HiTempguy wrote:
Its not build quality in a sense though... its the fact that the motor will ABSOLUTELY NEED A REBUILD. And to get it done by a shop is f*&king nuts amounts of money.
I am praying they depreciate just the "smallest" amount more. If I could get one for $10k with a blown motor (awd of course), I'd drop it off at the shop that GRM highlighted that does the V8 conversion. $30k awd porsche DD with LSX reliability and mpg. Win Win!
Wow, quite an impressive level of ignorance.
Every Porsche engine over the years seems to have a ‘guaranteed will blow up and cost twice what the car is worth to fix it issue’ that soon get ironed out by the aftermarket. Mid years had thermal reactor issues, SC’s had chain tensioners that died, Carrera’s had head studs that snap, 993’s had air injection port issues etc. etc.
The M96/M97 engines have the RMS and IMSB (Rear main seal and Intermediate shaft bearing). The RMS seal has been improved on and seems to be fixed and is never more than an annoyance akin to LBC’s dropping oil.
The IMSB is potential a very significant issue, but you need to look past the hysteria. No doubt, if it fails in most (but not all cases) the engine is toast. The early cars had a single row bearing through some time in mid-01, then they switched to a duel row bearing from mid 01 onwards. The single row bearing seems to have about a 1% failure rate and the duel row a 4-8% failure rate. In some places I’ve seen a blanket 5%failure. In most cases if it fails the engine is toast as the intermediate shaft flays around and bits of bearings go thrashing through the engine and destroys all sorts of things. There are at least two cars on 986 forums that are still running post failure though. One in one of the Scandinavian countries that was caught just as it failed and another in Texas. The Texas car owner rebuilt the engine himself with a new shaft purchased off e-bay. As for preventing failure there seems to be several options. There is a device called the IMS Guardian which is basically a sensor in the oil prior to the filter looking for metal contamination indicating that the bearing is failing. Some people say that’s no good and my the time it warns you it’s too last. Most people plan on replacing the bearing when the clutch needs changing as once you’ve got the trans out and clutch off it’s very little extra effort to pull the flywheel and replace the bearing while you’re in there. As far as bearings are concerned. You can get a new Porsche one, get an upgrade kit from Pelican Parts for $165, or LN Engineering do an upgrade with a ceramic bearing for $650. Some people have reverse engineered the part number and sourced their own for less than $100. There are literally dozens of DIY How too’s out there.
Why does it fail? There are lots of theories. The best I’ve seen is this. It’s a sealed roller bearing with a seal on each side. It goes in the end of the hollow shaft. Some people speculate that as the engine heats up the air inside the shaft expands and forces itself out through the seals. Once it cools and the air contracts it sucks air/oil back past the seals. Slowly over time that oil washes out the grease in the sealed bearing and it gradually fails. I don’t know if that’s true, but it at least has the rig of plausibility around it, supported by the fact that oil is often found inside the sealed shaft. One guy (the Texan who rebuilt his engine with a used shaft) has drilled two small holes 180deg apart between the two sets of teeth that drive the timing chains on the shaft so that nothing needs to be sucked past he seals. But that’s just a theory by one guy.
General consensus seems to be Change the oil at 3-5K, use the recommended grade of oil and cut the filter open and look for debris with a magnet each time.
There was also the cylinder wall ‘D’ chucking issue with the early 2.5L Boxster and 3.4 Carrera engines only, it doesn’t seem to have been an issue with the 2.7, 3.2 and 3.6L engines. IT was a casting flaw caused by the insert mold casting of the Local cylinder liners into the case. It seems to have been an early issue which caused infant mortality. I think at this point any 2.5 or 3.4L engine will have passed the danger zone, but I wouldn’t want a 5k mile garage queen. Incidentally my next door neighbor had a new 98 Boxster that suffered from this and get a new engine under warranty.
There are literally hundreds of threads out there on IMSB’s on Rennlist, Pelican parts, 6speed, 986 forums etc. etc.
