Why the IMS bearing fails, another theory

[Jamesp]

Not the way I modified the IMS shaft. I put several videos on YouTube yesterday explaining why the IMS bearing fails, and showing how to modify the IMS shaft to prevent pressure from forcing oil through the IMS bearing. I found it very strange that a German engineering company couldn't figure out a ball bearing. Ball bearings are fairly well understood from an engineering application perspective. How is it Porsche got this wrong? Several times at that. Something else had to be at play, and looking at it, the geometry of the IMS tube itself creates pressure which will tend to force the grease out of the bearing and replace it with oil.

Here is a link to the YouTube video that may explain why the grease lubrication gets forced out of the bearing 1 986 IMS Bearing Failure Mode - YouTube If you click on my "channel" you should see the rest of the videos showing the modification of the shaft. Just so you know - this isn't spam or an ad, I put this out there as information to other 986 owners. Happy Boxstering!

[thom4782]

Saw the video...interesting.n Here's my question.

Given the two holes are placed directly opposite each other, why wouldn't the IMS tube partly fill with oil for the following reason? At times when the engine is off, one hole will be submersed and the other vented. The surrounding air pressure will then pump oil into the IMS tube until the outside and inside oil reach the same height?

[Jamesp]

The shaft will likely fill with oil when the engine is off, though it is possible it won't. When the shaft begins rotating at idle the oil will be expelled out the holes. I thought about one hole (unbalanced) one through hole, and one almost through hole for balance (less oil in the shaft), or two through holes. I went with two through holes to move the oil out faster at idle. At the end of the day I'm not sure having the second hole all the way through makes any difference from an oil expulsion standpoint but it will balance more accurately.

[moresquirt]

jamesp i believe u are on to something here,while u have the engine out or at least the ims shaft is it possible to do a test run with your theory,if it works as planned then u could patent the idea and help alot of porsche people.i personally am on the fence with some of thease new theorys but feel if i do nothing then i am playing russian roulette,for about 18 grand last time i cheaked,for me that cost would be the end of my porsche experience.

[Jamesp]

Replacing the ball bearing entirely appears to be a bullet proof solution, and there is a product out there that does just that. Keeping a ball bearing leaves the choice of either a closed greased bearing or an open face bearing which depends on either splash oil, or an added oil feed. My thoughts on an open bearing (admittedly without much data) is it seems if your going to have an open ball bearing, a ceramic bearing with an oil feed would be the way to go. Its all about adequate bearing lubrication. Another option, which is where I'm headed is to relieve the pressure differential across the IMS bearing and go back to a greased bearing as the grease won't be washed out if there's no pressure differential across the bearing.