IMS failures on automatics?

[azlvr]

Originally Posted by JFP in PA

Let’s start with the simple: The Pelican bearing is the same as the factory bearing, from the outset, it was designed to be the low cost alternative, not the best alternative. So you would be replacing the suspected problem bearing with another one just like it.

If memory serves, the article was in a trade press magazine a couple of years ago that was talking about the class action against PCNA over the IMS issue, and its impact on resale values after the legal action closed. If the years have not addled my memory, it was also reported in and article in Excellence. Similar numbers have been posted on other websites as well. Porsche originally released numbers around 10% for the single row at the outset of the legal action in a deposition, but like most mechanical issues, the numbers continued to rise while the leagal action dragged on. Porsche took the quick “corporate” way out by offering a nominal cash settlement to all the co litigants and no admission of guilt, with the lawyers taking most of the $ as usual.

Over the years, we have seen several failures up close and personal; we even had one customer that had one fail while still under warranty, PCNA approved a replacement engine which the dealer installed. Six months later, the replacement engine failed as well. We knew the owner and the car, it was serviced religiously, and the owner was not one to abuse the car. When the owner picked up the car after the second replacement engine, he drove it directly to a dealer for another brand and traded it in.

At the same time, we have had customers put 100K, 150K, and over 200K miles on similar engines with the factory bearings and without issues. So the IMS issue remains a crap shoot proposition: Some engines seem they will never fail, other simply don’t make it. One theory about the whole ball of wax was postulated by a rather serious Porsche after market engine builder with some serious credentials. He commented about the well known RMS leaking issue were very low mileage M96 engines started leaking oil badly, noting that Porsche released a special “go/no go” testing tool the measured the concentricity of the RMS opening in the case, which tested to see if the case opening was actually centered on the crank center line, and which found many were not. PCNA approved new engines for any that failed this test while under warranty, and released a new designed seal that was a lot more forgiving of misalignment. His theory was if the RMS case opening could be off center, was it possible that the IMS opening just above the RMS could also be misaligned. While the PTFE RMS seal could make up for misalignment, the metal on metal IMS flange had no hope of doing this, resulting in weird loading on the IMS bearing in engines with misalignment. The same engine builder also noted that when he spun up IMS shafts on a lathe before pinning the rear gear to prevent it from slipping (it is pressed on, and yes it too is a potential problem point), he noted that he found a lot of run out at the bearing opening on quite a few shafts, which he tossed out rather than reusing. So there is a whole bunch of possible reasons for problems to occur, which leads us back to the crap shoot description; get the wrong combination and you lose, big........... It also plays into another fact: the oil fed solid bearing IMS Solution is by its design much more tolerant of misalignment than either a ball bearing or roller bearing retrofit, which may explain why there has never been a reported failure of a retrofitted IMS Solution.

If you think about it, an engine with case opening misalignment and/or a wobbling shaft could explain why an engine that was pulled after failure and sent back to the factory for rebuild, could fail a second time; the true problem(s) were never repaired, just new parts installed. And it became a problem waiting for a new owner.

It cost Porsche a rather sizable fortune, both in bad press and engineering and parts sourcing to totally redesign the M96/97 into the 9A1 without an IMS shaft; they did not go to that expense because the problem was a little one, or one that was easy for them to fix.

An explanation that makes complete sense. My 01 3.2 has 141k and runs fantastic, already had the cracked head at 103k and IMS changed at 90k. When the engine is done it's time for a 3.6 or 3.8 with IMS Solution.

[Gilles]

Originally Posted by azlvr

An explanation that makes complete sense. My 01 3.2 has 141k and runs fantastic, already had the cracked head at 103k and IMS changed at 90k. When the engine is done it's time for a 3.6 or 3.8 with IMS Solution.

Azlvr, IMHO, this would be the best choice if you Love your car and plan to keep it for a long time.
.

[Homeoboxter]

Originally Posted by Gilles

Azlvr, IMHO, this would be the best choice if you Love your car and plan to keep it for a long time.
.

Yes, if you are the anxious type and want to sleep well at night after pouring a lot of money into your engine. On the other hand, the main take on from JFP`s post for me is that if a Boxster ran 150k miles without IMS failure then the engine case has no alignment issues and the IMS does not have excessive run out, so putting the IMS solution in it is overkill. Increasing the performance will not affect the load on the IMS bearing.

[JFP in PA]

Originally Posted by Homeoboxter

Yes, if you are the anxious type and want to sleep well at night after pouring a lot of money into your engine. On the other hand, the main take on from JFP`s post for me is that if a Boxster ran 150k miles without IMS failure then the engine case has no alignment issues and the IMS does not have excessive run out, so putting the IMS solution in it is overkill. Increasing the performance will not affect the load on the IMS bearing.

Only flaw in that assessment is that the bearing design itself is also questionable; while misalignment may explain some failures, particularly low mileage ones, the concept of using a sealed bearing is not a very good one all by itself. Viton seals harden with age and oil exposure, allowing hot oil seepage to wash out the grease while not allowing enough oil in to properly cool and lubricate the bearing. While doing retrofits, we found many bearings that showed they were “on the way out”, with hardened and gapped seals, but had not failed yet (no metal in the filter or sump found during pre qualification). The residual oil the came out of the shaft after the bearing was pulled was very thin and stunk to high heaven (An indication it had lost most if not all of its lubrication and heat transfer properties), and the bearing itself was very loose. After being retrofitted with a ceramic hybrid that was open to oil mist lubrication, the engine ran without issues for another 100K miles before the owner traded it in on another car. It would be reasonable to assume that the original bearing’s poor condition was not attributable to misalignment, but rather simple lack of proper lubrication and cooling.

The moral of all this tale is that the IMS failure issue is way more complicated than most think it is, with multiple possible factors contributing to it.