Quote:
Originally Posted by tonythetiger
Is this publically available and can you reference? Without doubt, the design is prone to failure, and even at the lower numbers, it's disconcerting. Id like to know more as I have found a knack for swapping these out in my simple home garage. (i am not a mechanic by trade) Folks in the industry (such as yourself?) will have the exposure to failure since they come to you when something goes wrong.
I haven't seen an IMS failure, but I have seen 3 different engines with cracked heads, always passenger side on the 3.2L. (high mileage 140K+) Suspension wear is another common issue on EVERY boxster I've owned or seen. Overall, this is a well-made car and the little things that are small frustrations or maintenance like leaking spark plug tubes, water pumps, cracked coils, window regulators, microswitches (everywhere) the visor covers, convertible top, etc. just come with having an older car and don't detract that much from the enjoyment, in fact the projects tend to be fun.
Catastrophic engine failure is different. I am replacing my friends IMS for a 2002 996 in the coming days just because he has been worrying about it for years. As easy as this repair is, except for the exorbitant price of parts, this favor will at least let him sleep easier. However, I regard the 900 price tag for a bearing and flange opportunistic. The pelican retrofit is priced favorably, but I'd like to see a stronger bearing in that kit to trust its fixed.
do others have thoughts?
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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.