IMS bearing failure prevention

Hi Guys, Seeing as I am probably planning on a clutch next year, I thought it may be worth having the IMS bearings replaced. I noticed Autofarm do a pretty good deal for clutch and IMS bearing replacement as well as a service for 1550.00 + VAT. Bearing in mind my car is high mileage (>100k) do you think it's a good idea to have this done? The engine is quiet and has no visible leakage around the IMS area. I've been reading a lot of horror threads however on the potential failure of early watercooled engines and it's got me a little worried..... Thanks,

Never say never, but if its made it to 100k its probably a good one! I guess though , for the price, its a worthwhile upgrade for peace of mind, especially on a car that doesn;t qualify for a warranty. The number of engine failures can be worrying, but bear in mind all the other ones which are fine and don;t get reported on the internet - its all too easy to forget the 95% + of cars that aren't afflicted.

That is it I suppose, no one ever comes on a forum to say how great their car is going, only if there is an issue! That said, my daily driver has been fantastic, and being an MG it gets a lot of bad press, but (touch wood) the thing has been bullet proof, I make sure I post up after a substantial amount of mileage just to say how well it is still going as it makes a nice change! I've been reading so many articles on the 996 na block online, on various forums and sites, it's a very common subject and I am sure you guys get bored of hearing about it from new members, but it can sometimes be a little confusing knowing what to believe and what to do for the best after reading so much. I've also been looking for a definitive list of symptoms and it seems they vary too. As the 996 is very much going to be a hobby, I suppose you would call it an 'enthusiast' car being something I have wanted from an early age, it is something I am going to take very, very good care of, I want to take the time to make sure she stays in top condition, so if this really can be and is as much of an issue as people seem to say I think I will get it done to be sure. Just one quick question of a techy nature, I saw a video of a Boxster engine tapping away or 'knocking' on tickoever, when the clutch was depressed the sound went away, someone posted this as an RMS symptom, I would have thought that was the clutch release bearing rather than anything else? Thanks,

I would have a word with Barry (Baz) Hart at Hartech if you are concerned. He also retrofits IMS bearings. I recall reading his analysis of the situation somewhere, in which he says that the main cause of shaft failure is when the bearing breaks up. He attributes a lot of this to it being a sealed bearing, so oil from the crankcase can not get in, and it relies on the packed grease inside to provide lifetime lubrication. I think I am correct in saying that when they fit a new bearing they remove the seals to allow crankcase oil to lubricate it. I also recall him saying that after a long period the seals lose effectiveness anyway, and so they tend to be 'self-fixing'. Have a word with him, rather than rely on my memory, and report back if I got it right!

The general consensus seems to be that the sealed for life bearing can fail on the lip seal which allows oil (particularly if its the mobil 1 0W40) to enter the bearing and wash away the original lubricating grease. The substituted oil isnt as good a lubricant as the original grease , particularly as with a damaged seal the oil cannot escape easilly and so localised heating and bearing degredation takes place. In addition , the amount of oil in the bearing will vary depending on how easilly the oil gets past the seal and if the oil drains away when engine is stopped. Removing the seal or having a seal that has failed significantly increases the turn over of oil in the bearing , reducing the risk of localised heating and so reducing the wear rate. With a high mileage engine I would suggest the seal has probably degraded to a point where oil flows freely around the bearing anyway. There is also some suggestion that oil doesn't work well as a bearing lubricant in low speed applications where there is a high load , as found in this type of deep groove bearing. This may explain why cars that are driven harder seem to be less afflicted as the speed of the bearing is kept higher and oil splash in the sump and from the cam chain increases the lubrication of the bearing past the seal. . Deciding to spend 1000 on preventive maintenance is a difficult decision, you may decide alternatively to opt for the hartech warranty which will cover labour for such eventualities and provide free servicing as part of the policy. There are other issues that afflict this engine , including cylinder liner cracking and cam chain tensioner failure , not to mention RMS. A warranty is peace of mind to cover all these eventualities.

I typed a detailed response and my session timed out It was along the lines that Gavin @ Hartec is of the same opinion of you, and has said that the seal should all but be gone and that the bearing should be 'self fixing' in that at this point oil should be freely circulating. I have come to the conclusion though that at whatever point I get a new clutch fitted, the RMS and IMS will be taken care of at the same time for the sake of a few hundred pounds extra. Cheers,

Before you choose where to have the IMS bearing upgrade (when your clutch is replaced) may I suggest you check out the prices you will be charged bu whomever is offering the solution - as at present ours are I think about £400 less expensive than others. Baz

~Thanks Baz, not sure of the rules on this forum around such things but can you tell me how much for RMS / IMS and Clutch? The only issue is that you guys are about four hours away from me, could it all be done while I wait? Thanks, Steve

Careful guys - this will be breaching the forum rules of advertising if we are not careful. I suggest you pm each other. Regards