Help Identifying IMS Bearing

Today I removed the transmission in order to replace the clutch, while in there I figure I get to the IMS Bearing but I do not know what type I have. The car is an 02 4S, but the engine was replaced in 07 by Porsche under warranty. Here is a picture, can one of you expert identify what type of bearing this car has. Thank you.

That is the large single row bearing.

That is the new style bearing that is not replaceable that does that doesn't have the failure rate as the other single row. I had asked the same question when I posted the same shot when I found the same bearing on my new motor. More info here, but everyone says to leave it alone, other than removing the outer seal. https://rennlist.com/forums/996-foru...-this-ims.html

I am doing this right now. Follow the bearing replacement procedure without removing the bearing. Just take the bearings grease seal off and Butten it up with new fasteners and seals. You should do the RMS while you in there...

OK, so I just remove the bearing seal from the side facing out. How about the other side, the side facing the inside of the engine? Yes, planning to do the RMS as well, and it looks like the oil pressure sensor is leaking a bit of oil in addition to been erratic, so replacing it also. The transmission mount is in one piece, but it has sagged quite a bit, so will replace it, what is the opinion on the function first insert?. I already have the deep sump from LNE, so that is going in as well. This car will be street drive, in addition to DE days.

Just the visible seal facing you. The bearing will be submerged in oil (about a third) when you fill it back up. Lots of threads you can read up on regarding FF inserts...Use the search function (upper right) for more info.

Hello Coopduc, So if Shft22's is an 02 4S and has the Large Single Row bearing. Would it be safe to say my 04 C4S has this same Large Single Row bearing? I have 138K on my vehicle and the RMS is leaking, might change out my IMS bearing too, but if just removing the seal would work, I am going to try that route.

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If your car has the original motor, then you have the original single row bearing that is replaceable, not the larger non-serviceable single row (those were in the mid-2005 to 2008 vehicles).

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You can't change that large (05-08) bearing without splitting the case. Your car may be an 04 model year, but the motor could have been assembled in 03. If your motor was replaced at a later date, who knows? The only way to know, is to see it. If yours is the large non serviceable bearing then yes, just remove the seal when you do the RMS. If you have not yet seen the PCA videos with JR walking through all the bearing scenarios, watch it!

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Normally an 04 would have the small single row bearing. The reason Shft22 has the large single row is because he has a replacement engine, they all came with the large single row.

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This is the mystery of the lifetime for me. I've been reading quite a bit on these two generations of 911 cars. Both having a potentially failure prone ball bearing design. Can anyone explain to me why on earth they didn't use the more proven plain bearing that is found on the Mezger based intermediate shafts?

There is a way to remove the bearing without splitting of the case. It uses a drill to widen the hole in the block so the bearing can be extracties. However I am not sure you want to do that. No comments further on the replacement bearing they use. You Tube I would not risk it but it is possible to extract it. Why no plain bearing? The IMS got much longer compared to the Mezger engine due to a redesigned driving of the camshafts. The reason Porsche used a sealed ball bearing instead of a plain bearing was that, due to the fact they dumped the dry-sump in order to cut costs, no proper lubrificarian could be foreseen on that side of the engine in a reliable and cost effective way. Take into account that the other side of the IMS has a plain bearing but it sits next to the oil pump so to foresee proper lubrificarion there was rather easy. Porsche made these �bad� engineering decisions in their struggle to survive as a car manufacturer. I have no doubt that the engineers involved were under serious time & budget pressure and for sure they have warned the accountants about the weaknesses of the engine design choices they were forced to based on cost cutting measures.

I am not sure that I would let the Porsche engineers off the hook so easy. They have been responsible for many bum decisions from the air cool days with magnesium case, steel / dilavar studs, 964 ozone prone distributor belts, 993 smog problems, so ... each model has its curse. The IMS is the 996 curse. Live with it, solve it, move on.

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I'm sure it had something to do with counting beans...

Yes I agree, solve the curse and move on IMS curse Bore scoring curse Running too hot curse Oil starvation curse and they get away with it...Well done Porsche! it lets me feel like a fool now!

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I'm not a mechanical engineer, but drilling into the block seems like this would add metal shavings inside the case causing the same failure problem they're trying to eliminate?

Thank you for all great info. When the weather cools down by the end of the month. I will be replacing the clutch, RMS and possibly looking into the roller bearing type IMS.

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It's insane! Watch him wipe away the shavings and then use the same rag to wipe the new bore hole.

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^^^^ THIS ^^^

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The engine in the video blew up. As one would expect, the block ended up with debris in the sump and that foreign object debris contaminated the whole engine and caused the engine to fail. We ended up puting Nickies in the customer's block and had to come up with a fix to repair the block to allow use of a standard IMS flange. Anyone who thinks that boring the hole in the case is a good idea should go right ahead and run, not walk, to have their block bored. That's economic stimulus for us.

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I have never done this procedure ( and I am not recommending it ) but my investigating of this procedure is that an air flow is directed into the engine from the oil fill to produce an airflow exiting the IMS bore to force the shavings out of the engine as it is bored. How effective it is at ensuring ALL debris is forced out is not proven and up for debate.If i had an engine with the large bearing, i would just remove the outer seal and run it, if the bearing started to fail and caught very early, since there would already be some debris in the engine , I "might" decide to do this procedure and take a chance of flushing the debris and capturing it in the filtering system, since the other alternative is a complete disassembly anyway..

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And I'd bet the forced air from the other end was an idea after the fact!

The problem is that if you flush still some debris could stay and slowly start damaging the most dangerous parts such as your crankshaft bearings. You risk compromising your whole engine when doing so. Even to the extent that a rebuild is not possible anymore. I myself will not worry about the bigger bearing failing And maybe with regular service intervals and other precautions you catch a failure in time. Although at that stage a rebuild might be also the wisest thing to do. I would expect such a bigger bearing to last significantly longer then the previous versions so at least you will be able to reach a certain high mileage where it starts to be interesting to do a full checkup and rebuild by splitting the case and give the engine a refreshed start!

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Wow, that's quite a story Charles. Good the IMSS can be adapted to M97. BTW, I think Jake is dealing with one large stock IMBS failure now. https://www.renntech.org/forums/topi...comment-297419

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Ouch! So much for me sleeping better at night...I wonder how many miles he had and if removing the bearing seal would have actually prevented it from failing?

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Probably, from the looks of the grim on the engine it had quit a few miles on it..

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I agree, these engine are extremely hard to flush the debris out of, there are SO many places that debris can hide, get stuck, not be able to flow back to the sump to be removed. V8's and in-line engines are easy to flush and nearly all debris can easily be flushed.Old flat tappet racing cams were notorious for failing during break-in. Dual or triple valve springs would have to replaced with light single springs and run for 30min for break-in, then removed and the high pressure dual or triple springs installed, Even then many cams would fail and leave debris all in the engine. But could be successfully flushed and raced. I had built a World Record Holding engine back in the 70's that during development was having cam failures. Would break-in the cam on light pressure springs then install the triple springs, the cam would fail in minutes. 20lbs less spring pressure the cam followers would fly off, 20 lbs more the cam would fail.Tried different heat treatment/hardness of cam/followers in all combinations,no luck. Motorcraft who was a sponsor of mine had just designed a new 20w50 Racing synthetic oil they sent me, it solved the cam failures.I probably went through a dozen cams failing on that engine and never had the engine fail due to debris.running it at 12k RPM for a season. The bearings looked perfect when dissembled.

Question??? Do I need to lock the cams and remove the tensioners in order to remove the seal of the large bearing?

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Yes

OK, so I may be in trouble here. Stupid, should had realize this. I remove the IMS cover without locking the cam or putting the engine at TDC. At this point nothing has moved, but of course I cant put the cover back on because the IMS bearing is a bit off center, a bit towards the right (while looking at flywheel) Should I try to find TDC at this point and lock everything up, or just remove the tensioner from the right side and see if that brings the bearing to the center? I am afraid to rotate the engine and jump a tooth on a chain.

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Yea, your in trouble !!! Do not remove any tensioners at this point !!! Remove the spark plugs to make the engine easy to turn, then slowly turn engine to TDC and lock cams, Turn slowly and with not much effort, if you feel anything "hit" STOP !!!

STOP! Wait for someone with more experience with this issue chimes in. I know that someone not long ago did the same and was able to get back on track...

Ok I�m stopping. Can�t believe I did such a stupid mistake. Lack of understanding on how this bearing is supported got me in trouble

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You had to treat this like you were going to replace the bearing, following every step and the procedure outlined to the T. The Single Row Pro instructions are detailed and if you omit the bearing replacement part of it, you should be golden. http://imsretrofit.com/wp-content/up...nual-03-23.pdf At this point, you are going to need to backtrack and make sure you haven't messed up the cam timing. Don't force anything if the IMS is off center and you can't get the flange on. That is the one word of advice I can provide where you may end up needing professional help.

Thank you, crazy thing is since I didn't know what bearing I had originally I had printed the replacement instructions and read them multiple times, I was very clear in the procedure. For some stupid reason on my part, when it was confirm I had the large bearing and it was suggested to just remove the seal, it didn't occur to me I had to follow the same procedure. So nothing has rotated on the engine at this point, I will remove the plugs and slowly rotate the engine until TDC, it seems to be almost there, at this point I should be able to verify all the cam slots are lined up, if they are lock them and then move forward.

Keep us posted. I'm about to do this in the next day or two (as soon as my tensioner seals arrive) I wonder if I should do the 2 case bolts too, motor has 50K on it?

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I'm trying to get this straight with the M96/M97 type bearings. I just watched the PCA videos on the three types of bearings. For the M97 engine, there are two bearings - smaller single row and a larger single row both of which have to be extracted by opening up the motor? The larger single row bearing induced from the factory in the 2006 model year has proven to be more robust and durable under the average (normal driving) load or was the dual row bearing on the M96 bearing more durable? The smaller single row bearing that was used from mid-2000 until mid-2006 the most failure prone bearing? This is the worst of all the three designs? And so, if you own a 2002 until mid-year 2006 911, you're pretty much in the "screw me from the factory" category? Or, is it that ALL the factory bearing designs are going to fail and that's why it's smart to replace them as preventive maintenance?

There are many more cars on the road that never had a problem. If you have a replaceable bearing it's cheap insurance to just replace it vs taking a chance.

So I was able to rotate the engine, very carefully after removing the plugs and I�m at TDC but I think I�m 360* off, this is a picture of the cam by the water pump. Can one of you experts tell if I�m on or 360 off.

I don't think you'll get the cam lock tool in it. Have you tried? Did you read the link that Charles posted? It states to rotate engine clockwise on full rotation (step #6) if not lined up the first time.

Haven't tried it, I don't have the tool yet. Hopefully will have one tomorrow, I have a friend that may have one. Again my original plan was to buy the solution from LN and "rent" their tool for a month, that all went out the window, so now I am behind the 8ball looking for tools. I don't seem to find this tool for sale anywhere, hopefully my friend will come through.

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Amazon Amazon

Yes, was just going to ask about that one. The description states is for a 997, I take it 996,997 3 chains is the same.

Yes it works...

Excellent its on its way. Question, if the chain would had jumped a tooth, is that something that is apparent by the position of the cam slots while the engine is at TDC. As they are now all the cams slots are like in the picture vertical and the engine is at TDC.

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Does this tool bolt down to hold the cams down when removing the cam cover? It looks like it has a hole to secure it.

Yes, you bolt it in place so it doesn't fall off.

From the pic in #39, it APPEARS that your cams on that bank are still oriented correctly. It also APPEARS from the tool marks on the casting that someone has been in there before with the cam lock tool. Now check the other head. Now, here's one mans opinion, with no guarantee, and no evidence to back anything up. I would gently put the cam tensioner back in on that bank right now to PREVENT a cam chain from skipping on the gear. When/if you rotate the engine, if there is any, any, any minor resistance stop of course.

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Thanks

The other head is exactly like the picture on #39, they are oriented up/down. I have not removed the tensioners, the only thing out of the engine is the IMS bearing support, which I have tied wrapped the bearing bolt to the engine case to prevent any further movement.

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Sorry, my bad. I misunderstood. If the other head looks the same, I think you've dodged the nuclear warhead. Get them locked down, THEN you can move the tensioner, align the IMS, carefully pick out the seal, and put the cover back on. Good luck, and my apology.

No apologies needed, yeah I am crossing my fingers that when the lock tools arrive I can lock these cam and move forward, will keep you all posted. BTW, I did remove the seal of the IMS bearing with a small pick, when I pulled it out it sounded like I had opened a soda can, something in there was pressurized, or holding a vacuum, at this time I had drained all the oil of the engine and had removed the RMS as well, so the engine was open to atmosphere. I found this interesting. Also there was no grease whatsoever in the bearing.

Oil migrates and packs in behind the bearing into the IMS hollow shaft. It's one of the possible failure modes, that when the oil is changed, that oil trapped behind the bearing is not exchanged. Hence - removal of the seal allows SOME of the trapped oil to come out. If only we could remove the inner seal. hmmmm.

Yeah I understand the oil in the shaft issue, thing I found interesting is that it was either pressurized or on a vacuum state, and this was apparent when removing the outside seal, so I wonder what state the inner seal is at, it must be somewhat open to the shaft. Also no oil came out off the bearing when the seal was removed, there was oil residue when the IMS support was removed, but after removing the bearing seal nothing came out. Just sharing my experience here.

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If your bearing is dry, I'd say it's a good thing you did this now! I need confirmation on the tensioner removal. From what I've read, I don't need to remove the third one (front) just the two on the backside correct?

According to the instructions for the bearing replacement you have to remove all 3. My plan is to start with just the two in the flywheel side and see if the bearing comes to center. Unfortunately I wont be able to touch the car until Friday, maybe even Saturday I will post back how it goes then.

OK, so last night I was able to lock the cams after rotating the crank one and one quarter revolution, the first TDC I could not get the cams to line up just perfect, so I rotated it another revolution and then the cam lock tool got in no problem. Before I did this I had secured the IMS bearing bolt with tie wraps in order to prevent any further movement. As soon as the rear (flywheel side) of the engine cam tensioners were removed the bearing returned to center and I was able to install the support with no issue and very little effort, I did not have to remove the third tensioner. I slept good last night.

Woohoo! Nothing like a good night sleep when you've been stressing about something. Glad to hear you've got it back together, or at least the worrisome part.

Nice!

She is back on the ground and running perfectly. So in addition to the new clutch/pressure plate, I also replaced the RMS, took the seal off the IMS bearing, replaced the spark plugs and the oil sending unit, which was completely loose and leaking oil. Thank you all for your advice and guidance, till the next project then, 160f thermostat.