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That's a questionable catch-all conclusion, really only works if your bypass failed which is only the case in a small percentage of cars. The cartridge filter is inherently full-flow in design too. Simply has a potential for the bypass valve to fail, but as long as it's doing its job properly you really cannot conclude that broken IMS always equals grit in pressurized oil passages. Unless IMS damage also always destroys your bypass valve🙄. The spin-on just ensures the bypass failure mode is removed. But really, if you have a faulty bypass valve and you're constantly running unfiltered oil - with or without grit -, the engine shouldn't even make it past 10k km from the increased overall wear, everything will grenade. I have mailed with the LN guy, and they tried to charge me 350 bucks an hour to even mail with the guy, rofl. He answered 0 of my questions, probably because I said I'm not in the US so i'm not a potential customer. I'm not even joking, I wish I were.
In all my posts I'm assuming the use of a full-flow non-bypass filter. I've disassembled the oil case, the oil in the sump doesn't reach the crank by a long shot. There's only a small window to the crank anyway. The splash coming from the sump will be minimal at best. But even then, oil circulates at a pretty serious volume. The volume in the sump will not be there for very long before all that oil has been worked through the filter. In the end, the vast vast majority of all grit will reach the filter. Your story only holds up if the oil in the sump is permanently contaminated and does not get rid of its grit. It will, cause it will be sucked up by the oil pump and pushed through the filter. My issue is this: When an LN Full-flow adaptor needs to be sold, the sales pitch is "this will filter all of the debris protecting your engine, you absolutely need this if you want to be certain your journal bearings receive clean oil at all times!" Then, whenever any amount of grit is in the engine, the sales pitch targets a full rebuild and the tune changes to "yeah this will get anywhere nothing will help, your engine needs to be taken apart completely". It's either-or, not and-and. You can't have the LN adaptor both filter grit and not filter grit depending on the sales pitch that needs to be thrown. Either it works, or it doesn't. There are two options, really. 1) The filter works, protects your engine from grit, saves your bearings. 2) Any amount of grit (so even a few pieces) destroys the bearings, the existence of spin-on adaptor + fullflow filter is moot. So which is it? It obviously can't be both.
Well.. How? I've read that sentence so many times but the 'how' is always missing.
That's very helpful, thanks a bunch 🙂
I know, and I thank you for the willingness to discuss. I wouldn't say I overlooked it as I specifically did mention "without a faulty bypass valve". Assuming a clean, full-flow oil filter, which components are at risk for getting damaged by grit as it's on the way back to the sump? I'm still figuring out the exact oil routes in this block, but I suppose it cannot reach the main- and rod-bearings, right?
I won't be liked for saying it, but to me it just doesn't add up, thinking about it critically from an engineering standpoint. On the one hand, "any and all ferritic debris is bad and requires an engine rebuild because the 'grit' keeps circulating." At the same time, apparently "small ferritic debris that pass through the oil filter are not as much of a problem", as it doesn't disqualify an engine for a retrofit. Sure, the magnet is nice, but apparently it's not that big an issue if you don't have one. Then, if you had an IMS go, apparently the big grit is a 'huge problem', even though the oil filter fully catches these particles before the oil is sent to actual critical pressurized components. Grit won't 'circulate' through the engine as it will only meet the oil filter once. You'll catch it and even if some gets dislodged elsewhere and ends up in the sump, it'll be picked up by the filter before it's circulated. I'm confused about the reasoning, it seems contradictory. So after an IMS failure, cleaning as best as possible with the engine in the car, you'll have some remaining debris of which: - The large particles and grit will be caught by the oil filter before going to critical engine parts. None of these will pass through. - The fine particles that pass through the oil filter were not really that much of a problem anyway apparently, as it doesn't disqualify for a retrofit and is deemed 'normal wear'. I don't see a solid, scientific reason why the engine cannot be fixed instead of rebuilt. Be it with a service interval on the IMSB. I've seen anecdotal evidence of 'people who blew their engine 75 miles after', but what's to say they never cleaned their oil system, didn't bother to replace their filter, or had a faulty bypass valve - this doesn't mean anything at all. I have yet to read a solid reason on how the debris can cause mayhem elsewhere. Even if an IMSB went, with a fully properly working oil filter without bypass, there is no way for these debris to end up in any of the critical pressurized systems as far as I know. Is this wrong? If i'm not, it comes down to how long a new IMSB can survive in the splash-oil that may have a small amount of leftover debris in the sump. Obviously, use one with seals in that case, not an open bearing. Obviously, flush the engine thoroughly with fresh oil after cleaning as best as possible with the oil pan off. Hell, if you'd fit the pressurized IMS solution, you shouldn't have to worry about the sump oil anyway, since it gets fresh fully filtered oil. If I'm wrong, what brainfart am I making here? I fully understand that taking it apart and cleaning everything is the absolute best option. From an engineering standpoint, I simply don't see how it could ever be the ONLY option.
Few additional questions though, cause I've read some of your contributions in other topics, like with stick-on magnets and so on, which indicate that there is always some tiny ferritic particles sloshing around, which can also pass through the oil filter. These are not a problem, then? What size is 'too big' and would they not be caught by the oil filter?
Well, sure sounds to me like I've got a totaled engine sitting in my car then. I have the time and knowledge, but don't have the resources to rebuild or buy a working 996 engine. Engines I've worked on in the past survived a lot worse and were 9/10 times fixable. Seems like I bought myself a glass box, such a shame it didn't present symptoms when I bought it 3 weeks ago. I know when to take the loss and walk away, I'll probably sell 'as-is with broken engine' and have learned an expensive lesson 🙂.
I know of LN Engineering and boy, have I read extensively these past 3 weeks. I suppose you work there and/or with them? They're not an option for me since I don't live in the US. I'm not talking about the LN Engineering Retrofit - I know my engine would never for the life of it qualify for one since it's an open bearing. I have read the selection criteria. I would install a closed bearing, for which there are several options still. So, again, just to be clear; IMS failure of any kind = engine totaled, by your standards? Since, put in the most simplest of terms, you can't use it without taking it completely apart, so the motor is beyond repair? I chose those words carefully. You know as well as I do, an engine rebuild costs upwards of 7000 bucks. Even if components can be re-used. I don't consider that a 'repair', but rather 'building a new engine while re-using the main parts of an old one'.
So, after IMS failure with grit, an engine is pretty much written off then? A full rebuild costs a ton of money, which I don't have to spend unfortunately. I could live with periodic changes of the IMS bearing, as an interval maintenance part and something I could do myself. Using the standard bearing (not too expensive then), this should be a viable option for those who don't have the cash to take the entire thing apart? I agree cleaning it is the absolute best course of engine. But I refuse to believe an engine cannot be kept in reasonably well state with periodic parts replacement and premium maintenance. If I understand what you say correctly, any engine that had IMS failure - even if caught before total failure - will never work 'properly' if it's not fully taken apart which is basically a rebuild, and no IMS solutions are available that will not fail?
If the bearing works as intended, I kinda don't see why. That is, if the original philosophy of a sealed bearing was adhered to. It was not fitted with a ceramic retrofit - with those I can understand the argument, since it's engine-oil lubricated. With a sealed bearing, oil should not be coming in in the first place, let alone the contaminants. Add the full-flow oil filter and the tiny grits should be mostly gone after an oil flush or two. Aside of that, how much work/cost in terms of parts is it to pull the engine apart? How far apart does it need to come? The pressure-fed journal bearings receive clean oil at all times, so I guess those can be skipped?
Yeah I already did before, like a week ago. There were ferritic metallic shavings in there before the grinding noise started presenting itself (about 300 km ago). The mechanic that installed the replacement bearing 13000 km ago convinced me it was leftover debris from the previous bearing, which was in pretty bad shape. Guess not. I'll check my filter tonight probably once more, but I expect there to be metal shavings yet again. Then it's on to find out why this bearing failed so quick, since it was a dual row FVD Brombacher replacement...
Well I ran it without the belt today, and still had the noise. It's almost 1:1 what OP showed, so I think OP never replied back because he grenaded his car: I listened and recorded the sound, measured the periodicity of the grind and determined it to have a 'frequency' of 316 RPM. Now, nothing in the car syncs up with 316 RPM. Idling, my engine runs 780 rpm. Camshafts go 1/2 that, so 390 RPM. The IMS shaft goes 0.67x crank, so 523 RPM. Couldn't think of anything else spinning at this weird fraction, until it hit me; the balls in a bearing go 1/2 the speed of the races, while the balls also have a shorter distance to travel because they're on a lower radius (more towards the center, smaller circle than the outer race), so complete 1 revolution 'faster'. Correcting for the lower circumference the balls have to travel compared to the outer race, which is a factor 1.24, I came out on the balls inside the IMS bearing rotating with a frequency of 523 (shaft RPM) divided by 2 (balls go twice as slow) times 1.24 (distance in travel between outer race and balls itself) = 324 RPM. Which is very close to the 316 I measured from the sound. So I'm pretty sure my IMS bearing is very close to grenading. And I think OP's was too.
So sorry to bump this post, but did the water pump fix it? I figured the water pump spun faster than the crank pulley, so the periodicity of the grinding noise should be a lot faster at idle? If anyone else can chime in, I have the exact same noise right now in my 996. It's driving me crazy, and I dare not drive the car almost.