Clutches and IMS bearing

[MoscowRed]

All

Apologies for yet another call for help; I’m relatively new to the Cayman (2008 S 86,000 miles) thing and there is so much to take in.


So with all this time on my hands I have been busy, condenser replacement to name one such project. I thought I would go back through the cars mechanical history, partly to get a feel for what might need changing a when.


I came across OPC note from an inspection dated Jan 2018 (75962 miles) - oil weep from timing chain tensioner seal.


Clutch and release plate changed Jan 2014 (41097 miles) - clutch bite point is a bit high but not noticed any slippage.

1. Is the leak synonymous with a failing IMS bearing?

2. Should I change the clutch and look to replace IMS bearing at the same time?

Thanks in advance

Tob

 

[911hillclimber]

Soooo much to read on these subjects! So easy to get sucked-in on the why's and there fore's, and a lot of 'pub-talk' reasoning.

You could do worse than chatting to a reputable specialist (see Porsche Post) for advice.

1

I don't think IMS leak oil before failure and your late engine will have a good design compared to an early engine. Stand to be corrected.

2

I think the wise answer is yes, and the crank oil seal at the same time. A prospective buyer of the car will want to see the bills, who did it, and using what. As to which IMS solution is best? Hard to find out; several answers to that question.

If you use somebody to do it they will fit what they feel is a reliable solution, they don't want you to return the car, so you may not have to find a part.

 

[MoscowRed]

Many thanks - thats probably one job I won't be looking to do myself!!

Rob

 

[Motorhead]

Rob,

I think that the Porsche Centre note will refer to this known problem on the Gen1 engines and is not related to a failing IMS bearing.

https://www.porscheclubgb.com/forum/tm.aspx?m=999752

As Graham says, there's a lot of information about IMS bearing failures, etc. on the the internet, but if you want really sound information go to the Hartech site. Baz Hart is a mine of information on the subject.

https://www.hartech.org/

There were a few IMS bearing revisions on the Gen1 engine and your 2008 CS will have the last update, which I believe should be robust. However, unlike the earlier versions which are replaced easily, I think I'm right in saying that bearing replacement on your engine needs a full bottom end strip which would be expensive.

Clutch wear as always will depend upon previous usage and at 45,000 miles yours will probably need replacement in the not too distant future, but if it's not slipping and is smooth in operation I'd be inclined to leave it for the time being. A lot of garages will advise replacement of the DMF at the same time as the clutch, making it an expensive job, and it would be sensible to replace the RMS (rear main seal) at the same time.

Jeff

 

[MoscowRed]

Thanks Jeff

DMF? Dual Mass Flywheel?

I will have a look at those links over the weekend

Kind regards

Rob

 

[JohnCRS]

I think you have your answer Tob.

Preventive maintenance is good in principle, but the problem is knowing when not to do it. Signs of oil in the wrong place should always be investigated, but misting/weeping can often be best left if it is not getting worse. I would first clean the area thoroughly and then monitor.

Early warning of impending doom can be found by changing oil frequently and inspecting the filter for particles.

Clutches on these can fail at around 40,000 miles, but can last much longer. (I hope so as mine is on 45,000). Height of the pedal engagement is not a reliable indicator of clutch wear so, if there are no other signs such as untoward noises, jerks or slippage, don’t worry about it. if it does go, it will not be sudden or catastrophic, so you will have time to get it fixed.

The best preventive maintenance is to find a reliable specialist. Even if you do most of the work yourself, good advice is valuable, so a good inspection by someone you can trust will pay dividends and lower stress levels. I know, I’ve been there.

 

[MoscowRed]

Many thanks John

I like the idea of giving the area a clean first to gauge how much oil is weeping - I havent seen any patches on the garage floor so I am assuming its not too bad!

 

[Motorhead]

Thanks Jeff

DMF? Dual Mass Flywheel?

I will have a look at those links over the weekend

Kind regards

Rob

Yes, that's right Rob. It seems that DMFs are standard fitment these days on spark ignition engines as well as compression ignitions engines where they were introduced originally in an attempt to reduce idle/low speed gearbox rattle due to the significant torque fluctuations on 4-pot engines. It's questionable whether or not they're essential on an F-6 spark ignition engine, but I guess Porsche reckon there's an advantage in fitting them, although I'm of the opinion that they can introduce some light throttle low speed driveability effects (powertrain shunt).

If the DMF wasn't replaced at the last clutch change you may want to consider replacing it since it does in effect form part of the clutch assembly in that it provides the rotational cushioning effect provided by the hub springs in the centre plate of a conventional clutch.

Some wise words of advice from John, and just to mention that at a Club visit to the Cambridge Porsche Centre I recall the chief tech saying that he'd never come across an IMS bearing failure himself and that if there wasn't oil dripping from the engine bellhousing joint and only some oil misting was present, just leave it alone.

Jeff