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IMS solution for IMS anxiety? Opinions needed.

CarPlebs

Trainee
Joined
7 Mar 2021
Messages
88
*last update below*

Hi everybody,
I had a past forum post with regards to IMS diagnosis. After many hours of research, I came upon on an article from the Porsche Club of Canada called IMS anxiety, it is a remarkably interesting read (link below). To sum up my car which is a 997.1 2006, should depending on engine number have the stronger IMS bearing which has been known to have the least issues with failure (I saw somewhere around 1%). Now the suggested approach was the following (abbreviation);
- Drop the transmission, IMS Flange cover, if there is a leak remove the cover of the IMS
- Inspect the bearing for visible corrosion, movement of the bearing etc.
- If all is in speck upon visual inspection, then replace flange gasket.
In theory after the plastic piece is removed and given that there was a leak in the first place. This should ensure that oil lubricates the bearings.
I am curious to hear deMort's and all of your opinions on this. deMort, a quick question, did you experience a failure of the IMS on 997's 2006+?
Thanks!
Dick
https://pcaucr.org/ims-anxiety/
 
Is there a reason your worried about it? Are you getting leaks or noise?
 
Sounds like the first thing to do is check your engine number.

MC
 
MisterCorn said:
Sounds like the first thing to do is check your engine number.

MC

Do this, then stop worrying about the IMS.

I hope you haven't done too much reading on bore score!!
 
This is an area i tend to steer clear of to be honest .. passions run high with this issue and people have many different views on this .. i prefer not to end up in an argument on this subject with anyone as that's not why i come here .

As a one off i'll detail my experiences of this issue .. But .. i'm not discussing it further or getting into arguments as this is merely what i've seen over the years ..

I started at an OPC in feb of 04 .. i'm guessing it was about 6 months after that we started getting cars in with failed IMS bearings ..

The classic was the 13 mm nut had sheared off , timing had jumped and oil was pouring out .. we used to look under the car on the transporter .. see the oil pouring out and pretty much order an engine at the high point of these failing .

Its been a long time so my memory has faded somewhat but i would say over a period of 3 months we had about 1 every 3-4 days .

This lasted about 3 months then dropped off ... from nothing to a lot then back to a dribble .

The interesting thing i remember .. at the time the failures were on cars at about 40K miles .. even today if someone finds a very low mileage car below this milage i do wonder if the bearing will let go ... last saw one about 2 years ago .. new customer .. Boxster on 35K .. made me think but i didn't say anything .

Other than that period then there has been a trickle over the years .. not seen any this year .. i think maybe 1 or 2 last year .

So then .. my conclusion ..

Poor oil flow and they failed at 40 K .. after that .. say 60 K then your into a part failing that can happen with any part on any car .. perhaps a bit more likely due to the design of this but any that were going to fail due to the oil flow would have done so by now .

Unfortunately parts do fail on cars along with any item you by from washing machines to TV,s ..

YES i Know these are expensive cars and it shouldn't happen .. but it did .. thats down to Porsche and in the USA .. lawsuits etc .. that's not my area and not something i can comment on .. i say what i saw and a basic description of how i see the issue .

13mm nut and a small thread .. its just not strong enough and the oil flow issue was a major cause .. i " think " .. i'm no expert .

In or around 2006 we started to see a far larger nut on the ims .. we were never told about this .. we just started to see this on the new engines .

I personally have never seen the larger type fail .. hartech have but they are the experts here and i would bow to their knowledge .. i'm just a single mechanic .

The failure rate i would assume is pretty low .. to me porsche finally redesigned it and slipped it out .. considering the lawsuits then i can see why .

In short though .. if i talk to a customer that's paranoid his IMS is going to fail .. to the point he is scared to even drive the car .. and yes i've seen it a few times then i would say fit an aftermarket bearing if its only for peace of mind .

Again yes i know these can fail .. yes i can explain why they tend to .. not getting into that though .

You can do an inspection of these with flywheel off .. you can monitor the oil filter canister for shiny chrome flakes .. some people i know have had metal in the filter for a few years .. each service we reported it .. .. their opinion was if it blows it blows ..

Not sure what else i can add .. DFI engine and this is no longer an issue .. 2006 ish with larger nut and its a low chance .. pre 40K and i still consider it to be a higher chance with the smaller 13 mm nut design .
 
Personally I think the whole (mainly American) IMS paranoia is massively whipped up by people who manufacture the 'solution". I came into Porsche ownership fully aware of the risks and the attitude that if it goes, it goes and I'll start worrying about it then. If/when it does let go I'll get a bank loan and use it as an excuse to get a 3.9 conversion.

Oh and pretty much every Porsche tech I've spoken to has said exactly the same as deMort - it used to be a regular occurrence, it's pretty rare now.
 
Jamie said:
Personally I think the whole (mainly American) IMS paranoia is massively whipped up by people who manufacture the 'solution". I came into Porsche ownership fully aware of the risks and the attitude that if it goes, it goes and I'll start worrying about it then. If/when it does let go I'll get a bank loan and use it as an excuse to get a 3.9 conversion.

Oh and pretty much every Porsche tech I've spoken to has said exactly the same as deMort - it used to be a regular occurrence, it's pretty rare now.

Fully agree with you there, I will be making a series on this to demystify the whole topic on youtube. Nevertheless its now 10pm, I have just gotten from the mechanic.
 
deMort said:
This is an area i tend to steer clear of to be honest .. passions run high with this issue and people have many different views on this .. i prefer not to end up in an argument on this subject with anyone as that's not why i come here .

As a one off i'll detail my experiences of this issue .. But .. i'm not discussing it further or getting into arguments as this is merely what i've seen over the years ..

I started at an OPC in feb of 04 .. i'm guessing it was about 6 months after that we started getting cars in with failed IMS bearings ..

The classic was the 13 mm nut had sheared off , timing had jumped and oil was pouring out .. we used to look under the car on the transporter .. see the oil pouring out and pretty much order an engine at the high point of these failing .

Its been a long time so my memory has faded somewhat but i would say over a period of 3 months we had about 1 every 3-4 days .

This lasted about 3 months then dropped off ... from nothing to a lot then back to a dribble .

The interesting thing i remember .. at the time the failures were on cars at about 40K miles .. even today if someone finds a very low mileage car below this milage i do wonder if the bearing will let go ... last saw one about 2 years ago .. new customer .. Boxster on 35K .. made me think but i didn't say anything .

Other than that period then there has been a trickle over the years .. not seen any this year .. i think maybe 1 or 2 last year .

So then .. my conclusion ..

Poor oil flow and they failed at 40 K .. after that .. say 60 K then your into a part failing that can happen with any part on any car .. perhaps a bit more likely due to the design of this but any that were going to fail due to the oil flow would have done so by now .

Unfortunately parts do fail on cars along with any item you by from washing machines to TV,s ..

YES i Know these are expensive cars and it shouldn't happen .. but it did .. thats down to Porsche and in the USA .. lawsuits etc .. that's not my area and not something i can comment on .. i say what i saw and a basic description of how i see the issue .

13mm nut and a small thread .. its just not strong enough and the oil flow issue was a major cause .. i " think " .. i'm no expert .

In or around 2006 we started to see a far larger nut on the ims .. we were never told about this .. we just started to see this on the new engines .

I personally have never seen the larger type fail .. hartech have but they are the experts here and i would bow to their knowledge .. i'm just a single mechanic .

The failure rate i would assume is pretty low .. to me porsche finally redesigned it and slipped it out .. considering the lawsuits then i can see why .

In short though .. if i talk to a customer that's paranoid his IMS is going to fail .. to the point he is scared to even drive the car .. and yes i've seen it a few times then i would say fit an aftermarket bearing if its only for peace of mind .

Again yes i know these can fail .. yes i can explain why they tend to .. not getting into that though .

You can do an inspection of these with flywheel off .. you can monitor the oil filter canister for shiny chrome flakes .. some people i know have had metal in the filter for a few years .. each service we reported it .. .. their opinion was if it blows it blows ..

Not sure what else i can add .. DFI engine and this is no longer an issue .. 2006 ish with larger nut and its a low chance .. pre 40K and i still consider it to be a higher chance with the smaller 13 mm nut design .

Thank you very much for your honest feedback, it is very much appreciated. I have just gotten back from the mechanic we took the tranny off. However we did not have enough time to take off the flange cover. However as you can see in the picture it is in fact the IMS bearing that has been causing the leak. I can also confirm that it is the larger bearing (22mm bolt) and by the engine number. I will make a 2 part series on this to clarify on YouTube as in my searches I could not find that much in the 997.1 with the reinforced bearing.


Quick question, I know the engine needs to go out to replace the bearing if it turns out to be in crappy condition. After the engine is out how difficult would it be to replace the bearing? (p.s. just read its a. full engine rebuild :O)

edit: second question, does the timing need to be locked from your experience?

Thanks again!
 

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Boy am I glad I hadn't Iains knowledge when I bought my 996 c4s on 40k miles back in 2015. I had never heard of an ismb until after purchase. I would have been way too scared to thrash it across Europe as I did. Trouble free as it turned out, for 20k miles. My opinion? Drive and have fun and forget about the imsb!
Rick
 
segart said:
Boy am I glad I hadn't Iains knowledge when I bought my 996 c4s on 40k miles back in 2015. I had never heard of an ismb until after purchase. I would have been way too scared to thrash it across Europe as I did. Trouble free as it turned out, for 20k miles. My opinion? Drive and have fun and forget about the imsb!
Rick

Fully agree taking into account that the iMS is reinforced on the 997.1 2006+, now its purely on the inspection + replacing the seals so it does not leak in the garage.
 
Its my understanding that you cannot replace the larger bearing without splitting the engine because the flange is on the outer edge, on the earlier bearing engines the flange is on the inner edge so it can be removed engine in situ. My local Indy removes the inner seal to encourage better lubrication.
I think I probably have the earlier bearing, early 2005, but I gather you cant always be certain just by engine numbers. Bear in mind early bearings are the same size as the 996, I wonder what the failure rate is on these now, I'm guessing because people are more educated on prevention techniques, this might also help to explain a drop of in the incidences of failure.
At least if its leaking you know its getting lubricated!
 
All excellent contributions from others - just to add a few nuggets (although I agree that I should probably know better and it is a volatile polarising subject asking for trouble declaring an opinion on De-mort).

From all the ones we saw early on our conclusion was that the grease they were fitted with originally lasted a few thousand miles and while it was in the bearing IF it was a tight fitting bearing there was some debris worn off the tracks as they were "running in" that mixed with the grease to form something resembling grinding paste that quickly wore out the bearing and it could fail - often at very low mileages.

However those that were not too tight gradually allowed the grease to leak out (as it is thin when hot and the seals are not capable of lasting for ever) and then it was pot luck if the oil got in enough to lubricate the bearing or it ran dry soon afterwards.

Once the seals wore - if the internals of the bearing were still Ok enough oil lubricated them and they then lasted for a very long time indeed (as ball bearings need very little oil to run perfectly).

The early double row bearing produced double the wear particles as it ran - in and so the mixed grinding paste we observed was often worse so even though the bearing was stronger they still failed early on. However if they outlasted the first failure phase they often went on almost for ever.

Although there is a similar double row bearing available now there wasn't when they first started going wrong so we replaced them with a single row but took the seal out (because the oil level in the sump was high enough and anyway there is a chain flailing around up to 40 mph in the oil bath splattering oil everywhere). These lasted well with only one failure I can remember after about 22K and 2.5 years - the rest were OK, but we didn't like the whole design and decided it the bearing was basically too small for the application and should not have had the seals in place. We didn't offer their replacement as a service and left it to others among which were some roller bearings.

We saw the LN oil pressure fed solid bearing and thought it was such a good idea no need to compete and stocked it - but the cost put most UK customers off it.

We thought of roller bearings but we thought Standard roller bearings do not have enough axial load capacity to stand the results of chain whip for as long as many claimed but there are some special ones that do have reasonable axial load life that others used but they needed special design care on the end washers for lubrication to last well (which some applied). Instead - as we didn't want to enter the race for IMS replacement business (too busy rebuilding engines) we took the opportunity to make some new ends to fit to old shafts that carried a larger ball bearing (like the second version of the factory IMS bearing) and fitted them to rebuilt engines when requested or replaced the old small bearing Hivo shafts with Porsche ones.

Because the new Porsche IMS only matched to the Hivo chains we made another version of the new end piece with roller chain sprockets so both types could enjoy the larger bearing.

Now we are testing a different bearing set-up that is much stronger and has longer life expectancy than either the large Ball bearing or the best roller bearings and is more than adequate to resist both axial and radial loads which should be the ultimate answer.

Although the specification should mean they would never need replacing - it troubled us that these new tests were on bearings that could only ever be replaced by stripping the engines again - so we have now re-designed the application for one that we expect to be still much better than any existing bearings but that will be able to be replaced without stripping the engines and when this becomes available it will be able to be retrofitted to existing Porsche or Hartech large bearing shafts in situ (but not the older smaller bearing shafts for which we still think the LN solution designed by Jake Raby is excellent).

The problem with the original spindle was a very bad engineering decision to machine a sharp edges groove into it for an "O" ring which weakened it in fatigue mode.

More later if the current tests go well after which the new solution will be announced.

Meanwhile if the engine has survived for over 80K with the original bearing and it is not noisy - probably best left as it is because removal and re-fitting can damage the very housing it has been in for so long so the new replacement bearing fits tighter than the original (and often not roundly) and this can cause premature failure of the second bearing while the refitting process can damage chains and especially runners without extensive support tooling (which we made years ago) and a lot of care, if checking it exposed probably best to flick the outer seal off for better lubrication and cooling from splash oil.

Not going to enter into any arguments about the content of this post - a report with more complete and numerous pictures is free from [email protected] - ask for "report on the 4 main problems with these engines".

Picture of std small large and Hartech replacement re-manufactured shafts for the bigger bearing (not yet the new development versions).

Baz
 

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Thank you for answering .. you are the experts here and it's helped clarify a few items .. at best i can only give an overview .

I'm always open to anyone questioning me though as long as it's a 2 way discussion .. i don't claim to know everything and things like this are best left to the experts to explain but in the meantime i chip in with what little i know .

i'm all for learning when ever i can and i tend to learn with every post you make :thumb:


CarPlebs

Change the seals .. check for bearing play but after that perhaps leave it alone .

You don't have to drop the engine to replace these .. at least you don't with the smaller nut type , having never seen the larger type replaced then i don't have an answer here . .. you lock the cams , TDC then fit the tools to remove and refit with the smaller type though .

If a Tiptronic then yes you have to drop the engine .

My advice has always been .. if no play then leave well alone .. if scared to death then it has to be replaced ... replacement is a pulling tool and a press tool .. it serves a purpose but i'm not a huge fan of this .. without major cost though it is what it is .

LN seems to be one of the better ones but the cost is getting a bit silly now .
 
deMort said:
Thank you for answering .. you are the experts here and it's helped clarify a few items .. at best i can only give an overview .

I'm always open to anyone questioning me though as long as it's a 2 way discussion .. i don't claim to know everything and things like this are best left to the experts to explain but in the meantime i chip in with what little i know .

i'm all for learning when ever i can and i tend to learn with every post you make :thumb:


CarPlebs

Change the seals .. check for bearing play but after that perhaps leave it alone .

You don't have to drop the engine to replace these .. at least you don't with the smaller nut type , having never seen the larger type replaced then i don't have an answer here . .. you lock the cams , TDC then fit the tools to remove and refit with the smaller type though .

If a Tiptronic then yes you have to drop the engine .

My advice has always been .. if no play then leave well alone .. if scared to death then it has to be replaced ... replacement is a pulling tool and a press tool .. it serves a purpose but i'm not a huge fan of this .. without major cost though it is what it is .

LN seems to be one of the better ones but the cost is getting a bit silly now .

Thanks allot :worship: ! To change the seals is it necessary to lock the cams as well? over the weekend we might manage to take a look
 

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