Seal removal on Dual Row IMSB
 

After much time I have finally decided not to replace my IMS bearing even though I am replacing clutch/flywheel and RMS.
Mine has the dual row bearing with very low failure rates and I don't want to replace what I think might be a perfectly good bearing. I just don't like the idea of messing about with something and potentially creating more problems.
I will however remove the flange and have a look at it (and replace the bearing if it appears to be about to fail) and I would like to remove the outer seal to allow better oil flow. Flange seal to be replaced too.
Baz from Hartech posted a good essay on his thoughts and I agree with what he says but he goes into some detail about removing the seal here and I am not totally sure what this means...

Removing the outer seal of an existing bearing is a good option (if the existing bearing seems OK) and the only danger then is to make sure the spindle is not strained when aligning the out spider carrier back into the location hole. This spindle has a weak spot where an "O" ring is fitted and is it unfortunate that at precisely the point that the spider fits on to the spindle the outer diameter of the spider fits into its location hole and both need the IMS to be pulled sideways to pull against the chain tension (even with the tensioners relaxed) to locate both in their respective holes.

Has anyone done this?

This is the whole thread on Pistonheads. https://www.pistonheads.com/gassing/topic.asp?t=1564383

Many times.

He is refering the the center bolt which he calls the "spindle", and he calls the flange cover a "spider carrier". The factory center bolt has a rather severe undercut which is where the bolt oring sits. It is also the most likely point where the factory center bolt fails, so he is telling you to be careful with it. The LN bearings come with a completely different center bolt specifically to address this weakness.

If you have a flange bolt that is of suspect design for my money you replace the bearing, put in the latest technology in flange bolts and as long as you have gone that far incorporate direct oil feed. I just replaced my double row IMS on my 2000 S. The bearing I took out was, as it turns out, in good shape. Nevertheless, I put in a new double row bearing, new flange bolt and direct oil feed. It seems you either go that direction or just leave the whole thing alone and hope for the best.

So pulling the flange off to replace the seal is not as easy as it sounds?
I would leave the whole thing alone but because my RMS has sprayed oil everywhere I don't know if the IMS flange is leaking too...I suspect it is, but not nearly as much as the RMS.

For me the whole IMS thing is blown way out of proportion, there are lots more ways an engine can fail other than that bearing..a broken cam chain would do the same..but for me I have snapped off 8 of the 12 header bolts removing the exhaust system to change the RMS.
I had to take the headers off because the 3 bolts at the next join were non existent and no way of drilling out what was left of them. I nearly scrapped the car because of these and they are not something mentioned regularly.
In the UK, my car a 99 2.7 70k miles full PSH 1 owner, perfect condition is worth about £5k. A dealer offered me £3k p/ex because of the oil leak from the RMS.
Here she is..£5k!https://serving.photos.photobox.com/...8a00908f00.jpg

In order to pull the flange and get at the seal, the engine has to be prepped as though you were going to pull and replace the IMS bearing( locked at TDC, cams locked, tensioners pulled, etc.).

I went ahead and ordered a complete tool kit from a company that make them in Sheffield for £100. Stainless steel too.

https://www.i6automotive.co.uk/workshop-tools/porsche-ims-bearing-removal-puller-tool.html

I figure I can sell it afterwards and get most of the money back.
Cover will be off soon so I can have a look at the bearing and make a decision. If it's firm and solid I'll pul the outer seal off, if it's wobbly at all I'll replace it, LN or EPS , I haven't decided yet.

I'm no expert in this matter, but a visual, although better than nothing, will only tell you so much. And I think you'll be only able to tell only if there is extreme wobble/wear. Inspecting the oil filter for magnetic metallic flakes is probably going to tell you more too...

I have a factory reman 2006 3.2 with the big bearing and can not replace it easily, so I pulled the outer seal for better lubrication. Then again, I drive that car hard, and I don't worry too much about it.:cheers:

My IMS removal kit arrived today, it looks good but I don't think the cam lock is going in the slot in the cam properly. Does anyone know the actual width of the slot in the cam and whether it's a square slot or tapered.? Mine is a 5 chain engine so only 1 slot.
Same for the bank on the right... the steel plate they are made from is 6mm thick.
Do I need to lock both side?

So I removed the flywheel and there was some oil spread about the rear of the engine, some had gone out the gaps in the bell housing and covered the right rear of the engine.
https://serving.photos.photobox.com/...5fcd4861fa.jpg

https://serving.photos.photobox.com/...b9b1505213.jpg

Not really obvious if the IMSB flange seal was leaking but I reckon it might have been weeping. The RMS oil must fling out when the engine is running and spread everywhere.
https://serving.photos.photobox.com/...319acc354e.jpg
Cleaned it all up.

So I locked up the cams after modifying the tools I got. Pulled the tensioners and pulled the flange.
As I thought the bearing looks perfect with no movement on it whatsoever...It looks like it was just fitted. Dual row.

https://serving.photos.photobox.com/...edd8c5a352.jpg

https://serving.photos.photobox.com/...5121ff079d.jpg

So now I'm thinking leave it in, get a new type flange from Porsche and fit new clutch/flywheel, RMS ..job done....right?
Well I just don't know what the races/balls are like.probably like new no doubt.
Need to make a decision.

Troutman, must be easy to spend some body else's money, but if I were on your position I would definitely buy a new dual row bearing from LN Engineering, because if your IMS bearing fails you will have to do it all over again (IF the engine is salvageable..)

Good luck with your project!

You spent all the time and effort to get at it because you were concerened, so it makes no sense to just leave it there as you are now about 10 min. from pulling it and replacing it with something that you can forget about for a long, long time. Choice is yours............

Not exactly..I did all this to replace the RMS and stop oil being thrown everywhere. In the UK oil leaks are recorded on your MOT (online for everyone to see) as well as any other concerns the tester has with your car.
It's hard to sell a Porsche with an oil leak , registered on the internet.
The IMSB was always going to be an inspection first approach.

I know what you mean though...it's the £700 that gets me, when a new Sachs clutch and LUK DMF is £490...if it was say £200, no problem.I definitely am not replacing this dual row with a new single row, just doesn't make sense at all.
I might go down the EPS route.

You would be better off to leave your factory bearing in place.

When I pulled the seal off my dual-row bearing I found no grease at all -
Only the oil that had found its way past the seal.

The question that no one can answer is how long will the bearing last if you leave it as is?

I decided to pull the bearing and replace it with the Pelican Parts kit. Yes, it's a single row bearing, but that wasn't a concern because I'll be replacing mine regularly. It's a maintenance item.

The other thing the Pelican kit gives you is the upgraded 'bolt'. The factory one has that cutout for the o-ring. When you see it in person you can see why this design is prone to failure.

Lots of ways to blow up your M96. I found a used 2.5 for $1000 and I keep it tucked away just in case. I sleep really well at night now.

Good luck with whatever you decide.

I don't think you're going to replace that bearing regularly are you? It's not a set of brake pads.

For instance my 2.7 has circa 80k on it and it's 19 years old..still on the original bearing and clutch/flywheel, I know this because I have a FPSH from the PO. RMS was changed in 2000 under warranty.
Changing the bearing is not something to be taken lightly, it's a big expensive job and it can cause other problems bashing a new bearing into that precision part called an IMS.

On a car that's worth £5k I'm struggling to justify replacing what appears (and I know what that means) to be a perfectly good bearing with another product for £700 and the risk entailed with removing the old one and fitting the new one. Remember..these engines were not designed to have that bearing replaced.ever!
These bearings didn't fail very often (mine is 1%) and something else caused them to fail, lack of grease and no oil or misalignment, could be an unbalanced IMS, who knows!
No matter what I do, I can't win (unless I keep the car for another 10 years and it doesn't fail and I save £700.. big deal!)

Thanks for the help anyway.Much appreciated.

If you're looking for a budget-friendly solution you could pull that bearing (since you already bought the tool) and replace it with a good quality 3204 2RS C3 (SKF or FAG, $70). You will need to source a 47mm ring clip and 3.13mm center bolt spacer to account for the new bearing being narrower without a retaining wire groove. In my opinion you can reuse the center bolt if you don't use it to pull the old bearing out (obviously it was not designed for that). You can buy an updated triple seal flange or reuse your old flange and fit a viton x-type seal for a little leak insurance.

I did all this on my car 5k miles ago and it hasn't blown up or leaked yet (Yay! One data point...). My factory dual row bearing was tight after 18 years and 65k miles, so I plan to replace it every clutch service. My opinion is that if you have a dual row, you have a maintenance item (sealed ball bearings are service items in any application). If you have a single row car, you have a design deficiency and need to upgrade your bearing to an after market dual row or plain bearing. PM me it you want to take this route and I can give you specific links to what I bought.

Well thanks for the tip but I caved in and went ahead and bought an LN dual row as well as clutch, DMF, RMS etc etc...
Ironically if I was keeping the car, and I might after all this expense, i would have left it, it was more if I was going to trade it in for a 997, much easier to sell a car that's had the IMS/RMS done together.
The tools I bought were junk, they are going back, the puller has an ID of 47 mm, the same as the OD of the bearing..impossible.
I'll do another post when I get the bearing changed.

Good move............

Replacing the bearing with just another bearing doesn't fix the underlying issue of the grease in the bearing being washed away by the engine oil.

Yes, I will be replacing,mine on a regular basis. Plan is to replace it next summer. I do my own work and won't be bashing in the new bearing. (I've seen some of those videos on YouTube).

Yes, these engines weren't designed to have the bearing replaced, but that doesn't mean that it can't be done safely.

If you don't want to replace the bearing regularly, then I believe you need to invest in a solution whereby the bearing is fed by oil (DOF, EPS, or LN Solution).

Please post when you replace the original dual row bearing, curious to see its condition.

When oil can wash away grease in the bearing, it can also lube the bearing. I know that oil can get inside the IMS hollow shaft. With fresh oil and 'thoughtful' driving (keep rev higher, avoid condensation/ fuel contaminants in oil from short distance driving without engine fully warmed up, etc.), bearing can still be reasonably lubed without grease. My thought anyway...

It's more of a design issue of the single row bearing, which may be replaced regularly... but I would not do so with the dual row bearing. Rather than spending money on bearings, my contingency would rather be a whole replacement engine.

Lots of new parts arrived today including the clutch, DMF and these...

https://serving.photos.photobox.com/...f51cb17c7c.jpg

and unboxed...

https://serving.photos.photobox.com/...6c812ca830.jpg

Thought I would fit a new thermostat while it was off and the coolant drained, went for the low temp one.

I put the new RMS in but it went from 10mm to 15mm its one slight tap so it's got to come out and a new one put in a bit more carefully this time.
Trying to find some pipe with a 56mm OD to pull the old (but perfect) IMS bearing out.
As I said before the kit I bought was rubbish, nothing worked..found out it was all from the Far East.

I ordered a new IMS tool kit from Design 911 in Essex. 2 days later it arrived, they had sent the wrong one but quickly dispatched another correct one which was the only one they stock, the EPS tool kit not LN( which the bearing is ...from them!)
They stock all the tool kits from LN but not the Retrofit one.

Anyway it appeared to me the kit had been used already which I am discussing with them now..nothing wrong with that..it just shouldn't be full price (£200).
Bearing came out easily enough, there was lots of black oil behind it but it appears to be very solid , no play at all, and quite stiff to turn. By this I mean if you hold it by the centre bolt and try to spin it, it won't. It does turn but you have to do it, it doesn't roll at all but it's smooth. The outer seal is very hard to remove, it's in very good condition.
Here it is

https://serving.photos.photobox.com/...caf3022506.jpg

You can see old grease still coming out at 11)clock position.

https://serving.photos.photobox.com/...2a1dc2c596.jpg

I am getting a RMS tool made up from plastic by the same chap who made my exhaust stud drill guides, this will ensure it's 13mm and dead square.
All these tools will be available for hire (in the UK) when I've finished this.

It's quite amazing to think that the whole IMS, chains etc are all supported at the flywheel end by that tiny centre bolt. There must be some force from the cams that the bolt has to deal with.

Looks like your original bearing is still in great shape.

So the new bearing you got feels not that tight and rolls???

New LN Retrofit is very similar although it has been in the freezer all day ready for fitting tomorrow, so the grease will be firmer, but I don't remember it spinning easily before it went in.

Today I fitted the new IMS Bearing ...yes it's done, it's in there.
I had to use a block of nylon so I could use a metal mallet to tap it in. My rubber mallet just wasn't heavy enough. That's me hitting the fitting tool , not the bearing.

https://serving.photos.photobox.com/...6594bd29ee.jpg

Then you fit the Spiro-Loc ..had to get in touch with LN as I've never seen one of these before let alone fit one. Wanted to get it right.

https://serving.photos.photobox.com/...79e4db14e2.jpg

Apparently I was the first person in 10 years to ask how to insert a Spiro-Loc.:cheers:

Then i put a small smear of silicone grease on the gasket and carefully pulled on the new flange using the 3 old bolts. Waiting for Loctite to finish that.

https://serving.photos.photobox.com/...c2985a3434.jpg

Also my RMS tool arrived today, I had my machine man make it out of nylon. It's brilliant and made fitting the RMS so easy.

https://serving.photos.photobox.com/...247447419d.jpg
https://serving.photos.photobox.com/...85bb083ec2.jpg

Btw, I removed the outer seal from my old bearing and it's perfect inside, no play or noise or anything, it's like a brand new bearing would be.

https://serving.photos.photobox.com/...6bb882524e.jpg

I would say dual row failures are most likely from poor alignment , in fact I bet the single is too but it fails quicker.
Why did I change it? Because I was there and I was spending a load of money anyway and it can be forgotten about for a while..if I was strapped for cash, after I saw it and felt it, I would have tried to replace the O ring and left it alone.
Clutch and DMF to go in next.

I love that nylon RMS tool. I made one out of pvc parts and wasn't all that thrilled with how it came out.

Yeah it's superb, t just takes all the guess work out of it.
Measuring 13mm inside he crank etc is just about impossible. This does it for you.

One thing that I found quite strange about the IMSB is the centre stud.
I'm sure you have all figured this out many years ago and it's weakness has been mentioned on this thread already but I find it hard to believe that that stud (M8) is all that is supporting the rear end of the IMS which is driving the cams.
Well I know the bearing is but that is being supported by that stud/bush and the flange is fixing the stud to the engine ( which is very secure).
I suppose by increasing the diameter of the stud you have to decrease the thickness of the flange internal busing part as there is only the same amount of space inside the bearing.

There are three major flaws in the factory center bolt:

1. There is a rather severe under cut in it to accommodate an O-ring seal; when they break, they tend to break at this undercut.
2.The material of construction, it is mild steel.
3.It needed to be larger in diameter.

Does this poorly designed factory bolt take any part of the bearing failure?

Yes. Sometimes when the bolt fails, the IMS bearing can move off axis, timing chain(s) jump, and you get piston to valve contact related failure. The IMS bearing itself is still relatively OK except for the bolt failure. Other times, the bearing itself is tearing up, possibly causing the bolt failure; so it can go either way.

Interesting... sorry one more question, this tapered bolt is common for factory dual- and single-row bearings? If so, obviously bearing design itself accounts for the failure more I guess.

Both the OEM single and dual rows use similar center bolts, but they are not exactly the same due to the bearing depth differences.

Here's a photo of the stud.

https://serving.photos.photobox.com/...d48f96a81f.jpg

You can see that the O-ring groove is the weak spot, the threaded part at the end is there to put that nut on which stops the stud coming loose from the bearing and falling into the IMS, causing all sorts of problems of which a match and a gallon of fuel word sort out nicely.

Been drilling out broken manifold studs today and re-tapping them. Dreadful job.

https://serving.photos.photobox.com/...e4bb0c4779.jpg
https://serving.photos.photobox.com/...9629c00df1.jpg

With the O ring removed it's about 8mm in the groove, 10mm either side.

https://serving.photos.photobox.com/...dfaeca539a.jpg

Thought I would post an update on my wee project.
Everything is back in, I bought some new exhaust clamps as the old ones were bad.
Very straightforward apart from a persistent leak from the new thermostat, in the end i smeared some sealant on both sides of the new gasket and that fixed it.

The main difference I noticed was how light the new clutch is, I thought i hadn't bled it correctly but it's all good , just very light to press.
Engine goes really well, revs up so easily. Since changing the new front engine mount the whole car feels much more planted, one of the easiest things to do with the best gains is to change a worn out front mount.
Really pleased and now considering keeping it (i've had it 7yrs) as I wanted a 997 but after going for a quick blast in this yesterday I reckon I'll hold on to it, there is no way a 997 is £20k more fun than this.
Just started on the front brakes, I was getting some shudder at high speeds in Germany last year, so I'm going to replace discs and pads on the front. Then it should be good for a long road trip.

Hello Troutman, great thread, read with interest, which side of Scotland are you in? I must visit the place some time, (Londoner - eww), and fish for some wild trout..

I have a few contributions to your dilemmas:

1, was the thermostat shiny clean when you refitted and it still leaked? that is a worry, was it OEM?

2, You queried how the IMSb bolt could support the side loading of the cam chains - This is now how it works - The inner face of the IMS bearing rides on the 'spider flange', that through bolt merely keeps the assembly true - i.e. stops the bearing meandering fore and aft.

3, You noted your original IMB bearing was as new once the seals were removed, but also must note it was completely devoid of the gearing grease such a bearing requires to survive when sealed by the plastic sides.. I am a fan of the seal removal & splash oil feed lubrication strategy - as you have adopted for the replacement, I would like to copy this idea on my build.

4, exhaust stud jig - what does it look like and are you willing to rent it out? You say you'll be renting out the IMSB tools also, I think I'll be a customer when the time comes also.

Looking forward to updates,

Beers!
Harry

I’ve removed three IMS bearings from my car over the last 7 years (two upgraded units) all had seals. The seals on every bearing I’ve pulled had failed and the bearings were full of oil. Removing the seal seems like a good idea. (And no there isn’t a reason to replace them this much, it’s always been a “while you’re in there” thing).

Cheers,

Harry, thanks for your comments, i'll answer as best I can.
The thermostat was from Design911 (Wahler) as are most of the bits I have bought. My engine face was very clean, the old gasket came off in one piece. Not sure why it kept leaking.
With regards to the spindle, you're absolutely right. If the bolt snapped, and it has no reason to, the spindle could in theory fall out the back into the IMS. The bearing would be still have 75% support from the flange, that's what really supports it.
I got that wrong earlier.
I was in two minds as to whether should bother with the cost of replacing the bearing, with tools it was £500 I think. I could have just pulled the grease seal off and I am very confident it would have been fine for another 100k miles especially as it was a dual row but like others have said, when you've gone to that much effort with Clutch / Flywheel / RMS etc, etc you may as well fit a new bearing. In for a penny etc...
There's no question if it was a single row.

If you go to the link below it shows the exhaust stud tools and all that with the manifold studs. They were a challenge I can tell you but all back together now and running really well, with a very light clutch.

The tools are now on ebay and I have advertised them on here too. they are £50/week for everything. £350 deposit and I return £300 when I get them back in a good state.
The RMS tool is brilliant. I can put a stud tool in as well. They do get worn if you have to do lots but they are easy to make. I can give you the email of the guy that made mine.

Anything else you want to know please ask.
BTW I have a trout farm here in Scotland...watching the Ospreys this morning going for them, amazing to see.
http://986forum.com/forums/performance-technical-chat/70662-anyone-got-cam-locking-tools.html