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M. Murphy's Avatar
 
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IMS bearing failure

I have read forums and watched videos ( including Pedro's ) on how the failure occurs. Because it seems air and oil are trapped in the hollow shaft and end up contaminating the IMS bearing lubricant I wonder if anyone has considered drilling several small (.050) holes in the shaft. I realize this would have to be done coinincidental with an engine teardown. This would allow release of any oil captured and equalization of air pressure. If it were possible to try this and if it resulted in the bearing lube not being comprimised doesn't it make sense that the bearing life would be greatly increased?
Old 06-27-2018, 04:57 PM
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Isnít part of the issue that the ball bearing lets oil in which therefore ruins the lifetime grease lubricating the balls. So drilling holes would only speed up the failure if Iím not mistaken.
Old 06-27-2018, 05:30 PM
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If I understand correctly the air in the shaft/tube heats and cools expanding and contracting. The oil migrates through the bearing seals, some becoming trapped in the tube and becomes rancid then acidic. The acidic compound then gets into the bearing causing damage. To me it seems small vent holes would allow equalization of air pressure and allow oil to leave the tube.
Old 06-27-2018, 07:08 PM
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Ahh drill holes in the shaft, wouldnít that let oil from the engine case into the otherwise sealed shaft?
Old 06-27-2018, 07:10 PM
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And allow it out again.
Old 06-28-2018, 01:21 AM
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Drilling holes in the shaft is a bad idea on several levels, primarily for strength reasons as the shaft is thin sheet metal; plus IMS Solution equipped cars actually put a plug in the shaft to seal it up, which goes 180 degrees against your logic. It is actually better to keep oil out of the shaft in the first place, again for multiple reasons....
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Old 06-28-2018, 01:30 AM
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Wrong thread somehow. Oops

Last edited by feeshta; 06-29-2018 at 06:01 AM..
Old 06-29-2018, 05:56 AM
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I asked this question in the spirit of " the only stupid question is the one not asked". My impression, probably from Pedro was that the major failure element was the sealing of the tube and resulting pressure differential. Although I have not actually handled a tube my impression from the videos was that it is not delicate or fragile. Oh well.
Old 06-29-2018, 01:10 PM
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Quote:
Originally Posted by M. Murphy View Post
I asked this question in the spirit of " the only stupid question is the one not asked". My impression, probably from Pedro was that the major failure element was the sealing of the tube and resulting pressure differential. Although I have not actually handled a tube my impression from the videos was that it is not delicate or fragile. Oh well.
The IMS shaft can actually collapse and fold over on itself during an IMS failure; sturdy it ain’t. Pedro has said a lot of things that I cannot agree with, like it isn’t the bearing, it is the lack of lubrication; well if that was the case, dual rows should fail more often than single rows, which is not the case either.
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Old 06-29-2018, 06:03 PM
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One man's way of looking at the IMS issue.

Oil getting into the bearing is not the problem, it is how much and how clean and how much of its lubrication qualities get used up while inside the bearing.

Many replacement IMS bearings are designed to be lubricated with a combination of immersion in the crankcase oil when starting and with the oil mist that occurs naturally within the crankcase when running. They run for many tens of thousands of miles that way. There is a shop in the UK that removes the seal thus permitting the oil to deliberately wash out that "permanent" grease and they run the original bearings.

The problem with oil getting into the bearings may be that the seals, being partially still intact, don't allow a sufficient amount of grease and oil to get out and thus any contaminants sit there in oil whose lubricating properties have been compromised by time and temperature and overuse and chew at the balls and races. Remove the seal and the oil flow more freely and gets exchanged with cooler oil and potentially the nice clean oil you just put into the crankcase.

Even better is no seal and a better bearing. Porsche underspeced the original bearing characteristics and private suppliers have done a lot of multi-year investigations into better designs with better materials. Tens of thousands of bearings have now been swapped for better designs.

Perhaps best but expensive is a completely different bearing type with a filtered oil feed.

Here is a good starting point for reading.
Old 06-30-2018, 11:08 AM
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