Why the IMS bearing fails, another theory

[Jamesp]

I posted similar item in a string on Pedros IMS fix, and thought I'd put it out there on its own to get more feedback

I removed my IMS bearing and there was quite a bit of oil in the IMS tube. The shaft is not in the car, and yet no oil was seeping out past the bearing even though the shaft is stored such that the oil in it was being sealed in by the bearing end. So the IMS tube is effectively "sealed" by the bearing if the pressure between the inside of the IMS and the outside of the IMS is the same. My thought is that basic physics is at play here. Increased temperature in the IMS lowers the air density in the closed volume of the tube forcing air out at the bearing end. When the engine cools, the reverse happens and air, along with entrained oil enters the IMS tube. This slowly washes the grease out of the bearing by forcing oil under pressure through the seals, provided that is the path of least resistance into and out of the IMS tube. The IMS shaft is an unintentional pump which cycles a small amount of oil through the bearing end once with each engine heating and cooling cycle. The only inlet and outlet to this pump is through, or around the IMS bearing, and there is not much clearance around the bearing. I'm going to drill 2 very small breather holes through the meat of the driven sprocket into the open shaft area to eliminate the pumping action through the bearing, and allow a small exchange of oil in the shaft.

My fix is going to be: Breather holes, through the meat of the sprocket similar to IMS pinning holes (maybe I'll put in pins in as well, but I'll have to figure out how to do that correctly!) , A new greased bearing with an improved bolt - the stock bolt broke on this Box which is what killed the engine.

I believe the bearing design is solid (clearly not the bearing bolt though) provided the grease is not pumped out of it. I dumped a good 4 ounces (half a cup) of oil out of the IMS shaft. I suspect a good portion of that went past the IMS bearing seals washing out the grease.

Anyone have thoughts on this?