ORIGINAL: Rodney Naghar
Thanks for your views in advance......from a now worried prospective buyer!
Rodney my opinions are likely to be extremely biased and negative because of the problems and treatment I have had with my 996 so take what I have to say here as either good or bad information. I will leave with you to decide.
I think there is no kidding around with the RMS issue. Go seek every Porsche Forum on the ethernet and you will see that it's the most talked about subject in regards to this marque. The RMS is a problem. I don't think I need to convince you or anyone else on that matter.
As for what it means. Well all cars have their share of RMS leaks. But in the 986 and 996 its is too common and especially for a car of this price. It is, after all, supposed to be the epitome of German engineering quality. The name Porsche exudes the meaning of quality and that's what we have come to expect when purchase these exotic cars.
Many say that the RMS leak is nothing to worry about and you should just live with it. Other's say its a serious problem as it can lead to future nightmares. All I can tell you is what I have learned after 5 RMS replacements and a knackered gearbox (which I hope to have fixed in January at my own expense).
The crankshaft has 7 bearings although all but the Front Main Bearing and Rear Main Bearing are shell bearings. The other two are encapsulated bearings that fit onto each end of the shaft. The seal we talk about so much is called the Rear Main Seal. It sits on the end facing the gearbox. There is a FMS (Front Main Seal) that is on the front of the crank and also an IMS Intermediate seal which is attached to the intermediate shaft at the gearbox end. The purpose of a seal is two fold: a) to keep the oil from seeping out of the engine and b) to prevent dirt entering into it (in the case of RMS vis clutch dust). If the RMS fails completely then there will be considerable ammounts of oil leaking and probably clutch/flywheel contamination. If it fails partially, then it will seep oil out to the bell housing. Over time this can build up and be swished onto the clutch mechanism (one guy on rennlist has just reported this exact problem happened to his 996). If the Main bearing is contaminated it may lead to its detruction as the contamination wears at the bearing mechanism. If the main bearing fails then the engine will have serious problems. If the bearing has play and the crank has a wobble (even by a thou of an inch) it may lead to gearbox and/or engine problems. Conversly, if the gearbox has a problem or is not splined into the clutch mechanism correctly (aligned) then it can cause excessive load on the crankshaft and thus lead to Main bearing and/or RMS problems. It's is also possible for the engine block to warp or the two block halves to become missailigned due to temperature changes (cooling) or incorrectly tightened bolts. Porsche has released a new set of "blue" bolts and there have been several changes in the RMS seal (I think 4).
Regarding engine damage: The fact that Porsche have produced several TSBs and different parts (bolts, seals, bearings and even engine block) is evidence that there is likely long term damage imminent. Consider also that Porsche often replace engines (especially in the US and for ROW warranty cars) for repeat RMS offending engines. This is evidence that there is reason to be worried. Why would they go to such drastic measures if it was nothing to be concerned about.
Regarding is it worth the risk: Well the cost of an RMS eplacement is at least 6 hours labour and possibly a clutch and flywheel. A flywheel is about £400 and a clutch about £250. You can get an RMS replaced at an independent for as little as £270 but then you will forfeit any claim with Porsche in the future if you should need it. If your car is within warranty then you are covered. But out of warranty and you are in my situation... with not much of a leg to stand on. If you sell the car and you pass on the problems then you may be liable for the repair costs by the new owner. In any case residuals of this car are falling rapidly because of the RMS and engine problems. If you're rich and can sustain the cost of running these cars with this knowledge then it is worth the risk.
Regarding engines blowing up: From what I have seen most of these have been cylinder lining issues. The 996 engine uses cylinder sleeves. These sleeves are made from highly porous materia (25% silicon, 75% air) which is cast into the crankcase cyinder bores. At casting time, the air escapes leaving only the silicon in the cylinder lining but this is known to breakdown due to condensation buildup in the cylinder bores which lead to the sleeves turning to paste. The resulting play in the cylinder bore causes the engine piston to shake and collapse. The debris spread throught the engine causes catastophic engine failure. The only answer is a replacement engine. Of course if a bearing or bearing shell should fail then the same problem occurs.
Regarding Porsche's attitude: Well they are, after all, a public corporate buisness with a sole aim to satisfy its shareholders. They are not in the business of doing anyone any favours. Saying that, I have to be fair and say that PUK do "normally" offer good-will on a car that is 5 years old or younger. But after that your on your own. The main issue is that so many 996 (and Boxster) owners have reprted RMS failures and engines blowing up at low mileage. Much more than the norm. In many cases there are multiple RMS failures reported as in my case. But Porsche refuse to acknowledge the problem. Furthermore, it is clearly a manufacturing fault or defect in manufacturing process. If it wasn't then they would not have come out with new types of parts in an effort to fix the problem and it would not be so common. It also would not show up until the car has done considerable mileage but the RMS has been known to fail on the showroom floor in a car with delivery miles. The fact that it's a manufacturing defect means they have sold their goods without them being fit for their purpose and as a result they have breached the Sale of Goods Act of 1994. Then there is another question, why is that we don't have FMS failures reported? It seems the main issue is only the RMS or IMS but mostly the former. In any case it's at the gearbox or torque end of the engine. So it is feasible that the gearbox could be the cause or at least the area where the transfer of power to it is affected. You also have to take into account the service history of the car. If it's been maintained correcty by the Porsche dealership using Porsche approved parts and procedures then there should be no reason that the mechanics of the car should fail in this manner. Especially in an engine of this calibre and at such low mileage as is seen so often vis my car's 1st RMS was at 27,000 miles....and so ws the gearbox. Finally you also have to take into consideration the survey's that PCGB are conducting. The Boxster survey already shows clearly that the RMS failure is all too common. I feel certain the 996 survey will say same. I am particularly interested also in the rate of engine failures in the 996 and its relation to the RMS. But we will have to wait and see the outcome.
So, in summary, they are "the" best car to drive. But take it from me, they are mechanically flawed and unless you have warranty, you better have a very big slush fund.
Hope this helps.
