Metal Shavings Behind LN IMS Bearing - Need Advice!
 

I'm totally devastated right now. I was in the process of pulling IMS bearing out of my engine to replace as well as install the DOF kit. The existing bearing is an LN dual row ceramic that was installed by the PO (at an indy shop) 8000 miles ago, and here is what I find:

http://986forum.com/forums/uploads01...1397083563.jpg

There was about a cup of oil that came out from the IMS tube. I drained the oil several days ago, so it didn't come from the sump. I inspected the filter tonight and see a few metal specks in it, but nothing like what is in the IMS tube. I taped paper towels to the handle of my breaker bar and cleaned the inside of the tube several times like the barrel of a gun. Lots of small sparkles came out on each paper towel.

I'd like to believe the metal came from the IMS bearing because of the buildup on the seal. Anyone have any opinions? I have been looking at engine parts drawings to try and see if there is a ball type bearing at the other end of the shaft, and if so, how do I test it to see if the metal flakes were coming from that end? When the bearing was still installed, I could feel ever so slightly some play. Once it was removed I felt it again, then rotated it and couldn't feel it. Not a big surprise, but turning the bearing gives a slight "crunchy" sound.

What do I do next?

The other end of the IMS is a one piece integral bushing, that fits inside a larger bushing formed by the front coolant manifold behind the oilpump. This design is basicly trouble-free & not the source of the shavings. I'm guessing those shavings came from the oem IMSB & were not properly removed during the LN retrofit. If I were you I would send a e-mail to LN & try to consult with them. LN may want to know who installed the retrofit.

Are the metal bits ferrous (can they be picked up by a magnet)? Do you have a photo of the other side of the bearing?

I would tend to agree as if the bearing itself were tearing itself up, the metal would be in your oil..........

looks ferrous; actually looks magnetised in the image.

If there is a bushing at the other end, then I am all but convinced the shavings came from one of the IMS bearings. One would think that the installer of the LN bearing would have noticed such a thing and cleaned things out or something along those lines.

No matter which one it was, it's not going back in the car as I have a new bearing. My real worry at this point is how to effectively clean as much of the flakes as I can, hopefully without doing a complete tear down.

Yes, they shavings/flakes are ferrous.

Also, 8000 miles ago any oil in the tube would have all but drained out when the LN was put in, so all of the oil that drained out this time is "new". Can oil get in from the bushing side, or is it only possible to get in from the flywheel end? (ie, through the bearing and past the seal?)

Hmmm, a Black 2000S? I seem to remember a Black 2000S last year with a DIY IMS retrofit that just turned into a massive train wreck with the owner in well over his head. I wonder if this is the same car.

Yes, the bearing is actually slightly magnetic. I think the back of the bearing was acting like a magnetic drain plug.

Well, as I understand it, Porsche made more than one black 2000S. I have owned it for a year and the PO I have become friends with since the purchase and she had it for a year and I know she didn't do any work on it herself, it was all Stealer work that she had done. The previous PO had the bearing work done.

OK, I've been sitting here trying to make myself feel better and have thought of two points (rather, clarifications of points that you guys have made).

IF it were the current bearing making the flakes, most, if not all of them would be in the oil and oil filter since that is the path of least resistance, and not push their way through the seal to end up in the tube.

IF the original bearing began to fail, and the inner seal (since the originals had two seals) failed, it would introduce flakes into the tube (and perhaps not into the oil/filter, but we will never know). Those flakes might not be that noticeable if the original bearings weren't magnetic and if the outer seal didn't fail, thus no or very little oil in the tube. The flakes would just migrate around in the tube and not be attracted to anything in particular. Introduce the magnet and the single seal bearing, and you have an opportunity for the flakes to float around and make their way to the weak magnet of the bearing.

Sound plausible?

The IMS drive is loose and creating wear debris as it chatters on the IMS assembly. This is allowing the debris to get inside the IMS tube.

Not new, this is mode of failure #25, first noted in 2012 and seen 3X since then here.

I could be wrong, but the symptoms are exacting what we've seen before.

Thanks for the input, Jake. How do I confirm this? I don't understand what you mean by IMS drive. Is this the sprocket that is connected via chain to the crankshaft?

That IMS bearing appears to have plastic seals on it. Don't genuine LN bearings have NO SEALS on the sides?

The bearing race is marked "SPC". I did some Googling and SPC generally notates a ROLLER bearing. I'd guess a roller bearing with considerable side load would generate metal chips.

To quote General Buck Turgidson, I hate to judge before all the facts are in, but I think your PO may have been had by an unscrupulous shop.

It's not a roller bearing, I can see the balls in it. It also doesn't say SPF. It looks like JAF, Japan, and 5204 Here it is with the debris wiped away:

http://986forum.com/forums/uploads01...1397089785.jpg

When did LNE outsource to Japan?

If I'm reading the numbers correctly, it would be this:

Amazon.com: 5204 Nachi (JAF) Angular Contact Bearing 20x47x20.6 Japan Bearings: Industrial & Scientific

Definitely NOT an LN bearing.

Link to get JAF full line catalog here.

JAF Bearings Catalog | AST Bearings

The IMS shaft is 4 pieces that are lightly press fit together. The drive can separate from the driven components and when this occurs the precursor is wear debris like this. There's no way for this to get out of the shaft, until the shaft separates, or the bearing is pulled.

Or a hack installed the bearing and left debris from a previously failing bearing in the tube/ engine.

I know JPF doesn't like the Dempsey "set screw" method of locking down the IMS sprocket. IIUC he thinks the sprocket can be pushed loose from the shaft, as it's a press fit.

Beaten to it by above posts by Jake & Dennis...


Benjamin.... What bloody awful luck, its everyones nightmare what you have just discovered.
That certainly looks like a standard quality, off the shelf 5204 bearing - not a ceramic hybrid bearing. It will be interesting in what Jake Raby has to say regarding the cause of assembly chatter

I think the minimum you are going to have to do is:
A) remove the bearing seals (are there 2 seals?) and determine how much wear there is on the bearing races and balls.

B) Get a strong magnet deep into the IMS tube to get any more debris out - papar towels won't remove all.

C) Do you have a magnetic sump plug? Even if you do, it would be wise to remove your sump plate and determine if there is any more debris laying in the bottom of the sump.

You MAY be lucky that the bearing seals have kept the metal shavings on the inside of the IMS tube, but I think you may have debris already in the system.
Best of luck - keep us all posted on the outcome of your problem.....

Post pics of the opposite side of the bearing.

Short of tearing the engine down, is there a way to confirm this is the problem?

I don't understand why anyone would trust a $20 bearing for this application!!!
If its a cheap iron bearing, these can definitely show signs of magnetic wear like this... but what kind of shop would do that??? Some shops really need to keep their fingers out of engines - Scary!

5204 JAF NEW Double ROW Ball Bearing | eBay

No.. Even torn down you must measure for drive runout to find this issue.

http://986forum.com/forums/uploads01...1397094258.jpg
http://986forum.com/forums/uploads01...1397094284.jpg
http://986forum.com/forums/uploads01...1397094303.jpg

So, what do you suggest?

It looks like others are right - your bearing doesn't seem to have the markings of a genuine LN one. Not that knowing this helps you. See the two pictures at the top of the following page: Is it Genuine?

You got one of these? Mine is in the drivers side door jam.
http://986forum.com/forums/uploads01...1397109363.jpg

One reason to stick with OEM bearing! Am I the only OEM imsb advocate on this forum?

That does not look like an LN bearing................

http://imsretrofit.com/wp-content/up...ofit-p-93.jpeg

Post a pic of the housing bore of the IMS that this bearing was fitted to, please.

Yes, you answered your own question.

I hope these help. If not, let me know and I'll take more.

http://986forum.com/forums/uploads01...1397146731.jpg
http://986forum.com/forums/uploads01...1397146744.jpg
http://986forum.com/forums/uploads01...1397146761.jpg
http://986forum.com/forums/uploads01...1397146774.jpg

Because the IMS is a sealed assembly here should not be any communication between the engine oil and the inside of the IMS. That means the inside of the shaft should be dry, the fact that they are frequently full of oil is just a symptom that there is another problem. Oil can be forced through the bearing seals washing out the grease of the OEM bearing which greatly limits life. I suppose if the press fits are failing oil could enter there as well. The fact that the chips are on the inside of the shaft behind the bearing seal makes one think they may have been generated inside the pressed on shaft. There have been threads with borescope type cameras on this thread recently. You need one of those. Clean out the inside of the IMS tube and look at the interface between the pressed pieces and the tube assembly. A magnet is not effective in pulling chips off a ferrous surface. I'd go in with solvent and a cloth (not paper towel) followed up with a dry microfiber cloth to trap the fines. As the particles are in the tube, it is likely you will see damage where the parts meet inside the tube if you use a borescope camera. That beats splitting your engine case by a mile. Sorry to see you're having this trouble.

This is what led me to believe I had an LN bearing installed. From June of 2010:

http://986forum.com/forums/uploads01...1397147247.jpg

If you look that part number up, it's the LN bearing kit.

It seems like everybody on this board, except for Jake Rabey, believes that all LN bearings are non-sealed and their branding stamped on the outer race. Hopefully Jake Rabey will chime regard to which bearing brand was used (OEM, LN, or others).

IIUC the OEM IMS bearing for Porsche is from NSK (Nippon Seikō Kabushiki-kaisha).

Hmm...customer supplied clutch and RMS, 6.5 pints of generic 75W-90 gear oil for $24.38 which from price alone isn't the Porsche fancy gear lube. No line for motor oil - did the shop just reuse the old oil drained out?

LN bearings are not sealed on the center bolt side, and have specific markings that identify them as the real thing.

Hmmm... have you called shop to inquire if they put a LN in the car? I would.

If shop claims it to be LN and it ends up not (as signs indicate now)... I sure hope you show the entire receipt naming the shop to protect others...

Good luck :)