986 have had the problem. Risk is, if it goes the engine is gone.

 

Do you know how much the kit is installed and is it a complete solution. I'm told it is $23,000 for the engine replacement.

ChuckJ

 

I had this done to my previous 996, the kit is only about $600 but the labor is much higher. It is usually recommended to do it during a clutch replacement (if a manual) since most of the labor is the same. For an automatic it would be similar labor as replacing the flex plate I believe.

David

 

Is that the problem, the engine flexes and puts load on the double bearing? Is there a condition that causes the flex?

Chuck

 

I've been advised that the problem was with the manufacturer of the part having produced a bunch of bad bearings. Also been told that Porsche actually knows the engine serial numbers of every car with the suspect bearing but won't release the info.

 

Apparently one end of the Intermediate Shaft is in engine oil, but not the other. This is true on the M96 and 97 engines (so not Turbos or GTs from this era). The other end is set in a sealed ball bearing unit. The seal apparently breaks, loses the packed lubrication, and the bearings go bad. If the IMS bearing goes, there goes your timing chain and the entire engine. At some point in 2005 they updated to a hardier bearing, and in 2009 took it out altogether. I've not heard much about problems in the 05-09 range, mostly older.

I see several different solutions now advertised in Excellence magazine. "IMS Direct Oil" and others. The longest and best known is the L&N ceramic bearing kit. One can retrofit these into anything up to the 05-09 (apparently you can't get to the bigger IMS bearing, so while the later years are more robust, you can be proactive on older ones).

Engines can fail for several reasons, not just this, so it's not worth losing too much sleep over. Check out the L&N Engineering site, who have recommendations on this, from their refit, a direct feed oil "permanent solution", to changing oil frequently, watching for metal shavings at oil change, etc (they sell a magnetic oil drain plug to help with this). I've not looked into the other options now emerging.

All in all, something to be aware of in that era car, but not necessarily something to worry too much about. Best advice seems to be replace the bearing with an upgraded unit when the clutch is done.

 

There is also a class action settlement from Porsche on this for the older models... You might want to check the 996 forum for details.