I had my IMS bearing replaced with the LN retrofit at 40,000 miles..................

Is it possible that a faulty motor mount and the vibrations they cause could produce added stress on the IMS? Since the engine and tranny are joined, I suppose they would move in unison, but I'm not too familiar with that area.

I know mechanics doing the IMS upgrade have reported some OEM IMS are still in great shape and some are in bad shape. I wonder how many of the cars with a bad IMS were also advised to replace motor mount(s) when everything was torn apart.

... the Front Engine Mount is bad, you replace it.
If it isn't, you don't.
I don't think that one has any bearing (no pun intended) on the other.
When you drop the tranny, you leave the Front Engine Mount in place, supporting the engine so I don't think it gets a good looking at by many shops.
Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

Mine went at 10,001 miles. My mounts would have to have been bad from the get go for your theory to hold true, at least in all cases. I never felt excess vibrations in my car.

--db

I was just throwing it out there after reading a BABBLERS.ORG post about LN IMS retrofits. We have a local indy, Porsche factory trained and an all around great guy who has done has done at least 5 cars that I am familiar with. IIRC, 4 of the OEM IMSs were in decent shape and one showed excessive wear and play on a car with 35k miles. This particular car also had a badly warn motor mount and just wanted the thoughts our esteemed PBers.

on my '02 Boxster S. The OEM bearing was somewhat dry but not in danger of imminent failure according to my very reputable Indy shop in Tucson, Dearing Automotive. Since I plan on keeping the car, it only made good sense to replace the bearing instead of constantly worrying about it. Did the AOS at the same time as a preventative measure.
Some bearings fail, some don't. I can assure you, though, that I have much peace of mind now. My motor mounts were in fine shape with no replacement required.

I would not expect a correlation between front engine mount failure and IMS bearing failure.
And let's not forget, the IMS is only one of the ways M96 engines may meet an untimely demise.
There are also the "case pororsity" issues, and the "D-chunk" of the cylinder liner.

For what it's worth, I am running a 97 box with a 2000 3.4 (carrera) engine,
the engine went in with 20k miles, and now has ~85k.
I have done a few track days, and my drive to work is a bit like a sprint race,
and nary a single issue.
(well, my valve covers are leaking, but I can't seem to find a set of new gaskets!! [joke!])

I recently had a Used Oil Analysis done by Blackstone Labs... Real quality outfit that can tell you if there is any
-bearing seal material,
-Bearing coating material, OR
-bearing material present in the oil.

These guys are pretty familiar with IMS failures in M96 engines, and are looking for the materials that make up the IMS bearing,
to see if failure looms.

Of course this is not a guarantee, but there are few of those in life with an internal combustion engine.

-Brad