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Why Replace a Good Dual Row IMSB? Advice

leoj65
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leoj65 Member

leoj65

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Hello, I have not seen this exact IMSB question before.

I am aware of all the different IMSBings out there and the discussions about what's better, not asking that question. I have my 1999, 996 engine apart because it was making non magnetic metal at a decent rate. I believe that problem is solved and I am reassembling it at the moment.

My question is this:
My dual row IMSB seems to be in perfect condition. Seal looks good and it turns smoothly, no play. I am thinking of just putting the IMS back in the car as is. Then replacing the bearing at 60k (32k now) when I do my clutch. I can't think of any reason to put in a non sealed bearing now with engines history of making metal even if it may be solved. I plan on having two magnetic drain plugs and just swapping them out every 2k miles or so to check for any ferrous metal particles just in case. Replace bearing? Remove the seal? Leave as is?

Any thoughts?

Joel

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JFP in PA Member

JFP in PA

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Welcome to RennTech :welcomeani:

If you have already extracted the IMS bearing from the shaft, you cannot reuse it.  The process of extraction damages most of the internal components of the bearings, which will lead to quick failure.

 

If you have not extracted the bearing from the shaft, even though the unit feels relatively smooth means absolutely nothing. I would be willing to bet that there is already no grease inside the bearing, and the seals are hard as well.  It would be false economy to not replace it.

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BufordTJustice Member

BufordTJustice

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I agree with Jeff.

 

Also, if metal byproducts are that much of an issue, you really need to step up to an LN screw-on filter adapter (with a quality screw on filter like a Napa Platinum, Fram Ultra, Royal Purple, etc) and a full-circle FilterMag setup (two filter mags) along with very short oil change intervals.

 

However, I'm still kinda alarmed. What did you find was causing the metal to be present in the oil?

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judgejon Member

judgejon

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Hi, Leo.

Welcome to the forum.  I was in San Diego in late 60's and early 70's.  I remember it all too well.

So, your question is really a classic "no brainer."  Jeff is absolutely right.  Please do not reuse your old bearing.  Mine is actually sitting proudly on a bench out in the garage, along with an internal oil pump, and 2 timing chain tensioners from my 911sc.  These are all very pretty and interesting to look at.

Seriously, strongly consider going with an LNE retrofit bearing or putting in the LNE Solution.  I will be facing this question in about 10k miles.  Not to replace, but to replace with which of the two.  I'll probably go with the Solution.

This is all somewhat problematic, because there is simply no known way to predict when or if an IMS will fail.  This issue resulted in a successful class-action lawsuit against Porsche, and lots of money got paid to people who purchased a 996 only to have the engine blow-up.  Literally.  Others, like myself, never had a problem, but for peace of mind changed over to the LNE retrofit "just because."  I still feel it was money well spent, and still enjoy winding it up every now and then.

For your own peace of mind, and because you have the ability to do the work yourself, and because you already have the engine apart, you should put in the update.

Lots of info on the forum about this issue.

Good luck.  Cheers,

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judgejon Member

judgejon

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25 minutes ago, BufordTJustice said:

I agree with Jeff.

 

Also, if metal byproducts are that much of an issue, you really need to step up to an LN screw-on filter adapter (with a quality screw on filter like a Napa Platinum, Fram Ultra, Royal Purple, etc) and a full-circle FilterMag setup (two filter mags) along with very short oil change intervals.

 

However, I'm still kinda alarmed. What did you find was causing the metal to be present in the oil?

 

There you go.....

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leoj65 Member

leoj65

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Posted (edited)

Thanks for the advice all, pretty much cemented my thoughts.  Bearing is still installed but will be coming out now.  Screw on filter adapter was already for sure, and now LN ceramic dual row is too.

 

Joel

Edited by leoj65
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JFP in PA Member

JFP in PA

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26 minutes ago, leoj65 said:

Thanks for the advice all, pretty much cemented my thoughts.  Bearing is still installed but will be coming out now.  Screw on filter adapter was already for sure, and now LN ceramic dual row is too.

 

Joel

 

Good move.  Also replace your RMS and AOS while the car is apart.

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leoj65 Member

leoj65

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Have all new seals and Porsche AOS ready to go.  Was going to replace the cam chains too?  Water pump feels great and the fins are solid.  Would you replace all the guides regardless of condition?

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JFP in PA Member

JFP in PA

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1 minute ago, leoj65 said:

Have all new seals and Porsche AOS ready to go.  Was going to replace the cam chains too?  Water pump feels great and the fins are solid.  Would you replace all the guides regardless of condition?

 

Yes, I would replace it; the water pump is a maintence item, so it should always be replaced.  I would replace the chains and get the LN chain tension paddles as well, and I would very carefully go over the oil pump, replacing it if it shows wear.  If it is good, I would get the $20 oil pump pressure relief spring and piston update from Porsche, and I would replace the investment cast oil pump drive shaft with the chrome moly unit from LN as well.  Basically, anything that could suddenly crap out and ruin an otherwise good day should be done while you have access.  :drive1:

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leoj65 Member

leoj65

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Maybe the metal flake in the link.  It was just floating around in my sump. Looks to be casting piece that broke off as one side has the same machine marks as all the other surfaces in the case.  There really was a poor job done cleaning up the castings edges.  There were no other indications of chains or anything else impacting the cases.

 

OR

 

My thrust bearing was shedding quite a bit of metal so that may have been causing the aluminum as it went through my oil pump and other areas. The scavenge pumps have scrapes also so any little particle stuck in there just makes aluminum as they go around and around.  All these things have been fixed and the metal has hopefully 99% cleaned out so we shall see........

 

https://drive.google.com/file/d/0B1MreK5EPyf9OXlWUkpSN0ZPZjA/view

 

 

thrust_bearings_5719dfe5896487d1cd1a40f65ea4bb1c12f08ba3.jpg

 

oil_pump_2c54e512e1a1e9362da5fed3385dd42c533f0eae.jpg

OIl Pump housing.

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