Holdfast996

Someone asked for the before shot? Just dropped.

steam_mill

Where are you having this done?

peterp

Curious if you would not personally replace it because:

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).

Porschetech3

As a frugal mechanic of more than 40 years, I agree with these statements. On a new engine that sheds a lot of break-in debris, a sealed bearing would be ideal over a non-sealed bearing. On an engine that has had a bearing shedding debris also a sealed bearing would be nessesary. Once the debris production has stopped, either from break-in or repair/replacement of cause, the filtering system must catch all the debris, then a non-sealed bearing would be more reliable due to more dependable lubrication. The filtering system on the m96 is not much basically different from a conventional engine (other than the by-pass location in the bottom of the canister), but the drain back of spent oil in quite different in that there is not a direct flow of drain back, so debris can linger and hide for a lot longer before being captured by the filtering system.

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.

Holdfast996

Peterp - its both. A and B

NuttyProfessor

Holdfast, I completely respect your position on the subject. I hope you get lots of years out of the engine. Please report back good or bad. rock on!!!

Fredycrudas

cds72911

Fredycrudas

993GT

^that's a single row

Fredycrudas

993GT

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