I recently started looking for a 2002-04 996 C4S. Never owned a 911 before, so I started doing some internet research to see what issues to be aware of. I very quickly learned about the IMS issue, as well as the replacement and retrofit options from LNE. I'm still interested in finding a C4S, but I am leaning towards having the retrofit bearing installed, if only for peace of mind. I can't really justify an extra $10k for the turbo for what will be a weekend car, and frankly I think the C4S looks better than the turbo.

Anyway, I talked to several indy Porsche mechanics about doing a PPI (two of the shops were recommended on another Porsche board). I asked all of them if they did any kind of check for IMS issues (like looking for metal or plastic in the oil, or listening for rattling from the IMS bearing). Two of them had no idea what I was talking about. I explained the failure I had heard about, and one of them said he had never heard of that failure. Another said it is so rare that they don't worry about it.

So what gives? Is it a widespread problem, or do anecdotal incidents get blown out of proportion because of the internet? It clearly has happened to some 996's, but what are the real odds of encountering an IMS failure?

 

I don't think you or anyone else will get a definitive answer. Yes, there have been quite a few IMS blowups reported here and on a couple other forums. What is the percentage? Donno. LNE has probably seen the most as they produce the updated part and most people with IMS failure contact them. My personal shop specializes in porsches and he said he has only heard of 1 local car with a failure. My local dealer doesn't even know about the IMS failure. Regardless, IMS is a design failure and something that can happen to any car.
If you're worried about it, do a retrofit or just pass and go for the turbo. How are you going to enjoy the car when you're going to be worried about it?
Personally, I still have the factory original and redline it daily. It'll be a PITA but if it goes, it goes. Till then, I'm just going to enjoy.
Good luck on your search.

 

I talked to a Porsche Tech from Porsche USA tonight at a Club function and asked him specifically about this problem. He freely admitted that it happens... but rarely... and it can be attributed to over reving the engine and infrequent oil changes. I asked if there was any truth to the rumor that lightweight flywheels could be a cause for failure and he said that didn't cut it....

I then asked if he thought it would be a good idea to replace the bearing when replacing the clutch and he agreed for peace of mind that would be a good idea... again... and he stressed this... it has been infrequent....

 

These forums tend to over-inflate the issue....

Every car I have owned has had its own history of supposed "bad DNA" and this IMS problem just happens to be the "bug in the soup" for our cars. I would not worry but I would pay attention to my oil change cycles and consider changing the bearing whenever replacing the clutch.

Jason

 

Can't deny that IMS problems exist. Also, can't (and never will) know to what extent. I am, however, pretty sure that every single one that does exist winds up being discussed on these forums.

The 996 is a great SPORTS car that be driven every day. Name another SPORTS car that you say that about

 

..........IMS does occur, but I agree on the matter could be out of proportion due to several internet subjects around the case

My 911 (3,6 / 2002 / 68t kilometers) had a IMS failure 2 months ago - and is still at my local Porsche garage for repair

I have discussed the matter with Porsche Denmark and HQ in Porsche Germany. Porsche HQ will not recognize the IMS as being a general weakness on the engine (obvious!) but nevertheless they have continued in developing the bearing/IMS over the years...

In the time up to the breakdown of my engine I noticed no obvious sign of the bearing was to snap....

 

Lack of oil changes a cause of failure? Isn't the IMS sealed?

 

Thanks for all the perspectives. That actually helps quite a bit.

deckman - I'm no expert obviously, but from what I've read one theory is that moisture in the oil can cause the seal and bearings to deteriorate, leading to the failure. More frequent oil changes means less chance of moisture accumulation in the oil, which means less chance of failure, or so the theory goes. The moisture theory would also seem to be consistent with reports that the failures happen more often to garage queens than cars that are driven hard on a regular basis. But who knows. Whatever the cause, it would not be fun to experience in an out of warranty car.

 

I dunno. I had three leaks of my IMS (no failure though) before I sold my car. I changed the oil twice a year regardless of miles. I will always think it's just the luck of the draw and isn't dependent at all what the owner does or doesn't do.

JEllis is right, all performance cars have some form of an achilles heel. I have an M5, and the SMG transmission is discussed in the same way the IMS is here.

 

First of all, when it happens to you and you have to spend $16K for remanu engine, you are definitely going to let everybody know about it (ie bad news travels fast.) The smart thing is to NOT let the oil go 15K, like Porsche recommends. Change oil at least every 5K with a 5-40 oil and preferabbly not Mobil 1 (Castrol Syntec is good and approved) Mobil 1 does not contain the additives that Castrol Syntec does for protection. Always change the oil filter, LNE makes a quick change spin-on adapter which makes oil changes much easier. Tiptronics seems not to have the same incidence as manuals, but there is no proof to this. Some say not to baby the car, but be sensible and drive the car like a Porsche should be driven, hard but not abusive. Most of all, have fun in your new car and don't stress out about the IMS.

 

My thoughts on the IMS bearing is don't think about it until you have the trans out for a clutch or something else. Then spend the extra $700+ to put in the LN bearing upgrade. Fairly cheap peace of mind if you are already in there.

 

Dharn55 makes a good point. Should you loose sleep trying to avoid, or accept the inevitable upgrade the next time the trany is out.
During your pre-purchase inspection you can certainly ask to specifically check for the tells, such as a leak or give it a good listen with a stethoscope, , but I think you can also check the cam timing for wild deviations suggesting failure is imminent.

 

The three worst days of my life was waiting to get to the dealership after finding a puddle of oil on the garage floor on a Friday afternoon. Thank goodness it was just the RMS. Replacing the RMS with the PTFE one and new loctite bolts to the IMS made me much happier. Best of all was viewing and personally inspecting the IMS area. I agree with most readers here. Change the oil frequently and don't let it idle frequently, without taking it for a spin. Need to get the temp up to 180 degrees. I chose the 996 over the 997 for reasons many of us agree on . . . better design. For what it's worth the 996 is a great Porsche and like other super cars will have a mechanical problem at some point. Forums will produce "fear mongers" and make you doubt you Porsche and other things in life. Trust your instincts, get a reliable mechanic you can trust and drive drive drive.

 

my porsche dealer has done 7 in 6 months. if you read the threads you will see that this problem is not as infrequent as you are being led to believe. you can spend 2000 dollars and have piece of mind or spend 14 to 18 thousand when the bearing lets go. the problem is not infrequent oil changes but a design flaw in the bearing that porsche uses. if you go on lne website you can watch a video and they will explain ims failure.

 

Are you telling me, based on your Porsche dealership, that a 996 (1999-2004, excluding non-turbo/GT2) average one IMS failure per month and by these calculations have set the trend for all normally aspirated 996s throughout the United States and ROW? Yes. I have read the "threads" but with caution. Opinions can cause subjectivity which I was a victim to. Specifically, how many IMS versus RMS failures have there been? Committing to a 996 or any other exotic sports car is also a commitment(investment)to future costs. In a vehicle where tires cost over $1800 shouldn't we be aware that an engine repair/replacement could cost almost 10x as much? I love my Porsche. As a matter of fact . . . all 911s despite their mechanical flaws. I do believe that frequent oil changes, monitoring the IMS shaft and retrofitting it before the "breakdown" helps in maintaining a peaceful mindset. Engineering marvels always have there flaws. Just look around you and anticipate that it could happen to you. Just maybe. In the meantime, enjoy the ride.