996 Intermediate Shaft Failure Prevention / IMS Bearing issu

Hi Guys, I was talking to JZMachtech yesterday who advised me of one of the consistent issues with 996 (and 1st yr of 997) 911's - the Intermediate Shaft and Bearing failure. Apparently, in these models there is a propensity for the bearings to split in rotation during usage. Obviously, if this happens then the shaft and bearings could disperse across the engine bay. Result: total engine failure, with the only option being a complete engine rebuild. Autofarm have advised me that due to the excessive care taken by owners of my car in servicing the car this issue should not occur as engine oil will periodically have been changed. If the bearings were on the way out then this would (apparently) have been seen in the oil, and further investigations instigated. That all said, Autofarm have invented a special tool for removing the shaft, and have new (non failure) bearings to add to the assembly. Obviously, to be ultra careful, anyone with a 996 could consider doing this in advance of the 'potential' catastrophic failure. However, doing this means a bill of £1400 excl VAT as the engine must be removed and the whole area disassembled. Ouch! But not as OUCH as the bill for a complete engine rebuild! My question is this: are there any warning signs of impending IMS failure? Also how common exactly is this issue? Is it worth as a matter of course to replace the part, or is it worth taking the chance given the nature of the consistent Porsche service history? I should also mention that the GT and Turbo 996/7 models do not suffer these issues so those of you with these cars are exempted. Any thoughts would be much appreciated. H :judge:

I have a good friend who is in the market for a 911. He has £20k to spend and wants a pre facelift 996 with a GT3 kit. He has found 2 or 3 very nice ones, but is worried about the shaft failure.. I have advised him to go for a higher miles (60-65k) facelift to save the worry, I know they too can fail be the % in a lot lower. His problem is he loves the GT3 MK1 look ! this could be the answers to his problems :thumb: If he can get £1500 of the asking price of the the vehicles he is looking at and have this done... happy days. Do you have a link to the work they carry out ?

Good detective work Henry :thumbs: Can't answer your questions unfortunately except to say that I've learned something new in that any signs of failure might be detected at an oil change. Also worth bearing in mind is that the pre-face lift models are now moving out of the 9 year (or is it 10 year?) warranty coverage and that owners of such cars might want to consider this event (however remote) when setting aside maintenance finances. ~ Maxie

Hi Daniel, This is the blurb from Autofarm's website: Alternative repair solutions and tuning technology for your 996, 997, Cayman or Boxster engine, including capacity upgrades for all M96 & M97 engines. Whether you are a staunch air-cooled proponent or not, the water-cooled 'M96' engine that first appeared in late 1996 in the Boxster, and has subsequently been employed in both the 996 and 997, is a quite remarkable piece of Porsche engineering. Nevertheless there have been certain problems with it; increasing mechanical noise, oil leaks, failing intermediate shaft bearings, and most significantly, failure of cylinder liners, which up until now has required a full engine replacement. It has to be said however that engines with these problems represent only a very small proportion of the total units produced. Whilst engine replacement has been subsidised by the factory, this route can still be very expensive for the owner. For some time now, Autofarm has been investigating and carefully developing cost-effective methods of repair for such engine failures as an alternative to replacement. We are now able to announce a set of carefully engineered and tested solutions for all these problems – the Silsleeve cylinder replacement and the Intermediate Shaft and oil seal upgrade. This is their website: http://www.autofarm.co.uk/engines/water_cooled They are based in Oxfordshire. Hope this helps mate! :thumbs:

oh, and this is the blurb specific to the procedure from their site: INTERMEDIATE SHAFT FAILURE PREVENTION Now available exclusively to Autofarm here in the UK, this technology from LN Engineering in the U.S can upgrade your engines weak intermediate shaft with a stronger bearing and prevent the possible failure from occuring and potential large builds in the future. The bearing on the Intermediate Shaft (IMS) is considered to be a weak point of the M96 series engines featured in all 986 Boxster, 996 Carrera's and some early 997 Carrera's. When rebuilding an engine we replace the intermediate shaft as a whole with the latest 997 style shaft. This is a feature of all our modern engine rebuilds and partly how we get such excellent reliability. However, this is not very cost effective as a preventative measure as to replace the shaft the whole engine has to be dismantled and reassembled. With this kit developed by LN Engineering in the U.S we can replace the bearing with the engine in situ (on Boxsters and 2wd Carrera models) as easily as changing the clutch and flywheel. You could change these items at the same time to save on labour costs in the future. FULL PRICELIST & OPTIONS CAN BE DOWNLOADED HERE First we drain the oil and check it for metal debris and particles. This preventative measure cannot be carried out on a bearing that has already failed or is failing. We check inside the oil filter as well as the housing. Our fixed price job includes an oil and filter change. Where possible we will carry out the replacement with the engine still in the car. This isnt possible on 4WD models. Here we see the exposed IMS and crankshaft once the flywheel has been removed. Special tools are required to remove the flange and bearing housing without disturbing the engine internals. This picture shows the bearing puller attached ready for extraction. The new bearing is then carefully installed. The new bearing also includes an improved flange and seal. All done, the flywheel, clutch and gearbox can now be reinstalled.

Do you not think by now any engine that was going to fail, would have failed already ? :dont know:

Thanks mate..! But it would be horrendous if this happened all the same. It is a real crap shoot buying the 996, but as we all know, they are bloody excellent fun to drive.. especially when I'm chasing you and Spectraluk..! :floor: :bandit:

Hi Daniel, I asked them that. Their reply is that anything can 'go' at any time. A lot has to do with the way the car is driven, and the frequency of the car being used. I would think the less used cars that get heavily thrashed at the weekends may be more prone to wear and tear as the components have been sitting idle for a while, as opposed to being used consistently.. this is just IMO and is not a qualified mechanical diagnosis.. Service history has a lot to do with it though. If the engine has been properly maintained then of course it will help as all revolving components will give off site specific clues as to their operational capacity. These clues can get spotted earlier if there has been consistent examination of the engine. That all said, if my memory serves me correctly, they did mention higher mileage 996's as being the ones to watch - 80K plus. I just grin and bear it and hope nothing goes wrong! :bandit:

That's interesting, before now they all kept saying it was the pre 40K milers that had the tendency to let go. :chin: I'm with Daniel on this one. TB

Very interesting So does that mean their are no recorded engine failures/ issues if you have auto farm do the upgrade? £1400 dosnt seem that bad for the lifetime piece of mind if that's the case I only have OPC warranty just in case the engine goes T*ts up and that's £1200 a year plus all the servicing that you have to have though them . So the cars had nearly 5 k spent just on extending the warranty ? So far

Dude, this happened to me at £62k miles, so it's not necessarily a case that lower the mileage, the more chance it's already been hit by this problem. I can also tell you that there is no sign of pending breakage. I was doing 40 odd mph when mine went - and it was instant, no noises or issues, just went.

Wotcher buddy, My memory obviously does me a disservice, but put it this way, at 40 years old there's a lot more going wrong than my rear end bearing.. :floor: But how worrying is that? I thought you had the GT model?? Would you suggest it was worth it to do the procedure? :?:

Update is as follows, further to talking to them again: Mileage and service history is irrelevant. The cars that have been driven slowly are more likely to break, as they are designed to be driven fast on the autobahn all day, not for trips to Sainsburys (you can count me out of this one).. In a nutshell, Autofarm have advised it is a component problem. They consider this to be a wear and tear item, like tyres, not something that reasonably lasts the lifetime of the car. The part they replace it with is a 997 shaft, and an aftermarket (American made) bearing. That all said, 997 owners are not exempted from this as these guys have done work on failures in 1st and 2nd year 997's. They reckon the percentage likelihood of this part going wrong is 1%. That all said, now that I know this, the percentage of time spent thinking about this when far from home will be a lot more like 60% for me! As someone in the thread has observed, it is not a lot of money for peace of mind.. The final word: the joys of Porsche ownership outweigh the worries, drive em and drive em hard as that's why you bought a Porsche in the first place. :bandit:

Have a look at these: http://www.911uk.com/viewtopic.php?t=55279 http://www.911uk.com/viewtopic.php?t=55510 http://www.911uk.com/viewtopic.php?t=56573 http://www.911uk.com/viewtopic.php?t=56568

I have spent so many hours writing in different forums about this problem and responding to e-mails etc - that I simply don't have time to repeat it all here - however there will soon be a comprehensive editorial in a popular Porsche magazine covering all the issues and various options and suppliers. Suffice it to say that - in our opinion - and our experience of probably rebuilding more of these engines in the last 10 years than anyone else - there is no need to replace the bearing with a more expensive one. This is born out by the fact that say 95% last forever despite the cause of the problem affecting a few. In that time probably the car has several owners so the chance of you being affected reduces proportionally as well - in your ownership. That cause is the fitting of a seal to an initially grease filled bearing and the gradual seeping in of oil as the seal wears, the resulting washing out of the grease and the replacement with too little oil that then runs too hot and does not allow the steel wear particles to be washed away and collected by the filter and magnet. After about 60K - if it has not failed by then - the seal has worn some more and the rate of oil leaking in and out of the bearing increases and most then survive OK - proving that despite having a poor initial life while the process of grease and too little lubrication by oil takes place - the basic bearing is still OK in almost all cases thereafter. A new bearing fitted new without the seal is fed by cooler oil thrown in the vicinity by two chains running @ up to 40mph in an oil bath - so if an old one that has undergone that initial dodgy phase then runs ok from that lubrication source because the seal is a little less tight - running without a seal at all and receiving the full force of fresh clean oil from new is much better. Unfortunately the original spindle has a poor design for an "O" ring that weakens the shaft and can therefore snap. We have manufactured tools to allow their removal and replacement for years and provide a stronger spindle and our cost on average is around £400 less than Autofarm's advertised prices (I suppose because they supply a much more expensive bearing). There is nothing wrong with fitting a bearing that it of higher quality and cost than is needed - it just costs the customer more than we think is neccessary and ceramic bearings can hace fragility problems in use and when fitting. Our offering has proven 100% OK. Although the bearing and spindle can be replaced with the engine in the car (for which our charges start @ £800 + Vat as a sperate job - manual car) it is cheaper combined with a new clutch and/or flywheel or RMS 9as there is duplication of work). Special tools are needed to protect the crankcase and shaft when removing the bearing in the car (which we have) otherwise further damage can occur even to the main crakcase. Re-fitting the std spindle is a no-no because it strains the weak spindle when re-fitting the carrier and can crack it - so if your dealer undertakes this without a tool I advise not to do it. However the chance of your engine failing an IMS bearing is still very small indeed and since customers on our Lifetime Maintenance Plan (not copied from Vauxhall's recent claim of being the first to introduce something that can last a lifetime - but now in its tenth year) would only pay for the parts if one failed (not the labour for removing, stripping and rebuilding the engine) - customers on our plan would be better off to simply pay the modest monthly payments (of between £55 and £72/month + Vat - for 6K or 12K/year) - that also cover the full cost of all future services (parts and labour), and annual MOT and the labour cost for replacing failed items (including wear and tear items like brakes and clutches etc) - and if their IMS then did fail - paying for the parts to repair it would still be cheaper than trying to avoid the possibility uneccessarily - and a lot less expensive than the cost of a Porsche warranty (that anyway stops @ year 10). If an engine was repaired for an IMS failure under the plan - for a small extra cost other parts not associated with the failure can also be upgraded and replaced (like shells and chains etc) for a small extra parts cost while other modifications (like fitting cylinder restraining rings) includes some labour but only for that part of the machining job. Unlike Porsche's warranty we have no age, mileage or claim limit to our plan. More details in our buyers guide and also details of our IMS work and failures on our web site www.hartech.org (actually wrtten some year ago now and becoming out of date - but too busy fixing engines to update info - sorry). Baz