Canica

Clutch will be changed on my 2008 Boxster S; LN Engineering apparently suggests, for MY 2008 engines, to remove the IMS bearing seal so it can be lubricated by engine oil. Do you think this is a good idea, or would it be best to leave it alone if it has not presented any problem? I would be very grateful for your help.


Best,

P-on

I anxiously await responses to this one.

chronarion

There's a few tradeoffs here. Based on what I've read about the IMS failures, IMS failure stems from insufficient lubrication of the bearings. In turbo variants, the bearings are force lubricated by a direct oil feed.

The bearing seal holds in some permanent bearing grease. Reportedly the seal does not hold under heat, and as a result engine oil gets in anyway, and tends to flush out the permanent grease. With the seal there, you just get some old engine oil there trapped over time that breaks down and gets worse. Removing the seal allows engine oil to recirculate and replenish.

So it comes down to:

- Were you lucky enough that somehow your bearing seal held? Will it still hold? Chances are it'll break down someday.

Presumably after opening it you'll know Are they able to get to it easily? If so you may as well retrofit at that point.

Sapientoni

The facts are the IMSB is half submerged in oil when the level is kept full or near it. Yes, oil seeps in and eventually replaces the oil. I've taken 3 of these engines apart, or at least the IMSB and the IM shaft always contains oil, as does the bearing. The seals retain the proper amount to lube the *****. I strongly suspect many of the earlier model garage queens that had imsb failure also had infrequent oil checks. Those cars were recommended oil changes at 20,000 miles I think. For sure the factory put a million miles on their test mules, but checked the oil at every tank of fuel or other tank at least. Who has a garage queen and does that? The 2006-8 IMSB is good for at least 145,000 miles with nothing but oil kept properly leveled. I'd suggest if you want to do "something" loosen the nut that holds the stub shaft, and turn the stub shaft 180°. This will present a new running surface to the inner race where the most pressure is. It could also double the life of the bearing. Look up my posts here and elsewhere. I usually add pics to prove/support my advice, but am not on my computer. The pic of Boilerinspector's fail showed the inner race worn out on half the surface, but like new on the other half.
Best of luck and don't worry about the IMSB in this model Porsche.

Canica

Thanks to both for the advise! Best!

P-on

I like this answer for two reasons. It makes me feel better about my 49,000 mile well maintained 987 and it echoes what a Porsche dealer told me, which was that they've seen very few 987's with problems if properly maintained.

Sapientoni

It is assumed you will do the RMS, but I wanted to mention it. The cost of flywheel bolts and the extra maintenance are well spent in this case. Assuming the mechanic is experienced with these engines, I just want to add that some heat releases the fixing compound on the nut, you must turn the nut and not the shaft when loosening. Always use new loctite on the nut when putting it back.

Canica

Thanks for the replies and advice. Please excuse my ignorance, but what is an RMS? Do flywheel bolts have to be changed for new ones when changing the clutch? My mechanic is a master Porsche mechanic working in a very reputable dealership. One of his colleagues has stated he has changed the IMS bearing without engine disassembly; do you think this is possible? Would you do it?


Best,

Georound

There are a couple of types of IMS. Single row and double row. One can be pulled out of the block easily and the other is now pulled after some metal from the cases is removed. Basically, a retaining flange is machined away so the cases don't need to be split. RMS is rear main seal, in case you have an oil leak. Preventative maintenance if replacing the clutch. Nearly all the labor has already been done.
Also, most would agree that the failure rate of IMS is low (single digit). However, failure may result in catastrophic failure of the engine. Plenty of used engines for reasonable price now though.
RMS, no doubt, should be replaced if getting new clutch.

Canica

Thanks Georound! I will make sure the RMS is replaced. Is there anything else you would do while-you-are-at -it. My engine has 14500 miles on the clock and was installed on July 2009. As mentioned on my other post, I have just bought the car and want to start ownership with as much of a right foot as possible. Cuurent to do's include new clutch, wind deflector, front rotors, glovebox, tires, repair a minor oil leak, draining, flush and re-fill of the cooling system, change of gearbox oil, change of power steering fluid, change of engine oil and filter, change of air and cabin filters, change of sparkplugs, change of alternator and water pump belt, change of brake fluid, inspection of all water drains, wheel alignment, draining and re-filling the headlight/ wiper wash system and installation of USB/ iPod port. As for the IMS bearing, I feel inclined to just let it be given it has not given any problems, unless any of you would strongly recommend to take of the seal and/or rotate the shaft as suggested above. Thanks for all the help!!


Best,

Georound

Edit: just reread your other post and your PPI uncovered some issues.

Alternators are not known to go out. I would use that money for belt and waterpump. Keep in the box until needed. Change the coolant when/if the pump starts seeping. Plugs should be just fine in a low mileage engine. Porsche OEM plugs are 4x the cost of rebranded plugs. Coils crack with age and heat, but aren't that fragile.
A bit of blue smoke at startup is normal. Too much or consistent puff and Air and Oil separator failure is likely. There is a rubber diaphragm that cracks.

Fluids, tires, brakes, filters, belt....sounds like you have it covered.

Canica

Thanks Georound!

Canica

For the cooling change; would you use tap water? Distilled water? Does it matter? Thanks!!


Best,

Sapientoni

I have changed 3 IMSB's in 2006 3.4 987.1 engines. It can be done with engine in the vehicle, but it requires my modification, or the other peoples. I think mine is best. Requires a new flange which I've designed to my specs. For sure I use a better seal than the other guys round O-ring.
Always use distilled water to mix with the antifreeze, just for the extra tiny bit of performance. Less erosion of aluminum parts from electrolysis.

The RMS (rear main seal) requires taking off the flywheel and the factory recommends new bolts. They are cheaper than finding out it was an expensive mistake to not change them.

Best of luck.

Canica

Thank you so much for the advise!! Best,