IMS thought

[fm1082]

I know a bit about bearings and seals from my job dealing with large enclosed gear drives and related equipment. A lot of time is devoted to keeping ball, roller, spherical etc. bearings and seals alive in hostile environments. This got me thinking about the IMS issue.

Has anybody thought about using a sealed one side ball bearing or just picking the seal out of a still good in-place bearing and installing a small grease tube in the cover which could be extended out of the bell housing with a grease fitting? I understand that you would have to drill & tap the IMS cover and maybe relieve the bell housing so you could get the tube between the block and transmission and there might not be enough room to do this. (I have only seen pics, not had one apart) but a few pumps of grease at every oil change and that bearing will never fail.

I say this because many gear drives that normally use pressure or splash lubrication use dry wells on the bearings in some applications. This is usually when leaking oil would contaminate a product so the bearings have to be greased. If the IMS bearing was open on the cover side, grease would just fill the cavity and force into the bearing. If something like a lithium grease was used, you wouldn’t have to worry about engine contamination because that will dissolve in the engine oil just like engine assembly grease.

Just thought I would throw it out there…

[WhipE350]

Great idea! Would the pressure from the grease packing at each oil change weaken the inner seal and cause it to fall off? If it did then wouldn't the splashing just wash away the grease? I suppose if this did happen then there would be no back pressure when greasing and it would be obvious a replacement was needed.

[Wayne 962]

There is a space between the bearing and the cover, so that area would be washed with oil and wash away the grease within a few miles, I think. Interesting thought though - I do believe there must be a good solution to this problem somewhere.

-Wayne

[fm1082]

Originally Posted by Wayne at Pelican Parts

There is a space between the bearing and the cover, so that area would be washed with oil and wash away the grease within a few miles, I think. Interesting thought though - I do believe there must be a good solution to this problem somewhere.

-Wayne

Originally Posted by WhipE350

Great idea! Would the pressure from the grease packing at each oil change weaken the inner seal and cause it to fall off? If it did then wouldn't the splashing just wash away the grease? I suppose if this did happen then there would be no back pressure when greasing and it would be obvious a replacement was needed.

Absolutely, the grease washing out is the entire problem with these bearings! lol

For design purposes, rotary lip seals are limited to about 7 psi positive pressure, since the seals in a brg like this are seated very tight, the grease should just push out the lip and not unseat the whole seal…theoretically!

The trade off is always this; a sealed brg will last IF you can keep it from getting contaminated, if you can’t, then you provide a way of lubricating it with grease or a flow of oil. I have seen gearboxes with sealed units, but there is usually another lip seal inboard that is there specifically to keep the gear oil away from the brg seal.

It seems like the basic problem is that just enough engine oil gets in there to dilute the brg grease, but not enough to keep the brg lubed. Since the grease washes out slowly (thousands of miles), if it could be replenished on a regular basis, we might be able to keep the IMS brg in the “safe” zone.

Obviously, Wayne and others have all the technical prowess needed to analyze this issue, I just wanted to point out that there is a wealth of engineering and application data on these problems out there. You just won’t find it in the automotive world because only Porsche has ever tried a sealed ball brg INSIDE an engine…and with limited success!

[mikefocke]

Because of the difficulty in accessing the area, how many would "forget" to grease it and you'd still end up with a failure.

[intakexhaust]

Grease bearing... accessing the bearing... interesting idea. Assuming it worked, take the thought a bit further; run a tiny remote orifice / line to an external nipple.

All aside, I'm still leaning towards the problem of hydrodynamics which burst seals that leads to balls wear to the bearing race to the extreme heat, to the cover seals leaking and so forth.

[blackcrow]

I believe the LN ceramic bearing is an "open" design...

[Tinsby]

I can't get over the fact that "P" in their infinite wisdom ever thought the IMS itself was a good idea, let alone the sealed ball bearing. I realize you have to turn the camshafts but to expect a bearing filled with grease to last any amount of time, in an environment filled with oil, and constant changes in temperatures and clearances is folly imho.

I always bemoaned selling my 2004 Anniversary Edition Spyder, but when I owned it I was ignorant of the IMS issues. Now I am glad it's gone, someone got a great car but I couldn't have lived with it, knowing there was a ticking IMS bomb waiting to go off at some point. In the 70's I rebuilt hundreds of VW motors that had swallowed the #3 cyl exhaust valve so I know the devastation valves contacting pistons can have.

Adding a line with a Zerk fitting to lube the IMS bearing is a bit dicey I think, you'd have no way of monitoring the pressure of the grease you are pumping into the bearing race. Nor is there any way to tell if you haven't pushed the seals out of the bearing in the process.

I am happy to have a new Boxster without the bearing and shaft, that is not to say I don't feel the pain and worry others with earlier cars are experiencing.

Is there any data on the failure rate of the LN Ceramic bearings or their life expectancy?

I also noticed something in my years in the business. For whatever reason it seems that people that run the hell out of their cars seem to have less problems than those trying to preserve the car and drive it normally. This seems to be an inverse Murphy's Law rule that is undocumented but understood.

It's great that there are so many solution's being tried to alleviate the built in problem. But to me, it's a design defect that doesn't belong anywhere near a car with a Porsche emblem on it.

Regards,

J T

[mikefocke]

When last I checked 2 months ago there were 2k+ of LN bearings with the oldest dating to Aug 2008. I have heard of no failures attributed to the bearing (and I read 6 forums daily). They are recommending a replacement or at least inspection with the next clutch job for now but once there are more results from those they may know more about the reliability.

Keep in mind just how few of even the Porsche units fail. No consolation for those victims, I know. Just that the sky isn't falling.

[dmatz]

I just suffered a 2004 Boxster (58K) engine failure which has all the earmarks of the IMS (still awaiting a postmortem to confirm). The IMS bearing failure is a defect which should have resulted in a recall, and people at Porsche dealers have admitted as much to me. Recalls are triggered by complaints to the NHTSA. NHTSA complaints and investigations can be researched at their website: Vehicle Owners | Safercar -- National Highway Traffic Safety Administration (NHTSA) . Complaints can easily be filed there. Between MY 2000 and 2010 there were only 6 IMS failures reported with std or S Boxsters: 1 in 02, 4 in 03, 1 in 04 - not enough to trigger an investigation, much less a recall. I assume this is the tip of the iceberg. If everyone with IMS failures went to that website and filed a complaint, perhaps an investigation might be triggered. The person I talked to at NHTSA, when I described the IMS failure, said "tell your friends".