First time I heard of this theory... IMS

[JFP in PA]

Originally Posted by Nine8Six

Ppl generally fear what they don't understand. The point of this thread is find out why Joe's car is perfectly fine but Emma's car had a IMS failure.

I think this is what ppl wants to know. They also want to know whether it is a general design flaw or affecting a certain group of cars only. Fair enough questions if you ask me.

Not sure ppl wants to hear that "it can happen, and it does". Speaking for myself I have no idea how this translates in engineering terms. Not that I care mind you but some actually does. A lot apparently

From experience, there is more than one factor involved in the IMS failures. There has always been the possibility that some of the OEM IMS bearings simply were not good. When one fails catastrophicly, there is little left to analyze, so that has never been confirmed to my knowlege. Off center IMS shafts are real, once removed from the engine they can be tested for this, and some rebuilders even "stockpile" good ones for future customers. But without a method to test them while they are still in the cases it prevents you from knowing if a shaft is good or bad. And if you think about it, a shaft that is not turning true, and is at least partially loaded down with oil that has leaked past the IMS is constantly beating the Hell out of the bearing, regardless of whatever else is going on. Problems with off center or non concentric case openings such as the RMS where identified as an issue by Porsche several years ago when they released a "go/no go" tool to test the RMS opening; and if the case failed, the engine was replaced as there was no realistic way to repair it. It does not take a rocket scientist to realize that the IMS flange opening is just a couple of inches below the RMS opening, and looks exactly like the RMS opening, only smaller; so if one is wrong, the other one could be as well. Everyone here has probably read about chain wear pads failing in these engine, so what factor does slowly developing "whip" in the long chains connecting the IMS shaft to the cams play? Again, data is thin and sketchy.

Only someone like Jake, who spends most of his life staring at the internals of a large number of these engines is really in possession of most, if not all of the facts. And unfortunately, both as the direct result of people copying what he has spent years developing, and the grief he has incurred on websites, he has pretty much stopped saying a lot, or charging for access to that knowledge.