Why the IMS bearing fails, another theory

[mikefocke]

Isn't there air in the crankcase into which the high pressure oil is forced? When I turn on my shower I get a fog on all the adjacent surfaces. Air has picked up the liquid.

Wouldn't that oil spray lead to a heavier mist which would then have to be removed by the AOS as the air in the crankcase is forced through the AOS into the intake to make room for cylinder blowby?

Wouldn't the ball bearings and the relatively large gaps between them allow more flow through into the crankcase above the level of the oil than solid bearings as in "the solution"?

[JFP in PA]

Originally Posted by mikefocke

Isn't there air in the crankcase into which the high pressure oil is forced? When I turn on my shower I get a fog on all the adjacent surfaces. Air has picked up the liquid.

Wouldn't that oil spray lead to a heavier mist which would then have to be removed by the AOS as the air in the crankcase is forced through the AOS into the intake to make room for cylinder blowby?

Wouldn't the ball bearings and the relatively large gaps between them allow more flow through into the crankcase above the level of the oil than solid bearings as in "the solution"?

When running, the crankcase is operating under a partial vacuum (~5 inches of water), your shower isn't.

[southernstar]

Consider 2 stroke engines - even though oil is drawn into the combustion chambers during each cycle in conjunction with both gasoline and yes, air, nevertheless the oil is still able to provide adequate lubrication. This is so even though in theory there would be a significant risk of 'aeration' with the movement of the pistons and piston rings combined with oil and air.

Even in a four stroke engine, wouldn't there be a risk of the oil in the cylinders becoming aerated, especially during the compression stroke? The oil is still able to lubricate or none of these engines would be able to function for any length of time. Again, it seems to me that the risk of aeration from a pressure oil feed to a bearing with NO access to air intake should not be a concern.

And Mike, oil is being forced into the crankcase regardless, is it not? Since the same amount of oil is being cycled through the engine, I just can't see how this would make things any worse. Or am I missing something? It also strikes me that if the oil is being aerated by the pressure oil feed to the IMS bearing, then the oil on the dipstick should appear foamy or frothy after a hard run. Certainly if it was too much to allow the anti-foaming agents in synthetic oil to overcome. I wonder if anyone who has installed DOF has checked their dipstick after a hard run and can comment on whether this is case.

Brad

[JFP in PA]

Originally Posted by southernstar

Consider 2 stroke engines - even though oil is drawn into the combustion chambers during each cycle in conjunction with both gasoline and yes, air, nevertheless the oil is still able to provide adequate lubrication. This is so even though in theory there would be a significant risk of 'aeration' with the movement of the pistons and piston rings combined with oil and air.

Even in a four stroke engine, wouldn't there be a risk of the oil in the cylinders becoming aerated, especially during the compression stroke? The oil is still able to lubricate or none of these engines would be able to function for any length of time. Again, it seems to me that the risk of aeration from a pressure oil feed to a bearing with NO access to air intake should not be a concern.

And Mike, oil is being forced into the crankcase regardless, is it not? Since the same amount of oil is being cycled through the engine, I just can't see how this would make things any worse. Or am I missing something? It also strikes me that if the oil is being aerated by the pressure oil feed to the IMS bearing, then the oil on the dipstick should appear foamy or frothy after a hard run. Certainly if it was too much to allow the anti-foaming agents in synthetic oil to overcome. I wonder if anyone who has installed DOF has checked their dipstick after a hard run and can comment on whether this is case.

Brad

There are reasons these engines have multiple air oil separators in them.......

[southernstar]

I realize the engines have AOS, but what I fail to see is how direct pressure feeding of the IMS bearing, which has zero access to air, can increase aeration of the oil beyond what is already occurring.

Brad

[JFP in PA]

Originally Posted by southernstar

I realize the engines have AOS, but what I fail to see is how direct pressure feeding of the IMS bearing, which has zero access to air, can increase aeration of the oil beyond what is already occurring.

Brad

I would think that spraying an oil with some level of film strength onto a spinning and irregular surface would definitely entrain air into the oil, even in a partial vacuum, otherwise there would be no need for a device to separate them.

[southernstar]

Sorry, hit send accidentally on the screen. Doh! See above for what I was typing.

[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.