Why the IMS bearing fails, another theory

[southernstar]

Jeff, there is no question that there are areas in the engine where there is oil, a 'spinning', or at least moving part and air and that this can lead to aeration, necessitating an AOS for emissions purposes. My point is that after the air is pushed out of the bearing during initial start-up, there should be no air in the IMS bearing or housing due to the pressure feed. Without air, I don't see how there can be aeratioin in that part of the engine.

Regardless, it also has to be rememberd that the AOS is there as an emission device, not an aid to lubrication. Furthermore, AOS failures have typically occurred not as a result of marginal increases in aerated oil (as can occur after brisk driving), but due to failure of the rubber components inside the plastic body.

Brad

PS Truly enjoyed this 'debate' but, as Jake Raby points out in a parallel thread, it may utlimately be incapable of resolution.

[JFP in PA]

Originally Posted by southernstar

Jeff, there is no question that there are areas in the engine where there is oil, a 'spinning', or at least moving part and air and that this can lead to aeration, necessitating an AOS for emissions purposes. My point is that after the air is pushed out of the bearing during initial start-up, there should be no air in the IMS bearing or housing due to the pressure feed. Without air, I don't see how there can be aeratioin in that part of the engine.

Regardless, it also has to be rememberd that the AOS is there as an emission device, not an aid to lubrication. Furthermore, AOS failures have typically occurred not as a result of marginal increases in aerated oil (as can occur after brisk driving), but due to failure of the rubber components inside the plastic body.

Brad

PS Truly enjoyed this 'debate' but, as Jake Raby points out in a parallel thread, it may utlimately be incapable of resolution.

From what I have seen (videos) of the pressurized oil feed into an open bearing, it does not flood completely while in operation, there definitely seems to be an opportunity for entrainment, much like what happens in the vortex of a kitchen blender.

[thom4782]

Originally Posted by southernstar

PS Truly enjoyed this 'debate' but, as Jake Raby points out in a parallel thread, it may ultimately be incapable of resolution.

I disagree.

Two things are known. Ceramic bearings are better than steel because they are stronger, Unsealing these ceramic bearings is better than keeping them sealed because this eliminates the compromised lubricant problem that occurs when engine oil mixes with the internal grease lubricant. What is unknown here is whether DOF extends the operating lifetimes of unsealed ceramic bearings substantially longer so that is worth taking the risk to change the dynamics of the engine lubricating system.

To date, there is the track record of thousands of unsealed splash oil lubricated ceramic bearings which shows no dual row failures and a handful of unconfirmed single row failures. The DOF developers imply that this record results primarily from the fact that these retrofitted bearings are ceramic. They contend that splash oil is inadequate; it will lead to additional premature failures and DOF lubricated bearings will last longer by comparison. They don't say how much longer.

Whether DOF actually extends the operating lifetimes of retrofitted unsealed ceramic IMS bearings without incurring other engine problems will be known when when DOF cars attain comparable levels of retrofitted bearing use. For the 986 community, unfortunately, building that record for DOF will take years.

[southernstar]

I didn't say that NO conclusions can be drawn, only that at this point we cannot resolve the issue about the overall efficacy of direct oil feeding the bearing - and both the LN Solution and DOF utilize pressurized oil feed.

I did not say (nor do I believe) that a ceramic bearing would not be better than a steel ball bearing - and with DOF, one can choose either. Of course, seeing as the original dual-row bearings have now been tested in HUGE numbers for at least 12 years and have failed at a rate of less than 1% in spite of mileage, use and oil change frequency, I could certainly see why someone might replace it with a new steel dual-row bearing.

If you have the large single-row bearing that cannot be replaced or upgraded without tearing down the engine and do not wish to pay for the tear down, then IMO you would be better off installing DOF and removing the outer seal: at least that will ensure that the bearing does not fry itself on a mixture of old grease and oil (which seems to have precededed virtually all the IMS bearing failures).

If you have the smaller single-row bearing, then all choices are available to you. You believe that upgrading to a ceramic single-row would be the best solution; I believe that upgrading with a new ceramic bearing AND DOF would be better than simply an upgrade. I also believe that the LN Solution, if you can afford it, is probably the best solution (as it replaces the ball bearing with one that has proven trouble free, with proper lubrication, on the other end of the IMS). Who is right? As I said, at this stage we cannot know. Time will tell.

Brad

[JFP in PA]

Originally Posted by southernstar

I didn't say that NO conclusions can be drawn, only that at this point we cannot resolve the issue about the overall efficacy of direct oil feeding the bearing - and both the LN Solution and DOF utilize pressurized oil feed.

While technically correct, the Solution system utilizes a solid bearing surface, not unlike the crankshaft journal, while the DOF sprays oil into a spinning ball bearing unit. What happens to the oil entering each system at say 3,000 RPM is going to be totally different in terms of air entrainment, etc..........

[Jake Raby]

Waste oil from the IMS Solution is not sprayed uncontrollably within the engine. It simply returns to the sump and is never "in suspension".

The IMS Solution oil is delivered directly to the radial and longitudinal load bearing surfaces, once expelled it is returned to the sump just like the oil from the main and rod bearings.

[mikefocke]

Jake

How is it returned to the sump so that it doesn't enter the mist area of the crankcase and add additional oil to the mist?

What is different about the return of the oil to the sump done by the Solution from what you know of the way the DOF returns oil?

In experimenting, did you ever just just feed more oil into a ball bearing IMS and what were your conclusions? I would have though that would have been a thing you would have tried before thinking of the flat bearing.