Carrera S Blog: A Chronological Account of My Ownership

November 19, 2017 

THE INFAMOUS IMS BEARING ISSUE

While Porsche has an enviable reputation for engineering excellence they seemed to have stumbled on at least one issue when they transitioned from the air-cooled engines to the water-cooled variants. The engine in the 996 (the first water-cooled model) and the 997 used an intermediate shaft to transmit motion from the engine crankshaft to the cams. One end of the shaft uses a lubricated journal-type plain bearing similar to what was used in the air-cooled engines (second image below), but at the other end a ball bearing was installed. This did not apply to the GT3 or Turbo cars.

The Porsche Club of America featuring Jake Raby of Flat Six innovations produced a very helpful video that explains the IMS issue in terms the typical Porsche owner can understand. The following information is taken from that video that may be found here: 

The image below shows the flywheel/transmission end of the engine.

M96 & M97 Porsche Engine IMS

The image below shows the end (front) of the engine opposite the flywheel/transmission.

M96/M97 Plain Bearing – Front of Engine

The failure of the ball bearing results in catastrophic consequences and the rate of failure, while relatively low, is high enough to cause grey hairs and nightmares for owners of 996 and 997.1 and 997.2 Porsches.

During the production run of the these models, three generations of intermediate shafts with different ball bearings were used. One would think that engine numbers and/or VIN numbers might tell the owner which bearing is in his/her engine; however, experts agree that the only way to know for sure which bearing is in the car is to do a visual inspection. This, of course, means dropping the transmission.

The first generation of intermediate shafts began in 1997 and ran through the middle of 2000. The shaft has a dual row chain sprocket. In mid-2000 the factory upgraded the IMS to use an internal tooth chain, a wider and quieter chain. In 2006-08 a third generation shaft was used. It was essentially the same as the second generation (very similar chain sprocket); however the diameter of the bearing housing of this shaft was a larger diameter than the second generation. This shaft was was used through 2008.

 

 

The information above relates to the three generations of Intermediate Shafts, the image below shows the three generations of Intermediate Shaft Bearings:

Three generations of IMS Bearings

So, now we know about the thee generations of intermediate shafts, and the three different types of bearings that were used from 1997-2008. We also know from the research that was conducted for the class action suit against Porsche regarding bearing failures that the cars with the #6204 smaller single row bearing are the most likely to encounter IMS bearing problems.

My 2005 Carrera S is an early model, having been manufactured in October of 2004. It is a low mileage (7,200 miles) very original car with no record of significant engine maintenance or replacement. All of this information points to my car having the bearing most likely to fail. 

Therefore, the only thing to do in my judgement is to pull the transmission, inspect the bearing flanges and then based on the confirmation of what bearing I have then choose one of three courses of action:

1. Leave things as they are but change my oil frequently, test the oil for contaminants (metal and/or plastic every time I change the oil, and pray;

2. replace the bearing with an upgraded ceramic ball bearing; or,

3. replace the bearing with the “IMS Solution” developed by Jake Raby and Charles Navarro. The “Solution” replaces the ball bearing with a plain bearing and provides for a oil feed to the bearing. The ceramic bearing and the “IMS Solution” are sold by LN Engineering.

What will we look for when the transmission is removed and the engine can be visually inspected? (Three images to add)

More to come:

 

 

November 18, 2017 

CLEAN-UP & INSPECTION

Saturday, November 18 was “clean up” day for the Carrera! It smelled a little musty (not damp, just closed up) from being stored. Apparently, that is how it had spent most of its life since 2007, as that was the last sticker on the Connecticut license plate.

I first vacuumed everything then I shampooed the carpets and the mats (which were in excellent condition), used Lexol leather treatment on the leather seats, wiped down all of the surfaces with Griot’s Garage interior cleaner, and cleaned the glass inside and out.

I inspected the new Pirelli tires and made an appointment to have them installed at Mid-Atlantic Motorwerks on Monday November, 27. The front tires are 235/35ZR19.

Front Tires

And, the rear tires are 295/30ZR19XL

Rear Tires

I then did a little photo shoot of the car. At this point the Porsche had not been inspected and with no windshield sticker I am hesitant to take her out on the road. Of course, the drive will be the true test, but I must say that I am extremely impressed by the condition of the car. This is one time where a car purchase actually exceeded expectations!

I then did a little photo shoot of my new (to me) 997.1.

Side View

Front Quarter

Rear Quarter

“Lobster Claws”

A Very Clean Engine Bay

Front Interior

Rear Interior – Seats Fold Down

 

November 17, 2017 

The Trip Home and Registration in Virginia

I woke up around 4:30am and got an early start for the trip home. All the travel was uneventful. I arrived about 12:30 pm and before taking the car off the trailer, Judith and I headed for DMV to see about getting the car titled, registered and licensed. That process took a little while but wan’t too painful.

Initial Drive and Wash

After getting home and taking the car off the trailer I, of course, had to take it for a little spin around the block and then wash her before going in the garage!

Home!

A Little Cleaning Before the Garage

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