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Finally, IMS, is this the answer and ultimate closure.

The bearing doesn't fit through the hole on the final design. Hence why the engine has to be split to fit one.
 
Think someone posted a while back that all 'new' 996 engines (including the short blocks) had the revised design in.
 
wasz said:
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.
 
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
 
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.
 
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.
 
mavg said:
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.

Check my thread linked in my sig for pics of what is involved for most of this work.
 
Some slight misinformation here, the 3.4L engine with dual row and KS pistons has a significantly lower failure rate of bore scoring and IMS failure than the 3.6L engine with the Mahle pistons and single row bearing.

But there are 3.4L engines at the end of the production run of the 3.4L with single row IMS and Mahle pistons which makes this engine just as vulnerable as the 3.6L to both failures.

When Porsche switched isn't exactly clear but for sure if your engine was made in the 90s it has the more robust parts, but its over 20 years old and that in itself is an issue too, so can't do right from wrong when buying one of these cars.

The factory press fit of the IMS bearing has a lot to do with it's life expectancy too as the outer race can be deformed on a tightly fit bearing, as well as how often the car has been used or sat around in bad oil, how often its oil has been changed and just down right luck.

Chain whip also has a big part to play in this story and it seems the dual row tolerates this better as the load carrying capacity of the dual row is actually slightly lower than the single row believe it or not.

Removal of the bearing and replacement of it runs a risk of damage to the chain guides by moving the location of the chain slightly so yes removal of the seal on a healthy bearing is a good thing as it allows better lubrication to the moving parts of the bearing and this is never a negative thing.

But when you engage your brain a bit you'll realise they're all going to need a rebuild one day, so if it's working fine just enjoy it and think about rebuilding the motor one day. Because there's a lot a good specialist can do to really improve these motors.
 
:grin:
 
Great thread! I'm about to replace my bearing as I had some silver sparkles in the oil filter. The gearbox is removed and I'm about to order a bearing. My first thought was to source a new original type bearing and remove the outer seal. Cheap and it looks like consensus is that it will last a long time.

Then I stumbled upon this: http://shop.guldenbergracing.nl/996/ims-lager/guldenberg-hydrostatic-ims-bearing

It would be nice to hear opinions about this kit even though I guess no one has heard about it. It looks like a cross between DOF and IMS Solution. It lacks a IMS plug and spin on filter and the oil feed point is the same as DOF, otherwise it looks like a IMS Solution. Cheaper than IMS solution but more expensive than DOF.

Thoughts?
 
Hi

Looks like a great bit of kit, but I like your original solution better as long as you can get the old bearing out and in without causing any damage and correctly aligned.

All the best

Berni
 
How do you know it's the ims bearing that's created the metal in the filter>
 
I don't know where the metal comes from. However as I have a 2000 996 I don't even know if the car has a single or double row bearing. So I removed the gearbox and while I'm there I'll look at the bearing. And if I have come that far I guess I can replace it with a new bearing even if it looks ok, I must remove to find out what condition it is in. Then I can drive a few kilometres and check the filter again to see if it has improved anything. If I find more metal I will look for other sources.

That is my thoughts and plans, I'm already halfway there. A cheap new original bearing is a small investment to rule out the IMS bearing as the source of the tiny metal flakes. I'd like an IMS Solution but I find it too expensive.
 

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