Hello, new newbie alert and I have questions

[Robert SausageTrousers]

I'm by no means a mechanic and am here to learn as someone about to buy their first 911. I was under the impression that people fitted uprated IMS bearings to hopefully minimise the chances of failure.

 

[Phil 997]

The LN Engineering upgrade is the one most often used when guys talk of upgraded IMS

http://imsretrofit.com


https://lnengineering.com/products/...t-kit-for-my00-05-requires-tool-106-0822.html

or theres the direct oil feed option

http://www.tunersmotorsports.com/trs-development/ims-bearing-direct-oil-feed/

http://www.design911.co.uk/fu/prod1...ate-Shaft-Retrofit-Kit-for-Boxster-987---997/

https://www.youtube.com/watch?v=5xnVaMjaxGk


an interesting read on the same subject.
https://www.6speedonline.com/forums/997/262531-ims-failure-ln-engineering.html

https://www.pistonheads.com/gassing/topic.asp?t=1564383

 

[Alex]

And they've been ripped off. Hartech (best engine builders in the business) see after market 'upgrades' failing. What's the point of replacing something that has as much chance of failure as what's already in there?

The only robust solution is a bigger stronger bearing last seen in the 997.

 

[APL911]

Pish.

The only real solution is to have the IMS inspected.

If it is fine, then flip up the oil seal and leave it alone.

If it is not fine then get it changed for an OEM or LN engineering one.

My preference would be OEM by the way.

It has already been said that the OP has a dual row IMSB which are supposedly stronger and less prone to failure.

I am going to have my clutch and flywheel changed later in the year, when it is out I will have the IMSB inspected and will follow what I have written above.

If it fails in the mean time, I will have the engine rebuilt by hartech. However I expect upon inspection it will be fine. (fingers crossed)

I also agree with Alex that some of the aftermarket solutions look like total crap. The only one I would consider is the LN engineering one.

As an aside, you should check your oil regularly and check there are no fine metal particles in it. Make sure you follow the service plan, and change the oil atleast every 12 months.

This is all my personal opinion, but some of it is factual. :grin:

 

[Osh]

Just popped in to say :welcome:


Best newby username for quite some time, hope you stick around :thumb:

Aint that the truth! :grin:


Osh

 

[Phil 997]

The subject of IMS and Borescore are very immotive subjects as with all these things inc the upgrade IMS kits ,some may have failed but we really done know how the car was treated , was it a badly done DIY was it a car that was tracked really hard , what were the over revs has it been jammed down thought the gears with out this type of info to support these things its really difficult to say theres an issue with things like the LN kit and Hartech really should know better than to talk about it without knowing the full history of the cars use as all it does it create confussion.

All I know for sure is the 2 options in my previous post are widely and internationally accepted as a better option if you really feel you need to upgrade , there are also a huge amount of posts on forums that say if its done 60k plus remove the covers and leave well alone.

So all anyone can do is read the info and based on what they read make there dessision about which camp they fall info and do what makes them feel happy.
and remember these are just cars and any car of any marque can go rong at any time so nothing is ever 100% :thumb: :thumb:

 

[Robertb]

@Alex - As an engineer, what do you think of this IMS bearing?... to my unpracticed eye it seems to offer something different.

https://www.europeanpartssolution.com/ims-bearing-upgrade-kit/

Back on topic, my concern with the upgrades is that we don't have a proper statistical sample to see how they work over years and proper miles. The OE bearings are tried and tested in hundreds of thousands of cars for 20 yrs.

The more I think about it, its another reason to use 10w50 oil as this might provide better lube for the bearing than a thinner one.

 

[Osh]

I'm by no means a mechanic and am here to learn as someone about to buy their first 911. I was under the impression that people fitted uprated IMS bearings to hopefully minimise the chances of failure.

@Ragpicker - this one is a cracker, too... :grin:


Osh

 

[GMG]

...so, the Porsche specialist that has my 996 with a trashed bearing has another 996 and boxster with ims failure so anyone thinking that these issues are rare are frankly deluding themselves...if they dont fail then why are Hartech and other garages replacing so many?

They do fail and will fail...its a a demonstrable gamble with the odds stacked heavily against the owner!

I have sanctioned the rebuild and will arrange to replace a few other bits and bobs to future proof the car whilst the engine is out so whilst financially painful (thankfully not ruinous) now will be worth it in the longer term when I sell the car...swings and roundabouts...

My advice, for what it's worth, stands; if the bearing hasn't been changed;change it ; unless you fancy the looming threat of an £8 -10k bill?

But like anything in life, you pays your money you takes your choice...

 

[Phil 997]

@Alex - As an engineer, what do you think of this IMS bearing?... to my unpracticed eye it seems to offer something different.

https://www.europeanpartssolution.com/ims-bearing-upgrade-kit/

Back on topic, my concern with the upgrades is that we don't have a proper statistical sample to see how they work over years and proper miles. The OE bearings are tried and tested in hundreds of thousands of cars for 20 yrs.

The more I think about it, its another reason to use 10w50 oil as this might provide better lube for the bearing than a thinner one.

I am pretty sure this is the same kit as Design 911 sell as they are the UK distributor :thumb: :thumb:

 

[Osh]

...so, the Porsche specialist that has my 996 with a trashed bearing has another 996 and boxster with ims failure so anyone thinking that these issues are rare are frankly deluding themselves...if they dont fail then why are Hartech and other garages replacing so many?

They do fail and will fail...its a a demonstrable gamble with the odds stacked heavily against the owner!

I have sanctioned the rebuild and will arrange to replace a few other bits and bobs to future proof the car whilst the engine is out so whilst financially painful (thankfully not ruinous) now will be worth it in the longer term when I sell the car...swings and roundabouts...

My advice, for what it's worth, stands; if the bearing hasn't been changed;change it ; unless you fancy the looming threat of an £8 -10k bill?

But like anything in life, you pays your money you takes your choice...

GMG - do you know what percentage of 996's have failed because of this....??


Had my C4S now 3 years and its driving as strong as it ever has right now. Looking forward to stretching her legs while on the way to Dinslaken along with 30+ other cars from 911uk


Osh

 

[Alex]

@Alex - As an engineer, what do you think of this IMS bearing?... to my unpracticed eye it seems to offer something different.

https://www.europeanpartssolution.com/ims-bearing-upgrade-kit/

I'm in the same camp as Baz Hart (Hartech) on this one. The roller type bearing in this link doesn't take any side load like a ball bearing does and I wouldn't be too kean on fitting that. Also using a separate oil feed but using the oil in the engine could result in less oil pressure to other vital parts of the engine, so unless the oil feed is from a separate source, or modifications are made to the engine to allow the use of that feed, then I wouldn't be too kean on that either.

I think Baz covers mearly everything you need to know about IMS bearings in the 2 statements below:

I haven't time to read back through this whole contribution wither - and we haven't posted on this subject for a while because everyone seems to be getting the message - but I think to repeat our post of Dec 2015 achieves two things - firstly that not every specialist exploits concern to make exaggerated claims and secondly that the power of Internet Forums eventually allows a message to get across - amply described in the last post.

Just one additional statement I would like to convey and reinforce is that the larger IMS bearing in the later cars really is a solid reliable solution (especially with the outer seal removed).

In the years ahead many engines will need a rebuild anyway and it usually costs little different to wait for an early bearing to fail (or a liner to score or crack) and rebuild it with the best solution and may prove a better investment than trying to avoid the IMS bearing failure only to find the solution chosen didn't last that long or something else failed to require a rebuild anyway when the most reliable solution could be incorporated at the same time.

This is a relevant extract of what we posted last year:-

We are not only aware of all the types mentioned (thanks) but have seen most of them having failed.

The lateral loads on the IMS are not established but a ball bearing is designed to work both ways and with a splash oil supply and we have had discussions with a lifetime bearing manufacturing executive (who happened to spend a lot of time researching all the options and available bearings and owns a Boxster S) and he agreed that he thought it would need something better than a flat roller bearing end face (unless it also had a pressure oil feed) - but no one will have tested enough to destruction to confirm or deny anything - except that we receive and repair 4 to 5 engines/week (which has increased from around 2 to 3/week a few years ago) and I think the feedback this provides about the condition of original bearings, worn bearings and different IMS kits combined with our basic engineering knowledge is about as good a clue as to what the true situation is that anyone could provide.

You may remember (or can check back and find) that we were very unimpressed with a idea of a ceramic type many years ago (before they were in general use and known to fail) and have had two in here having failed in the last few weeks - I seem to remember we suggested they would be no better than the cheaper std bearing (possible worse?).

But you must appreciate (as we do) those specialists that try and provide solutions for problems that the manufacturer should have sorted out for their customers first. Usually spending money to genuinely try and find excellent solutions (and I do think they are more motivated by a belief in the success of their product and how it will help owners than doing it purely for commercial rewards) - but if the main manufacturer with a superb reputation can get it wrong - it is expecting a lot for most general technician specialists to find a better solution on much more limited funds in with far less test opportunities and resources. So I prefer not to knock those that don't always get it right while being frank about the difficulties some problems create that are often almost impossible to improve without huge expense and modifications.

The IMS bearing is a difficult problem to improve on in the space available without huge cost while the larger ball bearing seems (from all feedback and experience) to be totally reliable (and is available).

What to do will unfortunately always be a gamble and it is the odds that should influence decision making.

Unless there is an obvious reason to get into the smaller bearing in situ - I suggest it is a better bet to ignore it (or take the seal out if you are close by with the flywheel off and know what to do so you don't loose cam timing and can replace the outer carrier without straining the weak spindle).

If you were lucky enough to find the bearing damaged but having spread no debris anywhere - it must be worth carefully replacing the bearing and spindle.

We are reluctant to retail our replacement bearing, spacer and spindle kit because we suspect some owners will damage their engines trying to fit it (or have a premature failure later) but we will do so ourselves if requested - but without our usual cast iron guarantees. There are plenty of others now with their own kits that are prepared to fit them for their customers.

I think this whole range of cars are really superb - among the very best cars (on the whole) that Porsche ever produced and far less expensive than they would have been if the engines were more reliable - in fact - looked at in numbers - they represent superb buys with relatively little risk - and if you are unfortunate enough to suffer a failure - it is not too expensive to not only repair it but also improve those weak areas to result in an even better car that will appreciate in value.

It would seem to me to be a great shame to spend a lot on an apparent IMS "upgrade" only to find that later the engine needs rebuilding anyway and could have then been fitted with a much better solution for little more cost at the same time.

You must make allowances when I offer replies that sometimes I am referring to a theoretical issue someone has raised, or countering an incorrect technical conclusion or opinion and not always discussing what to do.

Unfortunately there is no good easy reliable permanent answer to the IMS small bearing issue without stripping and rebuilding the engine but plenty of good reliable and affordable "upgrades" if the engine is apart - as long as you also avoid those issues where some specialists do (probably out of ignorance or greed) promote a solution that has been proven to be short lived and often results in an engine requiring a second rebuild shortly after the first.

END OF REPEAT!

I think the above shows that we at least didn't try and exploit the situation and did try and provide well researched answers and that despite the often used accusations of "scare mongering" plodding on with accurate responses eventually achieves some understanding for readers that is useful to all.

The original double row bearing created more running in metallic particles to mix with the remaining grease and often lead to premature failure - but if they survived that and the seal was worn to allow oil to enter (as most remaining are old enough now to be) they often then managed to last very well and as most early failures were covered by warranties this may have influenced statistics taken later that mask the true picture.

Baz

Wow - what a subject for all to contribute their own particular info on and done to death over the years.

The early double row bearing was located with a snap spring ring that on removal with a puller can sometimes catch and damage the housing requiring a strip to replace the shaft. We have not had this problem but have had to rebuild a couple of engines that did - so it can happen - if rarely.

You can support the shaft with a machined out standard housing to maintain its position and use a sliding hammer to remove the bearing. This enables the spring ring to "jump" and clear the groove.

The problem is mainly in replacing it when you have to tap it beck in and this allows the shaft to move further in and can damage the plastic chain runner guide tracks.

The inner seal - as it wear - allows a small amount of oil to enter the inside of the IMs tube where it sits for years - only getting out when you remove the original bearing.

The original double row bearing was a special and I have not managed to obtain load ratings for it but it is not as high as two single row bearings (i.e. not twice the single load rating) because with the groove dimensions reduced it is more like somewhere between a double row self aligning bearing and two single rows side by side - at a guess probably more like 20 to 40% better load rating. A narrower double row bearing of same overall dimensions had a load rating some 25% less than a single row due to this reduction in groove dimensions.

The problem is that the original bearings trapped the fine small "running in" particles of metal that mixed with the grease for form a very fine grinding paste. We were lucky to find two over the years that still had grease inside and the grey colour with fine metal particle inside. The double row would reasonably be expected to create more particles than a single row and run hotter as a result and so we concluded that the early double row failures were more due to trapped debris than load rating.

The larger 6305 bearing that replaced the 6204 single row rates at 77% better load rating - so compared to the non standard double row bearing is possibly 50% better.

The video referred to is IMHO misleading because a ball bearing requires minute amounts of oil to run perfectly (as a previous contributor correctly described) and although the outside of the bearing is rotating - not only is it under the oil level of the sump but when running all the oil inside the engine is being churned around and creates a mist (which is ideal to lubricate a ball bearing) and right next door to the bearing is a sprocket or hivo gear of much larger diameter running at the same speed but churning up oil and throwing it around with much greater force than the bearing is forcing it out with. Add to that the chain running at up to 40 mph in the oil bath and you get some idea of how perfectly adequate the spray oil supply is without the seal in place.

When the dual row bearings first failed (at relatively low mileages) we managed to obtain the remaining stock of the special bearings from the manufacturer and fitted those to customer engines until the supply ran out.

when they ran out - we concluded that the next best then was a single row bearing (which we fitted with a spacer and a stronger central shaft) which was later supplied as standard by Porsche in later engines. 8 years ago we may not have recorded the specification of the bearing we fitted then but it will have had the seal removed and therefore either way should be acceptably reliable.

We have since had to rebuild engines for IMS failure of various types and concluded that basically the space for the bearing was too small and the bearing under-spec'd and therefore even with spray lubrication - may not outlast the engine. However IMS bearing failure is a very low number compared to cracked and scored cylinders meaning you are much more likely to have your engine stripped to repair those failures than an IMS bearing failure and therefore can change the shaft for one with the larger ball bearing at the same time - which is the perfect solution - especially with the outer seal removed.

So Hivo cam-chain drive cars could fit the Porsche larger bearing shaft during a rebuild and we have manufactured our own re-manufactured shafts for both Hivo and roller chain crankshafts with that larger bearing. In doing so we have plugged the inner IMS tube so old oil cannot enter it or interfere with the lubrication system - but this can only be fitted during a rebuild.

The small number of IMS failures now reflects that most small bearing engines have done enough miles to allow fresh oil to enter and exit the bearing and keep it going for much longer.

A plain bearing is ultimately going to provide better life expectancy but requires a continual supply of fresh oil - potentially robbing oil supply from other vital engine parts on hot tickover where the rather crude standard oil pump supply is poor.

If an engine has throughout its life been driven modestly - and the original bearing has survived - then removing the seal will probably provide the best overall outcome at minimal cost.

If the engine has been used spiritedly then cracked or scored cylinders, worn crankshaft shells etc may well be the first reason it may need a rebuild during which time the best solution is the larger ball bearing.

Weighing all this up - unless the existing smaller bearing is showing definite signs of wear - I would recommend removing the seal and awaiting a long life with it or a rebuild for other reasons rather than possibly waste money on a solution that may well not be any better and also find the engine needed stripping and rebuilding later on anyway for another failure reason.

With care - replacing it with a newer bearing of the same specification is going to work most often but if one failure occurred just after a business fitted such a replacement bearing and they felt obliged to repair the damage FOC - they would need to fit hundreds if not thousands of bearings successfully to pay for that one failure - so it is a risky business (unless the business involved would simply not cover such an eventuality anyway and expect the customer to pay for the rebuild) and "YES" we have been involved later on in fixing a few engines where just such a failure has occurred (often with litigation between the owner and the original bearing replacer resulting in some compensation) hence our own caution at offering such a solution when we would honour our obligations to our customers.

So a complicated situation not brought about by the independent businesses trying to help. Respect to those coming up with what they believe to be viable solutions - caution to others over the whole situation.

If you are considering an "upgrade" (which in reality is unlikely to be any better than a simple replacement) it is usually because you intend to keep the car for many years and as such the chances of also needing a rebuild along the way are quite high - when you can solve the problem with the larger bearing - so if you are considering saving for a rebuild one day anyway - why waste money on a short term solution that might not work anyway our outlast the rest of the engine?

Any replacement carefully fitted will probably be a bit better than the original - but is it worth the risk and expense - taking everything into account?

Baz

I think Baz's response to all this would be - "I'd be more more concerned about bore scoring than your IMS".

Wish I could come up with a £1k snake oil solution for that........I'd be in the Bahamas now, led on a beach, getting my d*** ****ed!

 

[Alex]

...so, the Porsche specialist that has my 996 with a trashed bearing has another 996 and boxster with ims failure so anyone thinking that these issues are rare are frankly deluding themselves...if they dont fail then why are Hartech and other garages replacing so many?

GMG - do you know what percentage of 996's have failed because of this....??



Osh

He doesn't know his has failed yet Osh.......it's merely an assumption by his garage.

And you know what assume does.........makes an ass out of u & me

 

[Bluebird911]

Oh no, not another IMSB thread!!

OP, As phil997 said, IMSB threads, along with oil threads, tyre threads and arguments about bringing up children, often get quite heated.

I think the thread started by Niall996 (and is a sticky) is very informative as he wouldn't accept comments unless they came with underpinning proof to get to the heart of the matter. He really wanted to get to the facts!

http://911uk.com/viewtopic.php?t=108257

Alex, if you are exchanging clichés, there are Lies, damned lies and statistics!!

You put a lot of effort (for which we are grateful) into gathering IMSB failure data to quantify the risk of IMSB failure and as you say, very few were reported (I think you said none), but your sample is tiny when compared to the many thousands of 996s and Boxster / Caymans out there.

From memory though, I don't recall Baz being critical of the many IMSB solution/upgrades out there.

OP, hopefully the info in this and Nial996's threads will help inform you come to you own conclusion.

 

[Alex]

Baz's comment was taken from Niall's thread and also this one: http://www.911uk.com/viewtopic.php?t=110445&start=27

Sample size is irrelevant. It's the results of the sample size that are.

3% of 120 cars is same as 3% of 12,000 cars.......it's 3%