Quote:
Originally Posted by ksjohn
I can agree with some of your point, but not entirely.
I have wondered if Porsche had originally sealed the end of the IMS as opposed to leaving it open might have made failing IMSBs a non-issue. But then that depends on what the majority mode of bearing failure is, rancid, acidic oil in the shaft eating at the bearing or simple failure due to stress.
But, the fact remains that the IM shaft does fill with oil on many/most cars and the oil has no means of escape, creating an oil flooded IMS. It seems to me that the EPS bearing being open allows the oil in the shaft to spin out past the bearing especially when subjected to centrifugal forces of a running engine, minimizing the amount of oil in the shaft while running. And new oil being metered through the pump shaft will provide continual lubrication for the bearing.
Regarding the oil drive shaft, I don't think it is a stock shaft with a groove cut in it. I looked, and they do not spell out how the shaft is manufactured. (which would be nice to see). But I am going to make the assumption that it has been engineered to account for the strength required in light of the groove. That is entirely an assumption. But then I have not read of any of these parts failing either.
I agree with you regarding the punch used to open a hole in the end of the IMS. It should be manufactured with a flange to prevent you from making the hole too big.
Now all of this is simply my understanding of the product and how it works. Many people here have vastly more knowledge than me regarding these engines.
But still, I pose the question: would their oil feed system and a standard un-sealed single row ball bearing be a viable option?
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One thing you may be overlooking is that many, in fact most, IMS shafts do not run true. This means there is some inherent "wobble" in the factory shaft even when is dry. On engines that have suffered IMS failures at low mileage, the amount of this nonconcentric movement is often profound, and is believed to have played a role in the early demise of the IMS bearings as they were simply being beaten to death by the wobble in the shaft, as well as the loss of the grease. As I have mentioned on more than one occasion, we always find the shafts at least partially filled with oil when doing an IMS retrofit, and a common comment we get from car owners after we install an IMS Solution (with the shaft now dry and plugged behind the bearing area) is that the car now seems to run and idle smoother. As we have not changed the amount of inherent wobble in the shaft, but have removed any collected oil and prevented any new intrusion, those observation may be the direct result of there not being any oil inside the IMS shaft to exacerbate the existing wobble inherent to the shaft from the factory. We have also observed that some Porsche engine builders often drill small holes into the IMS shaft, specifically to allow collected oil to escape.
So if oil inside the shaft seems to be an issue with multiple solutions, why would you specifically introduce it in the first place?