Statistics can't be accurately gathered for the factory bearing because the numbers to complete the equation can't be gathered.
This week we received one engine with a failed bearing, it was a late style 06 and later bearing. It's the "featured failure" in this months newsletter that I am working on today because of how collateral damage is what killed that engine.

I received 3 other failure calls this week, two were IMS and one intermix.

Of the cars we have retrofitted here (215 all serialized) we have not had any failures. This is due to the procedure that we employ coupled to the after install support and engine oil that is used.

The factory seals might be fine if they stayed sealed, thanks to oil temps and oils that sees heavy fuel intrusion, they don't.

I wanted to address this separately.
The races and cages of the ceramic IMSR are still ferromagnetic and will trigger an IMS Alert. We have carried out this specific testing all through 2011.

BUT in applications where the IMSR is employed the IMSG is more useful in alerting the driver of the other ferromagnetic wear metals within the engine.

Sorry if I wasn't clearly asking the question. I meant to ask you about the statistics of the LN bearing not the factory ones. But, mike and jfp have indicated the figures. You don't have to answer if the numbers are right. Thanks,

That's a gamble as well isn't it? Considering that ferrous bits can come from other sources and affect the LN bearing which is not sealed.

Wonder if the magnetic drain plug might actually help in drawing and keeping the bits confined in one area and away from the bearing to some extent.

Won't the heavy metal cage be slower accelerating/decelerating than the ball bearing itself? Causing the ball to bang the against the cage, accelerating wear on the cage? Eventually banging chips in the ball itself as the ceramic ball sharpens the the edges of the metal cage?

I think that is why bearing companies use nylon or Teflon cages with ceramic balls as they are lighter and can keep speed with the ball itself.

Sorry, you are wrong..
The cage is there to only lightly retain the balls (the balls run in the so called "deep groove" of the bearing), and they dont come into contact because the lubricant (grease or oil film) acts as a buffer - the gap between the cage and balls is measured in microns.
The weight of the cage is measured in milligrams - the speeding up or slowing down would be insignificant unless your grease was so thick it caused drag.

Sorry,, but you are wrong,, They are using oil lubrication in the LN bearing and very thin at that. It will be like a knife being sharpened with a oil film against a ceramic sharpener. The cage weight will matter even in the milligrams when you jump on the accelerator or slamming on the brakes. Anyways, I will look up the link on the bearing site I read it on, and post the link.

Log onto www.rentech.org.Forums and under heading for 996 Series (Carrera, Carrera 4, Carrera 4S, Targa
see Casper Labs Ceramic IMS Bearing.
The whole gambit is interesting but especially post #39, on page 2 from Casper Labs head honcho regarding steel vs plastic cages and ceramics in general. Casper are Aero engineers have been trialling an alternative IMS bearing application.
Bill Ryan is far more experienced than I am in detailing the respective materials....


Our production bearings will be shipped with steel ball cages. We have tested two types of steel designs, nylon, and an exotic made of a low density phenolic. The phenolic one is put in a bell jar immersed in Mobil 1. You pull a vacuum on it, and the oil gets sucked into the phenolic. It will wick enough oil for years of dead storage to start-up lube a ceramic hybrid...... even if the sump oil level is below the bearing. These have to be custom CNC machined, and double the bearing cost. If you really want the phenolic cages, we can special order them (2 week delivery).

Why did we pick steel as the baseline? Many reasons, 1) steel cages are fitted more loosely to the balls due to the limitations of forming sheet metal. This gives the consumer the perception of a lack of quality in a precision device. They move around a bit relative to the ball. Does not hurt the bearing, but perception can be a difficult thing to get around. 2) Nylon nests the balls precisely and has slightly better capillary attraction for the oil film between the ball and cage (providing more oil "storage"). 3) If either of these cage materials gets some level of damage, the nylon will not damage the OD race when the hard ball rolls over a piece of it. 4) From a temperature standpoint, steel cages have the highest rating. The phenolic is second highest (about 350F), and nylon the lowest. The highest temperature rated nylons are just too close to this boxer engine's red line coolant temp (remember this engine uses a coolant/oil heat exchanger). We never encountered this problem, but it is too significant to consider production worthy. If this really catches on, we may consider investing in the tooling to mold out of a higher temp plastic, none are available now in this size.

We ship the bearing with a very, very light lube that really lets you feel the rolling action. If anything gets in the bearing during assembly, you will feel it. Once we are certain it is clean, we take a veterinary's large animal syringe (.040" needle) and inject some engine oil supplement to both rows of balls before slipping the support in place. This is where the looser fitting steel cage comes in handy, you can get the needle past the first row of balls.

Billl Ryan
Casper Labs, Inc.

Steve, All this says is.... nylon "could" melt if you cook your engine but didn't give the temp. Phenolic was too expensive, but is suited for the job (350F) BUT, nylon and phenolic are NOT steel. Also it states they only tested 2. He also states... the cage won't damage the ball, but I don't see where the the ball won't damage the cage. Plus, he is talking about assembly of the bearing here, not a test of accelerating/decelerating of the ball damaging the cage.

Ceramic balls are lighter and harder than steel and will move much faster than the steel cage causing wear within the cage. The bearings life will be shortened with steel cages, and its a wait and see at this point until bearings do fail.... as the root cause, it is an unknown at this point. And I hope it is shared with the group.

Maybe thats why the gaurdian came into play?

No, the IMSG came into play because of the huge plunge in Boxster and 996 values that could make a retrofit process worth almost half as much as a car and if a failure occurs the engine could cost twice as much as the car is worth to repair.

The IMSG is seamless and integrates into the car as a simple DIY process, not requiring any special tools or knowledge. The installer also doesn't risk making a mistake that can cost them an engine if the process isn't carried out correctly.

The IMSG isn't appreciated by everyone, but it has gained respect from its installers thus far.

It has gained my respect for sure. Though I am not happy about the cost. But that's just me.

I drained the oil and found maybe 3-4 tiny metal bits. The filter had a few small black plastic bits as well. Very tiny. My clutch is fine but, there is slight oil leaking from the bottom of where the engine mates to the tranny. So am going to wait it out with the IMSG installed. The way I see it I will not be totally confident with the IMSR alone installed. So, will need the IMSG as well and this will be one step closer to a good night's sleep.

Thanks all for the discussion. Very informative and helpful.

http://986forum.com/forums/uploads01...1330384030.jpg

We make bundle packages with IMSR and IMSG quite often, it saves a little money.

Jake,
i ordered the guardian. Honestly I want to wait for Pelican kit to compare as I'm still on the wall with the ceramic factor. PP kit is 3-6 weeks away is what I'm told. Anyway it gives me some time to drive around with my new buddy Guardian.

Removed the oil pan to prepare for IMSG install and surprise! Metal pieces in the pan. They look like someone left some aluminum tray inside that got chewed up. I'll post pics tomorrow but at this time I am not a happy person. Need to drop tranny and take a look at the ims. since the entire suspension, axle is out better to do it now than later. :mad:

Run a magnet around the metal and see if the pieces stick to the magnet.

A bearing filled with grease does always have a specific limited lifetime compared to bearings that are lubricated by oil. Guess that Porsche knows the lifetime here but this is of course only possible to calculate if the grease is kept inside the bearing.
However , original intention must have been a lifetime well beyond 200,000km

In Mr Rabys solution lifetime will probably be very good as long as there is no loose debris entering the bearing which cant be guaranteed. Just look inside your oilfilter every oilchange.

I guess that no double row bearing with the grease kept in place has failed yet.
The single row bearing was probably some kind of costcutting project as the IMS failures where uncommon the first years and there was room for lower spec of the bearing.

When it is time for my next clutch I will,( if they exist) use a standard bearing but with upgraded seal spec and grease that can take more than 120 degrees C.
This will be done in combination with a low temp thermostat and 10/40W oil

Until then I will feel very safe with the IMS guardian.

I am in a similar boat. I can't justify another $600 on this engine. I went down to the local bearing shop and bought a bearing for $17. The bearing in both the failed engine and the replacement engine we bought were both good.

John

One thing I don't understand (or not educated on) is why am I finding the metal pieces at the bottom - oil pan. These should have gone thru the filter and actually should be in the filter no? Don't think those pieces just came loose when I turned off the car and then proceeded to drain the oil and removed the pan.

Just tried feelyx's suggestion and used a magnet. NONE of the pieces stick. There are also some tiny pieces black in color. Plastic maybe?

So, if the LN bearing is not sealed and is lubricated by oil, and the contaminants (metal) can come from elsewhere, there is a high probability that it can damage that bearing as well. So, a sealed one is much better bet not considering lubrication factor? Your take on an upgraded seal bearing makes a lot of sense to me. Of course the IMSG would allow just in time intervention if a disaster was going to happen in all cases. But, no such bearing exists does it. Can a OEM bearing be purchased, upgraded lubrication and upgraded seal be made to order?

Reading up on bearing failures it's normally a result of the race guide or the balls suffering damage. Typically this damage is caused by either foreign particles entering the bearing races or the bearing race/balls fragmenting as a result of excessive heat from running at too high a speed /load or with insufficient lubrication. The advantage of ceramic or composite materials is they are less affected by temperature or foreign particles. Assuming Porshe specced the bearing correctly for speed and temperature the only realistic cause of failure is that the lubrication is washed away or that foreign particles enter the bearing causing deterioration. Either way, there is a very strong case for fitting a bearing that can operate with less lubrication or oil lubrication rather than grease and that is more resilient to foreign particles in the race guides.

A question for Jake and flat six innovations at this point. With full ceramic bearings available , why is the solution offered using a hybrid rather than full ceramic ? Is there an issue with full ceramic bearings in terms of load or shock resistance that is required in this application ?
For instance the bearing listed below meets the temp requirements for the application
6204 Full Ceramic Bearing 20x47x14 Ball Bearings

Or the full compliment Silicon nitride bearing
6204 Full Complement Ceramic Bearing 20x47x14 Si3N4 Ball Bearings

I assume the bearing offered currently is something like this ?
6204-2RS Hybrid Ceramic Sealed Bearing 20x47x14 Ball Bearings
SKF - Product data

Feelyx,
Thanks for the suggestion. The pieces are not sticking to the magnet. What am I supposed to conclude from this?