docmirror

Ectually, the earlier the car, the lower the incidence of bearing failure. Highest bearing failure is on the 2001-2006 series II 996, and early 997. These are the single-row, small diameter bearing. Also, there is plenty of evidence that the machined shaft geometry was not very well maintained on those engines as production of the engines had moved from Stuttgart after a large fire in a Porsche facility. Combine a pretzel shaft, with a single row crap bearing, and one is very likely to be buying a repl engine.

The 'best' of the breed is the late 98, early 99 996 cars with 3.4L, M030, aero and early pre-PSM driver assists(220, 222, 224 options) with hollow sport 18" wheels(why did I sell it!).

Petza914

I disagree in some respects - see below.

History for the IMS Bearing is as follows:

• '97-'99 M96 Double Row Smaller bearing
• '00-'01 M96 Could be Double Row or Single Row smaller bearing
• '02-'04 M96 Single Row smaller bearing
• '05 M96 and M97 could have either the single row small bearing or the later single row large bearing
• '06-'08 larger M97 larger single row bearing

The early double row small bearing was the more robust of the two smaller bearings. The problem with that one was that it could shed ferrous debris for quite a while before actually failing. That is both good an bad - good in that you might see evidence of it failing prior to the actual failure - bad in that ferrous debris would cycle through the oiling system, and start clogging the oil filter to the point where the bypass valve in the filter would start allowing some of the oil to bypass the filter media and now you have metal circulating through the oil. It was for this reason that products like the IMS Detective were created, which was essentially a magnetic fork with a sensor and when enough metal had accumulated on the prongs of the fork to connect the two prongs, it would light up a warning on the dash.

The single row smaller bearings would often fail within a single oil change cycle, which meant you could look at the drained oil, examine the filter media and see no metal, and before the next 4,000-5,000 miles when doing your next oil change, have a catastrophic bearing failure, taking out the engine.

So yes, for the 996 cars, I agree that the earlier double row bearing was better, but should still be replaced. The last, larger single row bearings seem to hold up pretty well for normal street use, but not as well in track use. When you combine that with the interior improvements and aesthetic improvements, there's no doubt that the 997.1 is the better choice over any 996 and the market values reflect that, just like they do that the 997.2 is the better choice over the 997.1 in most situations.

docmirror

History for bearing FAILURE is exactly as I posted. 2001-2006, including all MkII 996, and all MkI 997 with small single bearing. That is the only class of bearing that the consent decree covered. Of course, an early bearing can and did fail.

The Flat 6 Innovation folks never made an "IMS Detective". They did make and sell through LN an "IMS Guardian". the principal is the same as found on most helicopter tail rotor and main gearboxes. A 'chips' light will be lit when enough metal particles bridge the two magnetic poles separated in the sump. If this happens, the owner should turn off the engine, tow to a service facility, and inspect the filter and see what's in there. I know of several cases where the cars have been saved by early detection of the bearing.

As far as the 997.1 being 'better' than any of the 996 due to market pricing, that simply reflects the lower age, and cosmetic improvements. Raby(and quite a few others) are of the opinion that the early 996(notwithstanding the price point) is the right water cooled 911 to have. Less bearing issue, less gadgetry to go wrong, and less 997 'bling' when Porsche decided that the swirl of Alcantara was more important than a light, tight coupe, and added bloat and cosmetics for people to gawk over.

Petza914

Yes, IMS Guardian is the product I was thinking of.

I don't know a single person that would choose a 996 over a 997. The 996 choice is almost always a compromise based on cost, except for maybe the 996 GT3.

FredR

Don't know much about the 911 platform but i was advised that the only reliable way to avoid the IMS issue that plagues the 996/997 platform is to purchase a turbo or GT3 as their engines are based on the 964 crankcase that is substantively different from that used in the n/a blocks. Whether such is accurate or not I have no idea but the gent who told me that snippet was "very credible". I understand Boxsters are also afflicted with the IMS issue.

How Porsche manage to get away with these major destructive type problems [like TBF on the automatics] escapes me.

Petza914

The Mezger engine design of the Turbos and GT3s does have an Intermediate Shaft, but it uses an oil fed bearing with no moving parts instead of a ball bearing, so that info is correct - nothing to worry about on those. That platform does have a couple other issues, like glued in coolant pipes that fail and cam timing hardware that can loosen or shear and cause the timing to slip, but overall that platform is very solid.

The IMS Solution product for the M96/M97 engines replaces the ball bearing with this same type of oil bearing of the Turbo & GT cars, so it is definitely a way to completely remove the IMS bearing issue from these cars, provided you have a car with the smaller bearing that allows it to come out of the case and be replaced.

928 GT R

I'll throw a bit of food for thought on the IMS bearing aspect of this discussion.

Our 928 friend Steve (former owner of the U-Boat XX8 928 GT) is a rather conservative driver most of the time. He also has a 2004 996 that just turned 391,000 miles! The car is going strong and last week he drove it to Atlanta, on to Florida and back to Minneapolis. The car runs great and is totally reliable. Steve did not have the IMS bearing serviced until 360k and it was in excellent condition according to the service technician that serviced the car.

Sooooo, Steve uses the car regularly during the summer and drives it at relatively low rpm's, but for long drives. Then the car sits for the 4-5 winter months in Minnesota and gets cold/dry started in spring.

One would think that the IMS would dry out in the winter and cause premature wear upon startup after winter. Not so?

One would think that the motor would wear because of his use of lower rpm's. Not so?

After thinking about this for any time, recognizes his high mileage comes from long trips with the engine fully warmed up. Short trips are the real nemesis with engine longevity. As Hack constantly mentions "with engine oil and coolant all warmed up" is the hero of engine longevity.

So, the death sentence for motors is likely any combination of lugging, over revving or just driving short trips and then parking it before the engine has a chance to burn off the starting condensate...

docmirror

Case studies with a population of 'one' are usually not worth much. Typical plain oil fed bearings in moderate use have exceptional longevity. Ball bearings, are typically lower, and the fact one person gets such long service from it, don't really say much about the population as a whole. However, the warn up and drive for a while is good advice for pretty much any engine. We've moved from lugging an engine to the all-consuming miasma of the 996 IMS bearing. I don't think there's a relationship to lugging and IMS failure, or, to anything related to the 928 engine.

The IMS bearing debacle was likely the second worst mistake Porsche ever made. The first was the Porsche Flug Motor(aviation engine), which almost sank them. Having said that, the 996, and it's little bro the Boxster basically saved Porsche from the previous mistake. Sales of the 996 exceeded all other models by a wide margin. Also, since there was a lot of parts compat between the two, production costs were minimized. Pretty much everything from the A pillar forward is the same on the 996 and Boxster(but some differences).