IMS Bearing. To Change or Not To Change (Hear me out)

Firstly, apologies, I know this has been done to death, but I'd appreciate your expert opinions. Although this is for 2000 Boxster 3.2, I'm posting hear as there is far mor traffic. We bought the car last year from a classic car auction as a bit of a project for me and my son. Reasonable condition with 123k and a fair amount of paperwork (including the original sales invoice). Drove quite well, but a very slight hesitation towards the top end. First things first, we gave it a full service and was going to a clutch and flywheel Change. When we dropped the sump, we were greeted by plastic pieces in the pan and a trainer clogged with beads of sealant. Pulled 1-3 cam cover off and the tensioner pads were well worn, but ultimately in one piece so put a camera down the chain case and saw that the IMS tensioner paddle was in a bad way. Some pictures on Instagram and you tube under Boxstclever. So, I'm now balls deep into a rebuild (my first, so be gentle). It's fair to say that the car has had some neglect in the oil change department as it was extremely brown and sludgy, but on the other hand has had a gentle life as bearing, crank and cam wear is minimal. To the point then! It's on the original dual row IMS bearing which is buttery smooth with no play. If we weren't going so deep into it, I would have popped the outer seal and left it, but with a full strip enters the conundrum. Leave well alone or replace as it's all pulled apart anyway. If I were to replace, I would want to source an original (or as close with a packing washer). I don't want to go to the expense of an LN for no real gain, and the Pelican parts one will be a single row. IF I do replace the bearing, I'd want to update the bolt, but can't buy this separately. I suppose I could buy the Pelican parts kit, use the bolt and buy a dual row bearing? BUT the existing one is lovely and smooth BUT has 123k on it. See my point? Lots of options, but would appreciate others opinions. P.s. anyone got new engine parts they want to get rid of? Thanks in advance guys.

Have you considered talking to Hartech about upgrading to the larger bearing IMS? I assume you are doing bearings whilst you are in there? What parts are you after? MC

If you don't change it you will constantly thinking about it for the whole rebuild AND when you drive it. I know it's extra work but if it was me I would do it for piece of mind. Having it apart and not doing the one thing everyone loves to talk about would keep me up at night :grin:

If the bearing has no play/wear in it then I'd just remove the seal and leave it be. To me that's a safer bet than pressing a new bearing in that may be a slightly tighter fit and could either create lapping paste bedding in or worse case fail. You have a perfectly good bearing there that you know has already done its job perfectly without and degradation. Why would you want to go from a minimal risk position to a higher one? Also, can you even get a dual row replacement? Didn't think you could to that spec. :dont know: That would be my preferable option (coming from a 33 year Engineering background). The only other viable option would be to fit the latter larger 997 bearing and get the parts manufactured to incorporate this into your IMS. Like Mistercorn states - Hartech may probably be able to assist or supply you with this. Just FYI: I dropped my gearbox back in may and checked my original bearing (seal removed) and it was still like new at 148k.

What would you replace it with?

Thanks for the replies so far. Much appreciated. I'm going to replace pretty much everything. Bearings, bolts, gaskets, valve stem seals....

I would go down the Hartech option as mentioned. Depends on location and if this was possible. However my comment wasn't really engineering based, it was more mental and how it could play on your mind and possibly spoil your Porsche experience. Things like that play on my mind, sometimes I'm right, sometimes I wish I didn't have an OCD affliction and I'd just left it well alone :grin: I wasn't aware there was an increased risk by touching it though? I suppose that depends on what options you take.

You're replacing a very known (123k miles) good bearing with an unknown bearing. If said bearing had any signs of play then it'd be a different conversation, but as it appears to have no or very very minimal play and you're now in a position to allow the engine oil to lubricate it, then IMHO, it'll outlast most other parts on the car.

...if it were me I leave the original bearing alone unless you are splitting the case in which case I'd install the new upgraded bearing... And this is advice from someone whom would have benefited from changing his single row bearing that shat itself !

If it were me I would be thinking about how long i wanted to keep the car and how many miles i intended to do. Being a 20 year old car a partial rebuild might not add any value to the car if you wanted to sell it at a later date therefore as has been said if the IMS feels ok then leave it alone. However since you are already in there, and providing the replacement bearing is inexpensive (not a word often used in conjunction with Porsche) then do it, especially if it makes you feel better. But where will is stop, what about rings...ends..main............................. :dont know: Good luck as i will be rebuilding mine when the weather warms up a bit.

On piston heads there is a thread about a 300k mile early 996 C4, run by an F1 engineer. Pretty sure he changed the double row bearing when his engine was rebuilt, but cannot remember what to? Its a long very interesting thread but lots of pictures so you can probably skip to the engine bit. Author is called Poppopbangbang so you could also skip to his posts rather than reading all the replies. Last time I read it he was looking into a KERS set up and carbon fibre wings.

You don't need to go to PH he's on here: See -> http://911uk.com/viewtopic.php?t=112106&start=0&postdays=0&postorder=asc&highlight= Use the same username to Search for his other posts.

His engine rebuild & IMS info is here: http://911uk.com/viewtopic.php?t=120095

See, this is the thing. Case is split. I'm doing shells rings, the lot, but the trepidation is the IMS. It's a known good dual row bearing. If I do replace I don't really want to put a single row in. I also have to weigh up the cost. I don't want to chuck thousands. It will be used and probably kept for a while or longer depending on the wife's thoughts on it. She'll be using it mainly.

You have to change it. You cannot go that far and leave that item off.