IMS Replacement Mileage vs Time ?

I know the whole IMS thing has been talked about at great but here goes: Recently added a 996 Carerra with M96 engine to the fleet. Its a model year 1999 (build date 98), so it has the dual row IMS and has been updated with the LN Engineering dual row bearing in 2016. Since the IMS update was down 6 years ago it is due to be replaced based on the 6 year or 75000 mile change interval, as specified by LN. However, the car has only done around 11,000 miles since the bearing swap. I plan to drop the oil pan and have a look around, as well as cut apart the filter to look for metal, and assuming none is found am wondering if its worth doing the bearing again, or maybe I can let it go for a while since the mileage has been so low..I guess Im leaning towards replacement, but wondering what others would do.

I suggest you simply reach out to LN and discuss it with them. They are active on this forum and @Charles Navarro or someone at LN I'm sure will give you good advice. I can't image you should spend the $ with only 11k on the replacement but see what the experts say. Good luck and welcome.

Well, given all the posts on this subject and other topics, what kind of gambler are you?

How many times has the oil been changed in the last six years and 11K miles? The problem is that the replacement IMSB has timed out even if the previous owner had changed the oil 12 times in the last 6 years. I�d replace it with the Solution if you plan on keeping the car. (That�s exactly what I did)

If you know anything about how an anti-friction ball bearing wears, it is proportional to total revolutions, not time. You do need a clean lubricant, which I'm sure you have. I have no idea why they would suggest a time interval that is so short.Someday it could degrade on time, but not in six years with operation on the engine during that time. I have my original IMS bearing on my 99 and I'm not changing it anytime soon.

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I called LN last week to discuss. Was really impressed that they (not sure who I talked to there) took the time to chat about my concerns. Truly good people there. Unfortunately, the conclusion was that it may be totally fine, or it may not. No real definitive answer either way. Lots of factors to consider like oil change interval, driving style, track use, etc..

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This was kind of my thought but Im still on the fence if the added piece of mind of replacement is worth it. Id do it myself in house, so there would be a pretty good savings on labor, and would use the IMS solution so as to be one and done with it..

If it's something you can do yourself, I would think that it would give you peace of mind to do the Solution and never worry. Just my 2 Cents......

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This ^

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Something to think about. Imsb, clutch, flywheel, rms, oil cooler, UAOS, spark plugs, ignition coils, water pump, coolant reservoir, are all things you can do when you drop your engine to do your imsb. Sure, may make sense to change them at that time. Be a shame to do the imsb and not do the others, but the parts cost money. Sales are coming up in November at LN. If you want piece of mind, stock pile the parts on sale and do it all at once. One less thing to loose sleep over unless you can sleep thru anything. Yes, I have put my money were my mouth is and just did my second refresh in 10 years a few months ago. But i have owned mine for 20 years and am looking forward to the next 20. Your call. But I hope this helps to think it thru.

Spoiler I would drop the sump and look for brown plastic bits. Get or borrow a durametric and get the cam deviations. If they are out of spec then you should think about doing the variocam pads and small chains. Since you have the LN IMSB cover you can also consider the skf 6204 dual row bearing. It�s about $40.

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Bearing change intervals are a difficult topic. If Porsche had originally specified a service interval to change the bearing out, we'd probably not be having this discussion now. I had hoped when Porsche released their replacement which used a sealed single row ceramic hybrid ball bearing that they would specify such an interval, but that never happened unfortunately. Like a water pump or timing belt, the IMS bearing is in service 24/7. Besides having a load on the bearing even when it's not in operation, the bearing is exposed to oil in the crankcase and with that, combustion byproducts that combine with moisture to form acids which can cause corrosive wear. Short drives, long drain intervals, crappy oil, etc. all come into play. There are also outside factors that can affect the bearing like runout in the intermediate shaft (gear is pressed onto a tube and can just come off - we've seen it happen!), contaminants in the oil (silicon from scored bores for example), or brinelling of the bearing (which can be caused by a multitude of factors such as shock, excessive load, vibration, improper installation, etc.). Where we often see factory bearings with flat spotted *****, the ceramic ***** don't flat spot, however they are harder than the races and can dent the races, leading to an imperfection in the race or wear scar that will get worse over time. One such cause is worn out chain tensioners or some other debris ingested by the bearing. The cages are rated for 250F and intermittent jaunts to higher temperatures, but they too can be compromised and will age differently based on a multitude of factors. As with anything mechanical, it's impossible to make it 100% fail proof so it's hard to give an answer on when the bearing needs to be changed out. All we can do is come up with processes and recommendations to best mitigate potential issues and why we recommend proactive replacement based on time or mileage, whichever comes first, and we offer solutions that either have intervals like the IMS Retrofit or the IMS Solution, which is permanent and doesn't require any future servicing. The IMS Solution has the added benefit of likely being reusable after an engine failure such as bore scoring where any other bearing will be contaminated by said failure and require replacing.

I'm in the same boat, the single row LN retrofit I purchased the car with has a service life of 4 years or 50k. I'm at 8.5 years and 39k at this point. Blackstone analysis each oil change (3k miles) come back clean and my indy shop tells me to "just drive it" so I haven't gotten around to doing another retrofit yet. Interested in what you decide to do.

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I do want to point out that used oil analysis cannot be used to determine the condition of the ball bearing. Any debris generated by the bearing will be larger than the range of particle sizes it can detect unless you do additional testing for particle size and count.

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Would debris this size show up on a magnetic plug or in the filter?

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Some really great info and insight here. Thanks for taking the time to post such an informative response. I think after some consideration (read obsessing) I'll plan to drive and enjoy the car as is until winter arrives and the road salt starts flying. Im in the Philadelphia suburbs and the amount of road salt they use here is criminal. At that point the car will mostly hibernate for the winter, so I'll plan to drop the pan and have a look around, check the bores with boroscope. If all looks good plan is to install IMS solution and be done with it.

Extreme case: I change out my IMS bearing, then park the car for 7 years. I come back to it, do everything else to fire up the car. I don't think I am changing my IMS bearing again. If it were me, and it's not, I would drive the car, change the oil at 5K miles, inspect the oil filter every time for any sign of metallic residue, check the cam shaft deviation to see if it is within spec and has not gotten worse, and continue driving. Whenever I get to my clutch change interval, I sure as hell would change the IMS bearing. I guess I am in the mileage camp.

...and in some cases the weakest part of the car is the nut holding the steering wheel

I'm also in the mileage camp. I have a LN bearing replaced in 2017 and since the car has done maybe 25k km (15k miles). It was done with the clutch at the time. I can't see myself doing it again unless I need to drop the tranny. Maybe if I replace the transmission mount but I'm running a function first insert for now that's been great. I'll typically do 2 oil changes a year regardless of miles (parked in winter) and cut apart the filter each time.

I think the general consensus/guidance is this: If the car is driven regularly, then mileage is a safe bet (60-75k mi.?) If the car isn�t driven regularly (say only in good weather, no winter, less than or equal to 5-7k/yr) then the Time interval takes over. Or, do The IMS Solution and there are no further worries with the IMS bearing.

All good points. I truly believe that my bearing is totally fine, and would be good to go for many miles, but since there really is no definitive answer, and the IMS solution is a permanent fix, I think thats my plan. I can do it myself (I think) so its just parts costs, so not terribly expensive. Add it to the list of winter projects. RMS, AOS, etc were all recently done by PO so good to go there..

You might consider upgrading to UAOS while you're in there, especially if the car is a keeper. IMS Solution is the right way to go, even better that you can do your own work. Good Luck.

Wrong forum, but I've replaced the IMSB in my 2007 with an LN ceramic bearing that I will never change again, time or miles, unless the engine grenades.

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I will throw out there that we do have an ongoing promotion for those upgrading their Retrofit bearing: https://imsrebates.com/ We extended that to other brands of replacement bearing kits and in fact we're seeing people upgrading their EPS and FVD bearings taking advantage of our promo. We also offer free tool rental including the RMS tool: https://lnengineering.com/tools-rental Over the winter, might be a good idea to run down the list on preventative measures for bore scoring as well, which I've outlined here: https://lnengineering.com/products/w...e-scoring.html

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Considering that a 2007 should have the large upgraded (and not easily replaced) bearing with little to no failure rate, this is not a controversial decision 👌

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Quoted for truth. ;-)