Recently purchased a MY99 C2 996, first Porsche. I have read through A good deal about the 996's prior (and after) purchase and put my car into the shop for a heavy bit of preventative maintenance. All fluids flushed and replaced, aos, thermostat, water pump, brakes, bushings, drop links, tires, rms, spark plugs, clutch (sacks preformance), flywheel, plus a few upgrades: ipd, b&m ssk, 200 cell cats, and the IMSB.

I ordered the LN dual row IMSB and thought I would be good to go, but when I pulled the old IMSB out it was a single row... Also, it appeared to have been replaced previously (according to my mechanic, a former 996 owner and he has done several IMS jobs).

I quickly called ln engineering to verify I have the correct bearing and they told me that my car most likely came from the factory with a dual row and it may have had a IMS failure and was replaced by Porsche with a 3.4l with a single row IMSB.

Does this sound right to you? Either way, I love the car and overnighted a single row IMSB to put in the car tomorrow.

The only other question is how do I know if my engine is a 3.4 or 3.6? I know it's unlikely, but curious to know how to determine a 3.4 vs 3.6.

Thanks

 

If it's got a single-row bearing, the theory that it's got a replacement motor seems sound.

Get the engine number (it's on the edge of the sump plate) - you can use it to determine if the engine is a replacement.

 

Not all engines were replaced because of a failed IMS bearing. So the infor you got is partially true.

 

Check the timing chain side of the cam cover, if it says "Variocam F1", that's a 3.4.
3.6 has Variocam Plus.

 

Thank you for the info.

 

If you have "AT" in the engine number on the bottom of the case, it's a factory re-manufactured engine.

 

I had a similar surprise, and my engine number confirmed that it was a replacement engine.

It is unlikely to be a 3.6 because of the many differences in the DME and sensors.

 

Let us know what you find out! i.e. - don't leave the tread hangin'

 

Confirmed its a 3.4 (says F1 on the side of the engine); I still need to verify (AT) for factory remanufactured. The car is back on the road today, drives well and now I'm sleeping better with the imsb replaced...

Thanks to all for your input.