It's finally my turn - RMS / IMS leak

[smak]

Just want to share the pictures of my 1999 C4 convertible RMS IMS.

If I am right, this seems to be a double roll bearing with minor leak from the RMS and possible some on IMS.  

Browsed online for the bearing and found way more choice on improved bearing than just LN Engineering.   

 

Anyone tried other improved version?  Roller type? Pelican part ( Cheapest)?

How bad is the leak?

 

thanks,

Simon

 

 

[JFP in PA]

Couple of points to ponder:  Roller bearings have no greater load carrying capacity than ball bearings, and are actually at a deficit above certain RPM levels.  Roller bearings tend to be less forgiving under slight misalignment, which is common in IMS shaft operation.  And while ceramic ball bearings can survive quite well on oil mist lubrication, the same cannot be said for roller bearings.  And because of possible patent infringement's, roller bearing IMS retrofits resort to rather questionable ways to attempt to lubricate them better.

 

The Pelican bearing is simply a new factory bearing, but with a very large caveat: They do not make a dual row version, which your engine is.  As the result, a Pelican would be a single row bearing with a spacer; so you would be replacing the strongest version of the factory IMS with the weakest version.

 

So at the end of the day, while their may be other choices than LN ceramic hybrid bearings, the simple fact that there are now more than 25,000 LN ceramic hybrids running in everyday use, the same cannot be said for the roller bearings.  I would suggest you read up a bit more on the different style systems before making a choice........

[dporto]

Considering all the work involved plus the cost of the tools (basically the same regardless of the bearing you use), it seems foolish to try to save $ on the bearing itself...

[dct911]

I just recently purchased a 996 4S and have been contemplating replacing the IMS immediately for peace of mind.  In searching for replacements, I've seen the LN Engineering ceramic version, but also ran across the IMS Direct Oil feed kits from TuneRS Motorsports.  Given the underlying reason they fail (long term lack of lubrication), a direct oil solution seems to be a very logical approach to solving the issue, vs trying to replace the bearing with something that will just last longer without proper lubrication.  Has anyone used the direct oiling solution as an alternative to ceramic bearings?  I'm completely new to the Porsche - so I have no expertise in this area so similar to the OP, want to know what options exist.  Less concerned about cost and more about durability.

[JFP in PA]

Welcome to RennTech 

 

The claim that lack lubrication is the only cause for IMS failures is a best suspect.  With the early cars all carrying dual row bearings, lack of lubrication should have been more of a problem for them as they have twice the number of ball bearings in motion; yet just the opposite happened: The dual rows have proven to be vastly more durable than the single row bearings that came later.  IMS failures are a much more complicated issue, with a variety of factors ranging from shaft wobble to materials of construction coming into play.  

 

The ceramic hybrid bearings LN uses only need a very low volume of oil from the mist inside the engine to lubricate properly; this is one of the reasons they designed this bearing this way to preclude the need for an outside oil source.  Adding additional oil, particularly coming from the cylinder heads, is actually detrimental to the ceramic hybrid's survival.  With more than 25,000 installations currently running on the streets, they would appear to have proven the design.

 

Oil coming from the cylinder head is also one of the hottest and dirtiest sources for oil, making this is a bad idea.  There have been multiple reports (we have had two in my shop alone) of both cylinder head noise issues as well as VarioCam problems when drawing an oil feed off the cylinder heads, both of which were solved by disconnecting the oil feed from the cylinder head source.

 

There are now a variety of "me too" retrofit kits available in the market, ranging from cheap OEM type bearing replacements, to roller bearings, and oil fed kits; but only the LN systems have been both tested to destruction before they were taken to market and have proven themselves on the street with massive numbers of successfully performing installations.

 

If your decision is based upon durability and life span over costs, take a close look at the LN IMS Solution, which is a solid bearing (no moving parts) design similar to the one used in the legendary air cooled turbo engines Porsche used to make. It uses an oil feed coming from the oil filter, so the oil is both clean and cool.  Like other LN products, this system has been tested to destruction, including prolonged running without an oil supply, and survived every time.  It is also the only retrofit that is a permanent life of the engine design.

[BufordTJustice]

Welcome to RennTech 
 
The claim that lack lubrication is the only cause for IMS failures is a best suspect.  With the early cars all carrying dual row bearings, lack of lubrication should have been more of a problem for them as they have twice the number of ball bearings in motion; yet just the opposite happened: The dual rows have proven to be vastly more durable than the single row bearings that came later.  IMS failures are a much more complicated issue, with a variety of factors ranging from shaft wobble to materials of construction coming into play.  
 
The ceramic hybrid bearings LN uses only need a very low volume of oil from the mist inside the engine to lubricate properly; this is one of the reasons they designed this bearing this way to preclude the need for an outside oil source.  Adding additional oil, particularly coming from the cylinder heads, is actually detrimental to the ceramic hybrid's survival.  With more than 25,000 installations currently running on the streets, they would appear to have proven the design.
 
Oil coming from the cylinder head is also one of the hottest and dirtiest sources for oil, making this is a bad idea.  There have been multiple reports (we have had two in my shop alone) of both cylinder head noise issues as well as VarioCam problems when drawing an oil feed off the cylinder heads, both of which were solved by disconnecting the oil feed from the cylinder head source.
 
There are now a variety of "me too" retrofit kits available in the market, ranging from cheap OEM type bearing replacements, to roller bearings, and oil fed kits; but only the LN systems have been both tested to destruction before they were taken to market and have proven themselves on the street with massive numbers of successfully performing installations.
 
If your decision is based upon durability and life span over costs, take a close look at the LN IMS Solution, which is a solid bearing (no moving parts) design similar to the one used in the legendary air cooled turbo engines Porsche used to make. It uses an oil feed coming from the oil filter, so the oil is both clean and cool.  Like other LN products, this system has been tested to destruction, including prolonged running without an oil supply, and survived every time.  It is also the only retrofit that is a permanent life of the engine design.

Being an IMS neophyte, my research has led me to the same conclusions, JFP. The causes for IMS bearing failure are much more varied than just bearing radial and axial load, oil supply/lubrication (or lack thereof), etc. I've recently fallen down the rabbit hole of shaft misalignment, shaft wobble, etc.

And, considering the overall cost of the labor (or time, if DIY), paying more to convert the rear of the bearing to the same as the front (a liquid, hydrodynamic bearing) starts making a lot more sense.

Especially when one doesn't have to pay labor to DO IT AGAIN in 60-75k or whenever the clutch needs to be serviced again.

That's where I'm at in my research. Not putting any non-LN solution down at all.

Sent from my SPH-L720T using Tapatalk

[dct911]

The LN engineering solution that's perm and uses an oil feed is the way I'm likely to go at this point.  I'm hard on my cars, and know I'll regret it if I don't go overboard making sure it won't fail on me.

[smak]

I finally replaced it with the NSK cylindrical bearing.  After ~500kms, not problem so far.  The original bearing was dual roll and they are still in great shape after 160K kms.

[rockhouse66]

23 hours ago, smak said:

I finally replaced it with the NSK cylindrical bearing.  After ~500kms, not problem so far.  The original bearing was dual roll and they are still in great shape after 160K kms.

I also went with the roller bearing. RND retrofit in my case.  Time will tell if we made a good decision, but I think a car with a lot of miles on it and the original IMS bearing will likely do fine with pretty much any new bearing you use.  The LN "Solution" is clearly the superior approach.  It was not well advertised (or, in my case, understood) when I did my retrofit.

[Silver_TT]

On ‎1‎/‎18‎/‎2018 at 9:23 PM, rockhouse66 said:

I think a car with a lot of miles on it and the original IMS bearing will likely do fine with pretty much any new bearing you use

 

You may do just fine with any new bearing you decide to use.  But there is substantial evidence to suggest that not all aftermarket bearings are equal.

[JFP in PA]

1 minute ago, Silver_TT said:

 

You may do just fine with any new bearing you decide to use.  But there is substantial evidence to suggest that not all aftermarket bearings are equal.

 

+1

[rockhouse66]

I wasn't suggesting a hardware store bearing.  The RND roller bearing is sold by LN, alongside the ball bearing and sleeve bearing options.

[Silver_TT]

No problem, I certainly didn't think you were.  Your comment just didn't follow, especially if you read further up the thread where it explained many of the considerations/differences in detail.  I was just trying to point out in a friendly way that thinking a car with a lot of miles and original IMS "will likely do fine with pretty much any new bearing you use" is a bit naïve.