What is Rear Main Seal

Did a search, and found some alarming news about Rear Main Seal. Mostly from this thread. http://www.planet-9.com/showthread.php?t=7940&highlight=rear+main+seal 1,486 miles into my new car, I found a small gathering of engine oil on my garage floor, and the "check engine" light came on. Took it in for service today, and the service tech told me that they replaced an "Rear Main Seal ", which I thought was not a big deal. But reading the above threat, there seems to be some concerns about a car losing value b/c of such a replacement. Is it a big job? What exactly is it? Could it possibly cause the "check engine" light to come on?? (I thought the "check engine" light is mostly exhaust/emission related) Thanks Randy

RMS covers an umbrella of problems related to the M96 engine block which has powered all non- GT3 /Turbo Porsches since 1997/98. Oil leaks can occur from a variety of locations which are not just confined to the Rear Main Seal. I had a couple of "RMS" leaks on my 986 Boxster fixed under warranty which never returned. Most oil leaks are not "fatal" to the engine and are easily fixed. There is a crankcase/crankshaft problem that can result in an engine replacement from Porsche , some of which were actually done out of warranty for some 986 owners as I recall. I'm sure there will be more detailed explanations to follow this. Basically I wouldn't be too concerned, as most of the early problems have been fixed and I believe that Porsche will step up to the plate for anything major. I would say that any oil leaks noted should be diagnosed ASAP and not put on hold.

Dave is correct in his capsule history of RMS problems. As he said, the techs tend to lump quite a few things under the RMS diagnosis. I had an RMS failure with my 1999 996 - it was fixed and never returned. I know the people who currently have the car and it's fine and has 53k miles on it. If this is indeed an RMS leak, it will be one of a very few reported on the 9897 or 997 cars to date. I don't think you should be alarmed unnecessarily. Nor should you worry that the value of your car will be diminished. It's just not that big a deal, really. A number of things can trigger the "check engine" light, not just emissions problems, although those seem to be the ones that set it off the most. I also doubt an oil leak will trigger the light on it's own. brad

the official invoice states Check Fluid Leak from Vehicle 15 -- Check out and Replace Leaking Rear Main Seal 997-101-212-00 Shaft Sealing ring ........ x1 999-073-092-09 Screw 10x50 .............. x8 -- 1470 Rear Main Leaking/Twisted, Replaced and Cleaned 34351903/13591950/34352950/10012900 6.9 Check Engine Light On 15 -- Perform Check Out and Smoke Test -- 1470 P2187/2189 Intake Leak Found Ant. Rear Crank Seal, Repaired with Repairs on Line #1 03350000/03350050/24460100 1.30 1468 I have no idea what any of those means. Hope it fixed the problem though

BTW, the Porsche Genuine Parts Catalogue for the 987C Cayman lists the engine type for both Cayman models as M97.

RChang -- Not clear what was really done at the dealer. Your post made it sound like it was a one day service call. The engine rear main seal replacement ought to be a bigger deal. I would guess the P-car is no different than others, in that the RMS is at the rear of the crankcase, ahead of the flywheel. So the transmission, clutch, and flywheel have to come off, at a minimum. I have no knowlege of what has to be done on our engines to remove and replace the seal itself, but the whole process is time-consuming, i.e. expensive.

Decoding AKA the rear main seal The dual-mass flywheel attachment bolts I think those ODB-II codes indicate that a lean condition at idle speed on both sides (banks 1 & 2) of the engine has been detected. Looks like they decided that the faulty seal was not only letting oil leak out of the engine, but was also letting air leak in.

Fast Croc - good analysis - RChang - I think the problem was a badly installed rear crank gasket which was installed twisted when the motor was put together, and was leaking. They've cleaned it all and replaced it. On my RMS repair, back in '99, once they got the gasket from Germany, the repair took one day. Keep an eye on it, but I'll bet this has been fixed. Yes, a leaky rear crank seal, but not really the dreaded RMS problem. brad

AgCroc um...... dropped the car off at 11:00am, and they called me at 4:00 telling me it was done already!! Maybe they stopped everything at the service bay and put all their manpower on my car in order to crank it out faster??? I honestly have no idea, but I WILL keep a close eye on my garage floor for the next couple of days..... Thanks for the info

question Have you thought about asking the dealership for an explanation of exactly what they did? And also ask them about how serious it was? Ask to talk to a mechanic, not just one of the service desk reps. They should be more than willing to let someone talk to you and give you a complete run-down of what they did.

Is this the dreaded RMS leak? Here's a little info for those who might see oil leaking from a Cayman's M97 engine and ask themselves the question: Is this the dreaded RMS leak? BTW, the probability that a RMS (aka Shaft Sealing ring ) would leak enough air into the engine to trigger OBD-II faults is greater if it's torn instead of just worn.

I have an '01 Boxster 2.7. When it was about 3 1/2 years old, with under 5,000 miles, I started to suspect a problem. The RMS was eventually replaced. Is it the case that nothing has been or can be done by Porsche to correct this problem? I have not had a recurrence (no visible leaks), but I would hate to have the sword of Damocles hanging over me as I attempt to enjoy my new Cayman (which will be built one week from today). It is making me queasy just thinking about the possibility of having this problem again. When I first suspected a problem, I complained to the service manager about an odor upon exiting the car. He chalked it up to extremely cold weather. When the car was just about at the end of the warranty period, I insisted that they check it out, and that is when the RMS problem was diagnosed and fixed. I am in desperate need of reassurance! Thanks to anyone who can ease my mind a bit. 987f

987f wish I can provide you the reassurance you are looking for, but my car seems to be an isolated incident where the seal is twisted...?? I can, however, tell you that my garage floor did not contain a drop of engine oil this morning after having it services yesterday. Maybe someone else with more knowledge can shed more insight on whether Porsche has addressed this lingering issue from the Boxter owners in the Cayman

987f - Well, I'm not sure what will reassure you, but here's what I know, based on personal experience with the problem, and reading from sources such as the PCA tech Q&A and personal conversations with three different PCA tech forum experts that I know. The motors are still made the same way - the crankshaft sits in a cradle that is separate from the crankcase itself, and the cradle sits down in the actual crankcase. Most of the time, it's on-center. Sometimes the casting process leaves the cradle slightly (and I mean very slightly) off-center. Most of the time, it's not a big deal. Sometimes it is more off-center, and then it becomes a big deal - the seal will break down and leak. When the car is brought to the dealer's service dept. it's diagnosed, and if RMS is suspected, they take it apart and use what's called a "go/no-go" gauge. It's essentially a gauge that they slip on to see how off-center things are. If they're within the tolerances of the gauge, then they fix it with a new seal. They're now using a seal/gasket that is made of sturdy Teflon (they're white, I'm told) and is derived from the rear main seal in the Cayenne V8 motors. From everything I've read and been told, these new gaskets do the trick, and there are few, if any re-repairs when it is used. If they use the gauge, and the off-center is more than the gauge allows, then they replace the motor with a new crate motor from the factory. They also issue you a statement showing that the motor was installed, what the serial number of the new motor is, and the factory changes it records (there's some contention on this last bit as to whether or not they actually do this) to reflect the new association of that motor's serial number with the VIN of your car. You still allegedly have a "numbers matching" car, so to speak. There is no real anecdotal evidence that putting a new factory crate motor decreases the value of your car. As I mentioned above, I had an RMS leak on my '99 996, and it was fixed long before this new gasket/seal came about - which has been just in the last year or so, and the dealers have to provide the factory with a car's VIN and RMS diagnosis in order to get one of the new seals. It has stayed fixed, too. I too, had apprehensions about the RMS - so much so that it was part of my decision to buy a 996 turbo (which uses the old style - aircooled cars' split crankcase motor with water-cooled heads, as does the GT2 and GT3 ) which does not have the RMS problem. I'd also always wanted a turbo, and who could argue that the 996 turbo wasn't a car to have back in 2002? But, it was only part of my decision to get the turbo - the biggest one was the grin on my face when pushing down hard on the gas pedal. When deciding to get the Cayman as a replacement for the turbo, I did consider the RMS problem as a possible factor, which is why I did all this reserach on the problem, but with the advent of the new repair procedures, and what I've been told has been better casting work for the crankcases at the factory, I decided to take the plunge back into the M97 motor world. I think that these factors have been borne-out in that much fewer RMS problems seem to have happened to the 987/997 line of cars, although they are not unheard of. The problems usually crop up, if they do at all at around 16k-25k miles, well within the warranty window. The only problem with that is if you have a very low mileage car, that goes out of warranty because of time. As an aside, the 986 /996 cars with Tiptronics have an extra brace for the transmissions, which apparently help in this regard,, and the RMS problem is very, very rare on cars equipped with Tip transmissions. The same design has carried over to the 997/987 cars with the Tiptronic. They've come a long ways since your '01 2.7 Boxster imo, and that's why I bought the Cayman S . Sorry for the long post. brad

Randy, glad to hear that your garage floor is dry, and hope that your problems are all in the past. Beez, your explanation was not only highly informative, but went a long way in providing the reassurance that I truly want. I asked my service manager what would happen if the problem recurred after expiration of the warranty period on the Boxster . He said that Porsche would stand behind the initial RMS repair. I hope that he knew what he was talking about. In any case, it sounds as though, between better casting quality control and the new seal material, Porsche does indeed have a handle on things. It's at times like these that I am thankful for such a treasure trove of collective wisdom and technical information. I'm very glad to have joined this forum before buying my Cayman ! :burnout: :cheers: 987f

Uh-oh The parts catalog indicates that the seal that should have been installed when the engine in that '07 Cayman was built has the same number (997 101 212 00) as the part which was installed during the repair. This report (a low-mileage failure of what should have been the latest and greatest version of that part) leads me to wonder if that work is good enough. Too bad we don't know how many of these problems have been heard of only by Porsche. Uh-oh. My plan is to drive it less than 5k miles a year, which wouldn't get thru that range before the four year deadline.

Yes - what this person is calling a "carrier," I'm calling a "cradle" above - basically the same explanation. For quite a while with the 996/ 986 cars, the dealerships did not have the "go/no-go" gauge, and they were trying to repair cars that really needed a motor swap, so there was a lot of re-repairs. FWIW, I decided when I bought the Cayman S , that a) it's not such a prevalent problem as it once was... b) I survived it with the 996 back in 1998 c) there's a good warranty in place, and d) because of all that, I'm not going to lose any sleep over it. YMMV. brad

Thanks.... looks like I'll get a good night sleep tonight too

On the contrary. I hope mine blows a leak at about 40,000 miles which requires a new crate motor..... In my opinion, a car with a new motor is worth more than one with a used motor. Looks like a change in plans is needed. Might I suggest driving it 12,000 miles a year.....?

Seal Issue and gaskets When going over the Boxster boards some time ago, one person stated that the newly designed seals were used after May of '05. I think the build date was May 17, 2005. In any event, the rate of failures is much lower on the 987 then the 986 which, may indicate that this fix did occur about that time. When buying used, the post stated to look for a build after May or 05. However, the fix is an easy one that Porsche has been willing to fix. This information came up on a survey that was done on Pete's Boxster Board by Lauren. They tried to come up with a valid info base for what failures had occured over what model years. As we know, Porsche is not willing to discuss these issues but the initial study on Pete's board was informative.

Engine Failure Survey I found a thread on Pete's Boxster Board that has a link to the results of the survey conducted by LorenS: BOXSTER FAILURE SURVEY RESULTS (yes, it really is in all caps.). Wikipedia's Boxster article notes that: While the Cayman uses the derivative M97 engine, both types support the crankshaft and crankshaft seals the same atypical way; separately. The crank is supported by a bearing box (which the English and German parts catalogs label as Gear Carrier and Lagergehause , respectively) and the crankcase supports the seals. Selected results from the survey published by LorenS in January, 2007: Information about the data collection by LorenS can be gleaned from the survey form . BTW, there's also a ******** discussion thread about the survey by LorenS , and a RMS Mystery Solved thread that began on March 26, 2006:

Fast Croc - I guess I'm wondering what your point is here... This survey, while well meaning, is so unscientific as to be laughable. It shows that a certain high percentage of 255 Boxster owners who also are members of two Internet chat forums who cared enough to answer a survey had an RMS problem. As they said, "if a major Detroit label had numbers that high, it would make the news." I dare say that if the actual numbers of RMS problems occurring to all owners were that high, it would have made the news, too... but it didn't, and nowhere near that percentage of all late-model Porsche owners experienced an RMS failure. Porsche would be out of business if that had occurred. Sorry, but whatever hoo-ha people are trying to make of this, it just isn't that big a problem, and I don't think it's something anyone should really be alarmed about at this point. If one wants to use anecdotal evidence as science, then judging from what people have reported on the Cayman Club, there's been way more Cayman owners with loose pressure plate bolts than RMS leaks. brad

Brad - I agree. I'm not certain what the threshold of failures is to warrant a recall, but if the 51% of RMS failures reported in the survey were accurate nation wide, then I believe Porsche woul have had to initiate a recall. A couple of years ago I checked with some friends who worked at two Porsche Dealers near to me, and they both indicated that about 25% of the 996s that they serviced had RMS leaks. They also told me that after the seal was replaced less than 10% returned for another seal replacement, and this was even before the new seal was available. Bottom line is that if there is a seal defect, it's very likely that the defect will become apparent well before the warranty has expired.

Oil leak Something fishy here. If you report a problem during warranty and they finally decide it's a problem after, they're still responsible because the problem occurred during the warranty period. Unless they're claiming it's a different leak, something just doesn't sound right. But who knows what the real story is.

I was wondering when the LorenS data would surface here. The survey is obviously biased, by that I mean statistically, in that it only represents self reporting of a self selected group, but not entirely without value. The numbers of problems trend toward highest in the early model years (97-99) but do not completely disappear suggesting that most but not all problems have been fixed, most notably the porous engine block castings in 1997, or at least ameliorated. The data cannot be used to determine the true magnitude of the problem (incidence or prevalence) because of the very limited sample size and self reporting. "RMS" problems should not be a major factor in the decision to buy a 987 or 997 series Porsche w/ the M96 derived M97 motor .

More Help Needed 1 week after getting my "twisted" Rear Main Seal fixed, I found a very very small puddle of engine oil on my garage floor again. Should I be alarmed? could it be residual drippage? Take it in for service again????

Hmmmmm, bummer. There shouldn't be any residual dripping assuming they cleaned the whole thing up when they repaired it the last time... I don't think you should be necessarily alarmed (10" puddle of oil on the garage floor...? then you should be alarmed) but since what you describe is a very, very small puddle, not a couple of drops, you should take it back and ask them to fix it so there's no leaks. brad

There should be no residual oil after the repair. As Brad pointed out, the area is cleaned during the repair. Unfortunately seals either leak or don't leak, and small leaks will do nothing but get progessively worse. If i were you I'd make absolutely certain that the garage area is completely free of oil. Let's hope that the oil you saw is from your prior leak. Otherwise, take it back to the Dealer.

Revolutionary design? I'm not sure that it's really an RMS problem, given the following opinion of an automotive engineer : Notes: The 996 used the M96 engine. The 997 S uses the M97/01 engine. Caymans use the M97/20 or M97/21 engine.