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IMS failures on automatics?
Yea yea, I am casually looking for an AUTOMATIC boxster. (or a BMW z4) I know I won't have the same driving experience as a manual, but I haven't driven a manual in over a decade and my wife never has. Auto it is for us.
Are the automatics known to have the same IMS failures as the manuals? Autos are less likely to have had the IMS replaced because of no clutch changes I assume. So far, I have limited my search to 1997-1999 cars as I have read in several places that those have the less risky bearing. I am wondering if the IMS happens to be less of an issue on the automatics for some odd reason, allowing me to broaden my search criteria. |
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History and sanity check: Through the years, Porsche used one of two bearings; a double-row and a single row. Earlier 986 boxsters used the double-row, switching over mid-year to a single row in 2001. The advertised rate of failure for single-row bearings is 8% for cars over 90K miles, but that number seems to come from guess who? The folks who have made tens of millions on a solution. Dual Row has a statistically lower failure rate, estimated at around 1%. That said, statistics don't mean much to you if your bearing fails, right? If your research leads you to worry about this, then for your peace of mind replace the bearing or buying a car that the previous owner addressed the issue in. IMHO, the best-advertised solutions out there are over-hyped and ridiculously overpriced. It's a bearing and it is easy to remove and replace the transmission, a little time and common sense or experience, but if you dont work on the car yourself, this is gonna cost you some cash. I chose peace of mind. |
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If you are not going to replace the facotory IMS, it is all an amount of your risk tolerance. |
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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? |
I say buy it drive it and have some fun don't worry about some dang bearing that's been way oversold. All things mechanical have a weak point. Every chain has a weakest link. For what you can buy these cars for and the value fun factor you receive its a bargain. That said I made enough in the market today to buy 2 more. We may not all be in the same boat
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https://www.europeanpartssolution.com/ims-bearing-upgrade-kit In case it gets censored: europeanpartssolution dot com I've never tried it, nor have I seen any feedback on it from anyone who has direct experience with it. |
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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. |
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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. |
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The pelican is the same as factory bearing, but a single-row, yes? I believe we cannot source the double-row bearing (or single row, but why would you?) directly from Porsche, the part number doesnt show in any of my parts drawings. RND has the single to double-row upgrade for 550 bucks, but only for cars withe the single-row. What is out there for double row replacements at a similar price point? EPS is a strong candidate but seems dependant on oil pump modifications. |
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On the other hand what I like about the IMS Solution is that there are none moving parts and the oil is feed directly from the oil filter (similar as the design used on the Metzger air cooled engines) . |
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LN has a dual row ceramic hybrid that they designed to work in the single row shaft. I have never cared for the roller bearing approach for several reasons, one of the biggest it the idea of using a pointed punch to wack a precision opening from the oil pump into the IMS shaft; second, I do not like the idea of purposely running a flooded shaft (the IMS Solution uses a plug pressed in behind the bearing specifically to prevent flooding the shaft. That roller bearing kit also uses a oil pump drive shaft with a grove cut in it to allow the oil to pass, the oil pump drive shaft is already a weak point in these engines, and they are weakening it even more. I like to replace the weak OEM shaft with a chrome moly steel aftermarket part that is way stronger than factory. |
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The reason the shaft is full of oil during an extraction is because the seals have hardened and shrunk, allowing the oil to get into the shaft. The fact that the oil found during an extraction is usually rancid is because it has been in there for some time because it cannot drain out when the level in the sump rises after the engine shuts down. As for oil mist not lubricating the bearing, every LN IMS restrofit (now over some 25,000) except the Solution depends upon the mist to keep the hybrid ceramics lubricated and cooled, And having extracted a few LN bearings over the years, there was no oil to speak of trapped in the shafts. |
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Plus having an open bearing, it would allow any oil that would get into the shaft to drain out. Did I get that right? |
The IMS bearing is only submerged in oil when the engine is not running and all of the oil has drained into the sump, assuming normal oil fill levels.
With all my respect, I don`t understand the logic behind that. Why would that be? At max level on the dipstick, oil level is close to the top of the shaft. Why would the oil level change so drastically when the engine is running? And if it changes, by how much? A liter? That would mean that one third of the shaft is still submerged in oil. When the engine stops, most of the oil that has been circulating will not flow back to the sump but will stay in the oil galleries, otherwise the proper and immediate oil pressure in the crank bearings could not be ensured right after start up. And we are talking about at least a liter of oil that should disappear upon engine start. Where? Once running, only a mist of oil kicked up by the crank surrounds the bearings while the engine runs. Has anybody looked at that experimentally? I read this statement everywhere but I still don`t get what it`s based on. The reason the shaft is full of oil during an extraction is because the seals have hardened and shrunk, allowing the oil to get into the shaft. The fact that the oil found during an extraction is usually rancid is because it has been in there for some time because it cannot drain out when the level in the sump rises after the engine shuts down. Yes, that`s one reason, the other is that pressure builds up in the shaft due to the rise in temperature, which then forces air through the seals, which then builds up vacuum in the shaft when the engine cools down, and oil seeps back to the shaft through the seals. After a few hundred cycles the shaft will be filled with oil. And having extracted a few LN bearings over the years, there was no oil to speak of trapped in the shafts. Yes, those are not sealed bearings so I assume oil just drains off the shaft when you drain the oil from the sump. I agree, removing the seals is a good idea, I still don`t understand why the Germans placed sealed bearings there in the first place and never changed that over the years. |
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How much oil is up in the engine internals when the engine is running? The answer is quite a bit of it, so much in fact that Porsche used scavenging pumps in the cylinder heads to help get the oil back to the sump faster to prevent the oil pump from cavetating and creating oil foam, which neither cools or lubricates properly. On the early cars with dipsticks, people often ask if it is correct to not have oil showing on the dipsticks with the engine running, and many have commented that the digital oil level indicators show the same thing right after the engine is turned off. There is a lot of oil entrained in these engines when they are running, a lot of it because of the “flat” configuration of the cases . At any given time, more than half of the entire oil capacity is up in the engine, when it is pushed, there will be even more. Oil mist inside the engine: Raby and LN examined this phenomenon during the development of the first generation of retrofits because they were concerned about how to properly lubricate the hybrid bearings. The rapidly turning crank and rods creates a huge amount of splash, and the rotating assembly is actually surrounded by a cloud of rapidly spinning liquid oil which creates the mist. Any racer worth their salt has had to deal with oil “windage” around the rotating assembly, and how to reduce it as it is actually eating horsepower. These studies led to a variety of ways to try and reduce this phenomenon by knife edging crank counter weights, windage trays, and even “scraper assemblies to try and divert the oil away from the rotating assembly to recover the HP lost to all the oil splashing around. The ultimate answer to controlling this is a dry sump system like those used in the Mezger turbo and Porsche race engines. IMS shafts with LN bearings not being full of oil: The LN bearing is open on one side (towards the flywheel) to allow oiling. The shaft side is still sealed. The use of better seal material and leaving one side open dramatically reduces the tendency of the oil to migrate to the shaft and remain there. As noted earlier, a lot of these shaft unit do not run true, so allowing (or forcing) oil in to the shaft can lead to significant imbalance loads on whatever bearing is in the shaft. Some racers have gone as far as to drill holes into the shaft to let the oil out; LN took a better approach: Don’t let it get in in the first place. Because the IMS Solution brings oil into the solid bearing at whatever pressure the oil pump is generating, which would quickly flood the shaft, Raby designed the system to use a freeze plug like seal that is hammered into the shaft before the Solution it inserted to permanently seal the shaft from oil intrusion. A simple, but very effective solution to the problem. |
How much oil is up in the engine internals when the engine is running? The answer is quite a bit of it, so much in fact that Porsche used scavenging pumps in the cylinder heads to help get the oil back to the sump faster to prevent the oil pump from cavetating and creating oil foam, which neither cools or lubricates properly. On the early cars with dipsticks, people often ask if it is correct to not have oil showing on the dipsticks with the engine running, and many have commented that the digital oil level indicators show the same thing right after the engine is turned off. There is a lot of oil entrained in these engines when they are running, a lot of it because of the “flat” configuration of the cases .
Exactly. There`s a lot of oil in the cylinder heads that is constantly being pumped back to the sump. As a result, when the engine starts, the scavanging kicks in too, so the oil level should be even higher in the sump than when it`s shut off... I still don`t get it. About the dipstick: how could the level be measured when the engine is on while oil is being splashed all over inside the engine case including the dipstick? Oil mist inside the engine: Raby and LN examined this phenomenon during the development of the first generation of retrofits because they were concerned about how to properly lubricate the hybrid bearings. Interesting, I`d like to read more about this, is this published somewhere? How did they do it? They inserted a boroscope into the case? |
The oil isn't just in the heads when the engine is running. Think of the oil pump, the cooler, and all the oil passages throughout the engine. All of those add up to a fair amount of oil being in the engine, and not the sump.
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The dipstick will show spots of oil when the engine is running, not a wet level. If your hypothesis was the case, why do most people that race these engines both improve the baffling in the sump and deepen the sump, or move to a true dry sump it the rules allow? Because the low level of oil remaining in the sump can easily slosh to the side and uncover the oil pickup leading to pressure loss, oil starvation and some rather unfortunate damage. The oil level remaining in the sump on a running M96 is MUCH LOWER than you think. The number one lubrication modification when seriously racing any engine is to CONTROL oil movement within the engine. Normally this. Is accomplished by literally jetting certain oil passages to limit the amount of oil going to places that don’t need much oil volume and cleaning up the passages to help get the oil to critical components like the rod and main bearings. Some GM engines that normally carry 7 quarts of oil in the sump can get as low as 1 1/2 to 2 quarts when the engines pass 4-5K RPM because most of the oil is up in the heads; putting jets into certain oil passages cuts the oil trapped up top to 1-2 quarts, and this is in a nearly vertical v8 design engine case where gravity is your friend when it comes to getting the oil back to to the sump. Porsche’s cases are horizontal, and drain back by just gravity is not sufficient to get the oil back down to the sump, hence the scavenger pumps, and still most of the oil is still not in the sump, but up in the engine. |
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Thanks, I really appreciate that you gave a slight chance to the possibilty that my hypothesis might have some relation to reality :o In normal conditions the oil mass is not sloshing too much, in race cars it may be, so baffling makes sense there. And so does deepening the sump, providing more oil that can be chilled more effectively. These are useful features in racing, but that doesn`t necessarily mean that these features have anything to do with the oil level or the IMS bearing`s lubrication. I was talking about normal operational conditions though. And I still don`t get where would about 1-2 quarts of oil go when you just simply turn on the engine. I also have difficulties in understanding how can it be claimed for sure that the IMS is lubricated by oil mist. To safely say that, you would need to insert a glass window into an engine case to see the oil level, or directly onto the IMS flange, so you can see the bearing during operation. Or you could fit a small boroscope there, but how would you do that? Once you turn off the engine, the putative window or camera would be overwhelmed by oil. It`s not a trivial experiment to do. That`s why it would be great to know where this whole oil mist theory coming from. The GM engines cannot be compared to flat engines in this regard, because as you pointed out, in a flat engine much of the oil coming out from the heads (which is still nowhere near to 1-2 quarts because of the small orifices that won`t let the oil warm up too much in the relatively hot heads) will not return to the sump because the scavanging pumps are not running. |
It is actually very easy to determine how much the oil level drops in any style engine: You build a simple sight glass level tube using flexible clear plastic tubing connected to a barb fitting in the sump cover, and the other end run up the side of the engine case and connected to the cam cover. Add oil one liter at a time and you can index mark the levels on the tube with tape or a marker. We did this all the time while running engines on a dyno to watch what level the oil dropped to at different RPM’s in order to make sure it stays away from the crank for windage control, but deep enough to keep the wet sump oil pump pickup covered. That is how I know an LS engine can drop to two quarts left in the pan at 5kRPM, and that the IMS bearing is not in the oil on an M96 engine when it is running.
So yes, you can acutally check the water level in a running washing machine if you put your mind to it. Have a good evening.............. |
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I see I sparked quite the discussion! This forum is full of incredible knowledge, thank you for all of the responses.
It seems that there are a couple bearing replacement options for single-row cars? The IMS issue has kept me from considering cars with the single row, however, maybe I should consider these while including the cost for bearing replacement. I plan to do basic wrenching on the car, but with little mechanical experience, an IMS change is beyond my capacity. How much would I need to budget in to have the IMS changed to the best solution by an Indy? (automatic car) |
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Many people on here believe that the LN "IMS solution" is the best one. But it comes at a very steep price just for the parts. So much so that at $1849.00, parts alone cost over half as much as a used motor. So, you'd have to decide for yourself whether you're comfortable with the cost v. risk ratio. I have a tiptronic, single row IMS. IF, and that's a big if, I decide to replace it, I'd probably go with an OEM replacement. Although I'm still curious about the cylindrical bearing. But that's my decision, you'd have to decide which replacement is best for you. This guy makes a very good argument, even though he came to a slightly different conclusion than I did: https://www.youtube.com/watch?v=IxdvSq_byZw |
Aren't the ball bearing IMSs oiled at rest by what is in the sump and once running by an oil mist in the crankcase whipped up by the rods and crank. Doesn't that imply a drop in the crankcase oil level once running.
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And the skills to make those custom parts he speaks of? We all have those.
There are at least 5 other IMS replacement offerings I know of he didn't mention. All with varying characteristics. The investment to create a bearing assembly, test it, create tools and instructions that facilitate it being done by someone who never has done it before are worth something. To say nothing of warranty expenses and customer service costs. Maybe not to the video producer. I happened to be in touch with the guys who first created the replacement kits when they were destroying bearings and engines in their quest for the right one. They were a long time recovering those sunk costs. I've owned 2 Boxsters. One a dual row, one a single. I totaled the first car without having replaced the IMS. Someone got a low mileage engine probably when the insurance company totaled the car. I didn't replace the second one, it was still in the car at 90k last I heard. What is your risk tolerance? How would you feel having replaced the bearing assembly and something else takes out the engine or car? How would you feel if the bearing failed and you hadn't replaced the assembly? How long do you think you will keep the car? A great replacement will add value but not the total cost of the replacement. A good replacement will help sell the car quicker. If I were to replace, I'd go great or at least with one that had many thousand known installs. |
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Burner is cool. I’ve wondered what happened to him. If Anyone knows, please share and my hellos to him. So, yes, if you replace I think there are a few options, but the safe option is LN. I still balk at the price and I refuse to believe it’s fair, but so goes. I will concede that with the pricing for various LN offerings, Saving between 500-1600 dollars on the part is more than tempting to consider less expensive options. Sent from my iPhone using Tapatalk |
Hi
People keep talking about an "OEM" bearing. What exactly would that be? NSK 6204 with seals? Would it be a C3 clearance or standard? Thanks Berni |
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NSK BD20-17 6204DUA17 |
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Thank you But can you actually buy either of those two bearings off the shelf now? I read that the dual row is totally NLA, and when I was hunting around could not find a 6204DUA17 unless it was from Pelican with the kit. All the best Berni |
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https://www.123bearing.com/bearing-BD20-17-A-DDUA17NX01-NSK.php |
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