168glhs1986

Sellers say not a problem. Buyers say a problem. Don't even mention bore scoring. That's the real issue.

max911

And just how were the owners supposed to "maintain" a sealed bearing?

Bean counters apparently overruled engineers in Stuttgart on the sealed beaing vs oil fed plain bearing design decision .

CharlesLS

Just hit 150K on my Boxster with factory IMS. Don't really have the funds (nor plans therin) to replace it.

If it blows, I'll weld a 2.5L Subaru engine in the thing. Or take it to the junk yard for scrap value.

¯\_(ツ)_/¯

mikefocke

Maintenance starting out with frequent oil changes using the right stuff done at the right time. Or removing the seal when the trans is pulled for a clutch.

max911

Frequent oil changes will help the longevity of the engine as a whole, but will have little effect on a sealed bearing. How could it?
The IMSB failed on low mile cars, high mile cars, well maintained cars, neglected cars. The bearing has also survived in most low mile cars, high mile cars, well maintained cars, neglected cars.
So that tells me that maintenance is only a small part of the issue.

I agree on removing the seal while doing a clutch job. The heavy oil mist in the crankcase has seemed to offer enough lubrication to the ball bearing for those that have tried it.

I chose to eliminate the ball bearing and go with an oil fed plain bearing. (IMS Solution).
That's so i can worry about the other 10 modes of failure for the M96 engine- LOL

Cheers

BondJ

There are a number of reasons attributed to IMSB failure. The maintenance-attribution is thought to be oil temperature. If the oil temperature regularly runs high enough the soft rubber silicone-based seal that protects the bearing grease will break down and wash the grease out of the bearing, accelerating failure. As oil temperature per RPM will increase with mileage, one way to negate this is to change the oil regularly.

Whatever, the original Intermediate Shaft Bearing was a p*ss poor design

elgy

Then there are the IMS bearing failures that aren't.... IMS bearing failures. I have seen several such reports including the engine in my 2000 S which I bought with a seized engine. A reputable shop claimed was the IMSB. When I tore the engine down it was a spun rod bearing and the IMSB was just fine.

CharlesLS

Post #22 is basically my understanding on the IMSB situation too.

We will never know how many IMS bearing failures weren't actually things like that or things like timing chain guides, tensioners, vario cam pads, etc.. When any one of these items go basically everything remotely related gets wrecked too, deleting clues as to which part started the fight.

Basically, most people don't have a clue, making all "data" on the IMSB subject just guessing only with extra steps.

mikefocke

Frequent oil changes and oil changes just before hibernation help the bearing sit in fresh oil and not oil that has water/condensation in it. Does the bearing sit in oil? When the engine is off? Sure. Look at all the seals that have been reported as degraded. Look at all the observations from folks who have looked at their IMS bearings.

The bearing gets lubed by grease initially but then in mist from the crankcase when running and sitting covered in oil in the crankcase when stopped. As the seals deteriorate look at reports of what is sitting between the races and the *****.. Again look at the postings from those who have lockd at their bearings.

You are delusional if you think this is a sealed bearing for life. Initially, yes. But after a while ...

Tom R.

It is sealed for life. Life of the bearing. However long or short that may be.