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do not even pretend to be in denial regarding an imminent IMS bearing death. it will happen eventually, by design of it, in any car that has IMS.
I will see how much this solution costs and if it is worth doing. my mechanic seemed to like it, here is his response:
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truth of the matter is ANY oil is good there, splash lubrication at least (remove dust seal) and now this little guy.... a simpler execution than the LN "solution" kit.
. . . I will see how much this solution costs and if it is worth doing. my mechanic seemed to like it, here is his response:
I just stumbled into the DOF product and in turn, this thread.
FWIW, the DOF for the non-removable bearing costs $800. And like a replacement bearing it would be done with a clutch job to reduce the overall labor costs.
This is such a waste of time and money, there's no evidence of failure of larger IMS in 2006+ cars, and the supposed solution here not only may do nothing, it might do more harm, specially if not installed correctly, and who knows if it's tested in all environments such as tracking, etc...
An extended warranty of only major parts (engine failure) is under $2K for 3yrs, which would be almost the same as this kit installed and it covers you for every sort of failure. If someone is super paranoid, maybe just get a warranty and be done with it!
This is such a waste of time and money, there's no evidence of failure of larger IMS in 2006+ cars, and the supposed solution here not only may do nothing, it might do more harm, specially if not installed correctly, and who knows if it's tested in all environments such as tracking, etc...
I agree, enough of the nondescript fear mongering with people saying they heard this or know of that. Perhaps some people are trying to drive up values of their 997.2 or other motivations.
Let's see some actual examples of '06+ cars with the larger bearing and with IMS failures. If it is inevitable then why were these cars excluded from the class action suit and settlement?
Boiler Inspectors 2006 IMSB failed at 140,000 miles. I think the warning noise is a muffled sound for a few seconds on start up. Sorta like an a/c clutch that's slipping n it stops after about 15 seconds. Complete failure sounds like a steel rod slapping n the tranny. No collateral damage unless you are wide open at speed (Conjecture). His was then driven carefully about 7 miles n made it home. Crazy in hind sight.
When the IMS goes out of balance it trashes everything at both ends. The debateable question is what threw the shaft out of balance. The statistics indicate that the early first generation bearings had only 1% failure attributed to them. Same with the third generation big bearing. The highest volume of "failure" is claimed to be in the second generation bearings of the 996 3.6 engines. However there are other issues that could be the cause of failure...including the Varioram Plus oil level/pressure needs, cam chain tensioners, and lubricant contamination from IMS bearing seal failure. None of those is the actual failure of the bearing on its own.
I have never felt the engineers at Porsche were idiots nor unethical. That doesn't mean they are perfect and haven't designed systems with weaknesses. However I don't think they released engines that are hand gernades. With my 03 996 and with my 06 997S I purchased aftermarket warranty service contracts and felt that was both prudent and sufficient.
My IMS was leaking, since I had to change the seal anyway, and since I track the car, I thought this would provide some extra insurance.
The system is well designed and my mechanic (independent porsche race shop) liked the design and now uses it for all their rebuild applications. Here is a photo of it installed. Since I did it I have tracked the car numerous times, no problems. Just makes me sleep better.
I don't know about the smaller IMSB s but the 2006 inner stub shaft only has a 1 mm clearance inside the shaft. This means when the ***** fail the shaft will move .020" towards the tensioned side of the tube and bounce around a .040" eccentric arc. I don't know what a high rpm total fail would be like but a start up idle fail GETS YOUR ATTENTION DARN FAST!
They don't go "out of balance". There is a pulsing like action as pairs of valves resist them fall down the closing side of the cam lobes.
If it is inevitable then why were these cars excluded from the class action suit and settlement?
There are a few issues with this statement.
1. The assumption that class action suites are "just" and "all inclusive" is simply not correct. The lawyers look for the easiest, big payoff. Going after the edges may risk failure. Lawsuits, once the ball starts rolling, are not about "doing what is right", they are about winning and making money.
2. The engine is also a unit identifiable by a single part number. These engine have multiple failure modes and I never understood why the class action suit didn't look at the engine as a unit instead of single component as they would cover way more years and have a higher failure rate. A lawyer who specializes in these matters should weigh in here. Again, the suite was about winning and making money. My point here is that the winnable class action suite is not always about covering all bad things, it is a judgement call about how to win. Personally, given that I am such an expert (sarcasm here), I would have gone after the engine as a unit and started in 1997 with the first iterations of this engine in the Boxster where porous blocks and slipped sleeves were common (if the engines failed some sort of porosity test, the pressed in iron sleeves to save the block... these then sometimes slipped down and banged against the crank and blow up). These engine designs had big problems and when my first Boxster 2000 S engine failed circa 2004, the mechanic who worked on the car said there were about five failure modes on these (Boxster and 911 - they are the same engine) engines at the time... but I can't remember his list.
3. Inevitability of failure. First, the only way to prove this out is determine what caused of demise of every car.... we are no way near that point in time to make that conclusion and by definition, would never be used as a point in a class action suite. However, I personally suspect this inevitability to be true. Why? Because this sealed ball bearing is intended to be "lifetime" and "non serviceable" per Porsche (in the early days of this engine) and I just don't believe in the concept of a moving machine part to be lifetime. This lifetime sealed bearing was a significant change from the plain bearing (force fed oil, no *****) of all past designs. The other end of the shaft employes the always-used plain bearing. Why this change was done is pure speculation but it appears obvious that it was for cost cutting reasons. To sum it up..... having a "lifetime" sealed ball bearing buried so deep and in such a critical use in an engine... well... to me, these engines will blow up at some point... the grease will cease to be effective, the ***** will wear and it will fail. I don't believe "life time" is really that.... sorry, I just don't believe it. To be fair to the engineers, their tests and design of this bearing may be to work for one million miles and therefore declared lifetime.... but obviously they made some sort of mistake.
I actually don't care much what the design is or what its intentions were, I just want serviceable items that we can change to keep the car running. I would actually be fine if Porsche said this bearing was serviceable and had a 250K replacement duty cycle.
Peace
Bruce in Philly
Last edited by Bruce In Philly; 07-10-2015 at 10:36 AM.
Some thoughts:
***I am told that Porsche is not responsible for design of the IMS-based cam drive system.
***The new Ferrari 488 is turbocharged, which is uncommon for S.F. Per Autoweek the twin scroll turbos use ball bearings instead of traditional plain bearings. Uh oh. Stay tuned.
***Roller bearing diameter is a key design parameter based, in part, on radial loads and angular velocity. The larger (newer) bearing is likely better able to accommodate the radial loads associated with low RPM (idle, street) operation. The small bearing is better equipped to tolerate higher RPM due its relatively lower angular velocity. This is consistent with claims that the smaller bearings don't seem to fail at the track.
07-01-2013, 01:04 PM
