Joined: 08 Nov 2008 Posts: 30194 Location: Hertfordshire and Hampshire
Posted: Tue Jan 31, 2017 2:14 pm Post subject:
On the basis I would to prefer an old and presumably worn (possibly critically) IMSB to be replaced with a new IMSB, I would strip both seals prior to fitting (it makes no sense not to).
In terms of the space behind the IMSB, every extra bit of "headroom" would improve the prospects of genuine turbulent IMSB wash.
For general reference, here is photo of single-row ex seals:
And although my previous description may have sounded off the cuff, I do agree the mod is NOT for the DIYer to attempt (not least the cost of the proper tools required for insertion and correct refit outweigh the labour savings)
If time was of the essence, then yes, only pulling the outer seal is better than pulling no seals!
Joined: 20 Dec 2008 Posts: 500 Location: Yorkshire
Posted: Fri Feb 02, 2018 2:23 pm Post subject:
What a thread!
I've been away from Porsche for a while but the car still waits patiently for use and attention. That time has now arrived. My IMS bearing was inspected when my clutch was done @ 15 - 20k miles ago (cars on 85k now) when the IMS cover was changed. The local and trusted Indie said it was fine. After reading this thread end to end - and I did, sort of puts things into perspective mostly the input from Baz.
My view is if it reaches 100K then anything after that is a bonus and a rebuild is due anyway due to natural wear and tear. No guesses for where I would have the unit rebuilt.
Baz's statement should go down in Porsche history.
It's been a few years since I drove the car, now where's the rear window washer switch? _________________ 996 C2 Manual
Arctic Silver
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Paul911c4 Newbie
Joined: 08 Sep 2017 Posts: 24
Posted: Mon Sep 03, 2018 10:10 pm Post subject:
So i got a 99 3.4 which will have double row its at 72000 miles ...
So its going to blow up or not ? How much to get a independent to pull off front dust cover ?
alex yates Le Mans
Joined: 06 Mar 2014 Posts: 15246 Location: The Ribble Valley, Lancashire
If its a manual wait till you have a clutch change. Should only be an hour or so on top. _________________ 2000 Manual 996 C4 Arctic Silver Convertible
infrasilver Fast & Furious
Joined: 04 Oct 2010 Posts: 8071 Location: East Midlands
While this thread has been resurrected I thought it a good place to mention something I saw over the weekend on the Porsche stand at the Festival of Porsche.
Among all the Drivers Selection clothing and usual tat, they had a short engine M96 on show, I was obviously curious as this is my kind of thing. When looking at the IMSB I noticed that this genuine supplied short block had some kind of uprated IMS.
The bearing post is the same thicker type as the Hartech one that is in mine and the nut, that was fairly basic before is now a lot larger and is a flange nut spreading over most of the bearing cover face. I wonder if this is the larger bearing too?
Dam , Infra how do we find out , I now want to know if Porsche have fixed a problem they wouldnt admit they had and if the uprated part is available to buy seperatly and if so how does the price compare with the known aftermarket fixes _________________ 911 Owners,Some Invest In The Future,
Others Enjoy The Moment Today.
My car has a 2010 manufactured 3.4 engine, this has the non serviceable style last design IMS so they have incorporate changes into replacement engines. _________________ 1999 C2 Coupe - http://911uk.com/viewtopic.php?t=124107
2000 Audi B5 RS4
The bearing doesn't fit through the hole on the final design. Hence why the engine has to be split to fit one. _________________ 2000 Manual 996 C4 Arctic Silver Convertible
alex yates Le Mans
Joined: 06 Mar 2014 Posts: 15246 Location: The Ribble Valley, Lancashire
Think someone posted a while back that all 'new' 996 engines (including the short blocks) had the revised design in. _________________ 2000 Manual 996 C4 Arctic Silver Convertible
infrasilver Fast & Furious
Joined: 04 Oct 2010 Posts: 8071 Location: East Midlands
Looks to me like they decided the centre pin is the thing that needed beefing up. A bearing with a larger centre with the same size outer means the balls are smaller.
The thicker centre pin is something I have had in mine for around 5 years, fitted by Hartech and the IMS cover hole is the same diameter for both but the thinner bearing post is only thinner where it has the waisted section for the O ring and the threads, this is also the weak point of the original design. The centre of the bearing stays the same diameter ie you can use both posts, thinner original and thicker upgrade with the original bearing. With the thicker post you don't have room for an O ring though.
If you hear what sounds like metal in a washing machine (think roulette wheel), the end of the post has snapped off with the nut, shut off immediately. _________________ http://euroroadtripper.blogspot.co.uk/
mavg Newbie
Joined: 24 Nov 2018 Posts: 15
Posted: Sun Jan 13, 2019 11:12 pm Post subject:
I am probably going to change my clutch as my 2019 maintenance schedule to keep the car top notch. I currently drive a 1999 (nov) with 80k miles.
What is the current "best in class" consensus replacement for the IMS? Direct oil feed? LN or Flat six or something else? I know well worth doing the RMS at the same time.
Are people pro-actively looking into flywheel when replacing the clutch?
Lastly if I may what is the view on the low temperature thermostat? I have seen my car had the oil separator replaced in 2017 so not needed at this point.
I had also read people changing the water pump when doing this bigger service, saves much labour time?
Still love the car every minute, thanks all
alex yates Le Mans
Joined: 06 Mar 2014 Posts: 15246 Location: The Ribble Valley, Lancashire
The best option on a '99 3.4 C4 is to remove the outer seal from the bearing fitted. You can check if there is any play in the bearing but I doubt there will be. Once the seal is removed, bolt back together, let fresh engine oil lubricate the bearing and forget about it.
Any after market alternative bearing that fits your ims is no better than what you currently have.......some may say any after-market is inferior. _________________ 2000 Manual 996 C4 Arctic Silver Convertible
alex yates Le Mans
Joined: 06 Mar 2014 Posts: 15246 Location: The Ribble Valley, Lancashire
Leave the RMS alone if it's not leaking........and personally I wouldn't bother with a LTT on a 3.4, only the bigger engines that score bores. _________________ 2000 Manual 996 C4 Arctic Silver Convertible
I am probably going to change my clutch as my 2019 maintenance schedule to keep the car top notch. I currently drive a 1999 (nov) with 80k miles.
What is the current "best in class" consensus replacement for the IMS? Direct oil feed? LN or Flat six or something else? I know well worth doing the RMS at the same time.
Are people pro-actively looking into flywheel when replacing the clutch?
Lastly if I may what is the view on the low temperature thermostat? I have seen my car had the oil separator replaced in 2017 so not needed at this point.
I had also read people changing the water pump when doing this bigger service, saves much labour time?
Still love the car every minute, thanks all
IMHO:
1) Is the clutch slipping or noisy? no need to change otherwise...
2) Best thing to do with the IMS bearing is leave it in place, flip the outer seal off so a bit of oil can flow through it. The 3.4 has a minuscule failure rate compared to the 3.6's small failure rate. Leave the RMS alone unless leaking.
3) I replaced my flywheel as it was grooved and felt a bit loose but still passed the test. Yours is likely fine at just 80k.
4) LTT is more important for a 3.6 where reduced temps can help stave off bore scoring, a 3.4 is more durable so I think its not necessary. That said it will not do any harm apart from slight increase in fuel consumption - I run one.
5) Water pump is probably a good shout at that mileage if never done before, to save it going at an inconvenient time.
At 80k and 20yrs it is an old engine, there loads of things that could go wrong, no point in addressing just the IMS Bearing when the 3.4 has a very very low rate of failure, and there is a risk of damage when replacing it in situ.
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and if so how does the price compare with the known aftermarket fixes 
