IMS failures on automatics?

[Gilles]

Originally Posted by tonythetiger

EPS is a strong candidate but seems dependant on oil pump modifications.

Tony, one of the reasons why I don't believe that the idea behind the EPS design is a good one, it's because it will fill up the IMS shaft with oil withe the possibility of creating other unwanted side effects like an unbalanced shaft, unwanted inertia perhaps..? However, I am Not an engineer... so please take my comments like a grain of salt.

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)
.

[Homeoboxter]

Originally Posted by Gilles

Tony, one of the reasons why I don't believe that the idea behind the EPS design is a good one, it's because it will fill up the IMS shaft with oil withe the possibility of creating other unwanted side effects like an unbalanced shaft, unwanted inertia perhaps..? However, I am Not an engineer... so please take my comments like a grain of salt.

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)
.

It`s a common misconception that the IMSB is running dry and it`s lubricated only by oil mist, therefore some extra oil pressure through the shaft is going to solve all the IMS problems. The IMS is submerged in oil. (Let`s disregard now the seals on the bearing and the original grease pack that probably lasted a few weeks after the first owner started using the car). That`s why everyone who removes the IMS bearing in situ, reports about a quart of oil flowing out from the shaft. So adding an additional oil pressure line into the shaft won`t hurt, but it`s not necessary either. Even EPS claims that on their website, that oil lubrication is completely unnecessary, they just throw it in, because otherwise people would not be convinced it`ll work.

[JFP in PA]

Originally Posted by Homeoboxter

It`s a common misconception that the IMSB is running dry and it`s lubricated only by oil mist, therefore some extra oil pressure through the shaft is going to solve all the IMS problems. The IMS is submerged in oil. (Let`s disregard now the seals on the bearing and the original grease pack that probably lasted a few weeks after the first owner started using the car). That`s why everyone who removes the IMS bearing in situ, reports about a quart of oil flowing out from the shaft. So adding an additional oil pressure line into the shaft won`t hurt, but it`s not necessary either. Even EPS claims that on their website, that oil lubrication is completely unnecessary, they just throw it in, because otherwise people would not be convinced it`ll work.

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. Once running, only a mist of oil kicked up by the crank surrounds the bearings while the engine runs.

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.

[piper6909]

Originally Posted by JFP in PA

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. Once running, only a mist of oil kicked up by the crank surrounds the bearings while the engine runs.

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.

So, if one just pulls the seals off an OEM bearing it'll get an oil mist, the same mist the ceramic bearing would get, right?

Plus having an open bearing, it would allow any oil that would get into the shaft to drain out. Did I get that right?

[JFP in PA]

Originally Posted by piper6909

So, if one just pulls the seals off an OEM bearing it'll get an oil mist, the same mist the ceramic bearing would get, right?

Plus having an open bearing, it would allow any oil that would get into the shaft to drain out. Did I get that right?

Basically.

[Homeoboxter]

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.

[JFP in PA]

Originally Posted by Homeoboxter

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.

OK, let’s take this in the order you posted:

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.

[Homeoboxter]

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?