IMS failures on automatics?

[norcalconvertible]

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.

[JFP in PA]

Originally Posted by norcalconvertible

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.

IMS failures are common on all M96/97 engined cars, regardless of transmission type. And just as a reference, the dual row IMS was used up until the 2001 model year, but 2001 cars could go either way. And before you ask, no, there is no known way to positively identify which 2001 engines had it and which were single rows; you have to pull the car apart and look.

[tonythetiger]

Originally Posted by JFP in PA

IMS failures are common on all M96/97 engined cars, regardless of transmission type. And just as a reference, the dual row IMS was used up until the 2001 model year, but 2001 cars could go either way. And before you ask, no, there is no known way to positively identify which 2001 engines had it and which were single rows; you have to pull the car apart and look.

All true, except to call the IMS failure "common" feeds into the fearmongering of the IMS issue. I do agree its a concern. FWIW, I am on my 4th 986 and never had an issue, even replacing IMS on 3 of them. Every bearing I removed looked perfect. (2 dual row and a single) I also don't know anyone that has personally suffered a loss.
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.

[JFP in PA]

Originally Posted by tonythetiger

All true, except to call the IMS failure "common" feeds into the fearmongering of the IMS issue. I do agree its a concern. FWIW, I am on my 4th 986 and never had an issue, even replacing IMS on 3 of them. Every bearing I removed looked perfect. (2 dual row and a single) I also don't know anyone that has personally suffered a loss.
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.

Porsche’s last published data showed 12.6% failures for single rows, 3%+ for dual rows, and that data is now several years old, so there have probably been more in the intervening time. Porsche also produced a third design (2005-2008), the non serviceable unit because of its size, and the last rate of failures on that design was 1-2%. So, in essence, all versions failed, just a differing rates. To my knowledge, there is no viable correlation between mileage and rates of failure; we saw them die in cars with less than 10K miles, and well over 130K miles.

If you are not going to replace the facotory IMS, it is all an amount of your risk tolerance.

[tonythetiger]

Originally Posted by JFP in PA

Porsche’s last published data showed 12.6% failures for single rows, 3%+ for dual rows, and that data is now several years old, so there have probably been more in the intervening time.

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?

[MrBen]

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

[piper6909]

Originally Posted by tonythetiger

... 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've been curious about this one:

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.

[JFP in PA]

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?

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.

[Racer Boy]

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.

[Homeoboxter]

Originally Posted by Racer Boy

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.

True. But it`s a closed system. The oil that circulates will not flow back to the sump when the engine is off, or at least most of it remains in the oil lines, cooler, pump, etc. If this wasn`t the case, the main bearings would be starving of oil at every start up and they would fail shortly. When you pull apart an engine, especially a boxster, oil is flowing out from every oil channel and gallery producing a huge mess on your garage floor, even though you already drained the sump. When the oil pump gears are not rotating they seal off and won`t let the oil flow back to the sump. As a result, oil level should not change much during engine run vs stop, IMHO.

[JFP in PA]

Originally Posted by Homeoboxter

True. But it`s a closed system. The oil that circulates will not flow back to the sump when the engine is off, or at least most of it remains in the oil lines, cooler, pump, etc. If this wasn`t the case, the main bearings would be starving of oil at every start up and they would fail shortly. When you pull apart an engine, especially a boxster, oil is flowing out from every oil channel and gallery producing a huge mess on your garage floor, even though you already drained the sump. When the oil pump gears are not rotating they seal off and won`t let the oil flow back to the sump. As a result, oil level should not change much during engine run vs stop, IMHO.

Which fails to explain why 5 min. or more is needed before the digital oil level gauge reads correctly on a hot M96.

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.

[Homeoboxter]

Originally Posted by JFP in PA

Which fails to explain why 5 min. or more is needed before the digital oil level gauge reads correctly on a hot M96.

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.

I don`t understand how it makes sense to say anything about oil level in a running engine using either a dipstick or a level sensor. The IMS, the sprocket and the chain are all spinning in the oil, splashing oil everywhere in the case. Itt`s like determining precisely the water level in a running washing machine with a stick. Good luck with that.

Thanks, I really appreciate that you gave a slight chance to the possibilty that my hypothesis might have some relation to reality

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.

[BYprodriver]

Originally Posted by Racer Boy

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.

At high rpm's alot of the oil is in the heads waiting for the scavenge pumps to send oil back to the sump. That's the reason when you check oil level it can vary alot. If you drive at low rpm before you park or idle for half a minute before turning engine off, the oil level will show higher.

[JFP in PA]

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..............

[Homeoboxter]

Originally Posted by JFP in PA

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..............

Ok, that makes sense, so something similar to the way you`d measure the float level in a carburetor, if I understand correctly. Sorry, if I went too far with all these questions, or with questioning the status quo, but I always try to go deep into something that`s unclear to better understand it, that`s my very nature. Thanks for taking the time by the way to answer my posts, I learnt a lot actually. All the best.

[mikefocke]

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.

[Homeoboxter]

Originally Posted by mikefocke

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.

Crank and the whole bearing carrier is lying much higher than the IMS, and the rods are sticking out sideways, if that makes sense, so they should not whip up the oil. At least not in my 2.5 engine.

[norcalconvertible]

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)

[piper6909]

Originally Posted by norcalconvertible

... How much would I need to budget in to have the IMS changed to the best solution by an Indy? (automatic car)

The key word in your question is "Best". Before anyone can answer that question for you, you first have to decide which bearing solution is "best" for you, as there are more than several options and as many opinions.

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

[mikefocke]

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.