Doing clutch, not touching IMS
#123
Drifting
A. You think it is not necessary (given condition of current IMS)
OR
B. You think there is more risk in replacing the original with an aftermarket sealed bearing (that is the same design as the original bearing).
#124
Rennlist Member
My personal take on stock bearings is that if the seal is failing and you're not replacing it, you might as well remove the seal - the path to failure is oil getting in there and losing its ability to lubricate as it never gets refreshed. Removing the seal - while adding risk of foreign object debris damage - allows old oil out and fresh oil in such that it's at least lubricated.
Whether or not I'd remove the seal if it isn't leaking yet, I'm not sure. Porsche put a sealed bearing in for a reason, and I think that reason is that the oil it sits in is unfiltered. My personal vehicle had metal shavings from a IMSB failure so I had to go with a sealed off-the-shelf bearing. It's been happy for six months now / 5000 miles.
Whether or not I'd remove the seal if it isn't leaking yet, I'm not sure. Porsche put a sealed bearing in for a reason, and I think that reason is that the oil it sits in is unfiltered. My personal vehicle had metal shavings from a IMSB failure so I had to go with a sealed off-the-shelf bearing. It's been happy for six months now / 5000 miles.
I've seen many engines have a failure of a new camshaft/lifter (especially on a new high/lift non-roller cam conventional engines), and debris laden oil. Replacement of the failed components and a flush and a few frequent oil changes have sucessfully repaired them. The ones which were not sucessfull are3 the ones that fail slowly, with debris that is small enough to pass through the filter and remain suspended in the oil that is not changed for many miles. This will damage the main and rod bearings and would even damage a "IMS Solution" as it is primarily a plane bearings just like the main and rod bearings with the same lubricating oil. Anything that will damage the main or rod bearing, will also damage the "IMS Solution".
For me personally, the decisions are based in economics along with probability.Being in the middle class (lower middle class) and having 3 cars with m96 engines, the Solution while being my first choice, would cost about 6k to equip all 3 cars, I could buy another 986.
To me the greatest contribution to the m96 from Flat6 was the idea of replacing the IMS bearing with the engine still in the car. This was revolutionary ! As before the only factory procedure was to completly remove, dissemble, clean engine, and replace the IMS shaft. I was under the impression that the Flat6/LN retrofit was intended as a repair to keep from having to do a complete tear down/ rebuild of the engine in instances of a IMSB failure. While it is obvious with the pre-qualifiing procedure now implemented,that it is not to used for failure repair,only preventative maintenance, I'm not sure if it was originally.
As far as economics go, if you are faced with an IMSB failure and decide to do as Boxman did and replace the IMSB with a sealed bearing and flush the engine and do a few frequent oil changes, the only thing you really risk is damage to the main/rod bearing and crankshaft. Since main and rod bearing would normally in replaced during a rebuild, the added cost of the crankshaft damage would be only risk(1k). So if you decide not to take a chance and rebuild with new cylinders/pistons, bearings, rebuild heads, chains, guides, gaskets, seals ect, you have spent 15k, or take the risk and spend 16k after the bearings fail( or maybe all the debris is captured and no failure occures)
I would never condemn any one from over maintaining/servicing or repairing their car, as an enthusiast there is no such thing and I'm often jealous of anyone who can do it.
As a recap. The best choice in my opinion if you got the cash in the "Solution". The ceramic/hybrid or non-sealed bearing is best choice for a well broken-in and pristine engine. A new engine or one that has had anything producing debris, a sealed bearing would be best untill the production or lingering debris is captured.
#126
#128
Drifting
Visual inspection once you remove the flange.
#130
^that's a single row
#132
post '99 3.4 (00/01) it could be either style and are unknown til you see it. 3.6 cars were all single row to my knowledge with 997 2005.5+ engines getting the large OD single bearing