the Porsche 986/996 IMS bearing "issue"

[lemming]

in case anyone has been following the Jalopnik "cheapest Porsche ever" buying guide or the subsequent "best Porsche under 30,000USD" thread, this may or may not be of interest.

I have not personally come across any vehicles that have suffered an IMS bearing failure --but i have run across many cars that have pre-emptively replaced the part as both insurance as well as to prop up resale value.

the issue is that the intermediate shaft which runs north/south through the engine pan, whereas in the past was anchored by an "open" rotating bearing (ball bearings) that swam in a sea of oil, in the M96 motors, they changed it to a closed bearing design (who knows why). this means that if the seal which holds the grease in that self-contained bearing fails, the bearings lose lubrication and the bearing fails. pretty straightforward. the bearing failure tends to show up early --or-- on cars that are not driven often. Early means some OEM related failure (rare). Late failure can be attributed to low miles and cars sitting (not driven) or infrequent oil changes --if the oil is dirty, at some level when contaminated with fuel and whatnot, it will accelerate degradation of the seals on the bearing. Overall fail rate tracks closely with years (2000 to 2002 being apparently the worst) with an overall fail rate of maybe <5%?

long story short, I have my not superbly maintained car (with 50,000 city miles) on it serviced. the IMS bearing was fine. naturally, having the tranny dropped to put in a new clutch, it would be obtuse to not checkout the IMS bearing, so that's what happened. if anything, the OEM dual mass flywheel was in bad shape and needed immediate replacement.

my advice? don't worry so much if you are driving the car. look at the IMS bearing (if your car has over 30,000miles) as a wear and tear item that piggyback's onto the labor costs of a new clutch.

the really scary things are the water pump (overheating potential), the air oil separator (AOS), the crappy ass OEM flywheel, of the radiator plumbing.

i'll post pictures tomorrow. i have all of the original parts held for me. i'm not thrilled about the out of pocket, but I negotiated intensely so overall, I feel that for a one owner car, I did okay.

[Jeff_DML]

Thanks for the writeup. As I mentioned in a previous thread my cousin wants to buy a 996 so this is of interest.

Is it normal for a 996 clutch to be going out at 50k or was the previous owner just a shitty driver?

[lemming]

Originally Posted by Jeff_DML

Thanks for the writeup. As I mentioned in a previous thread my cousin wants to buy a 996 so this of interest.

Is it normal for a 996 clutch to be going out at 50k or was the previous owner just a shitty driver?

cannot really comment on that, other than the 911s are not designed to be stop and go traffic cars.

it fouls up the spark plugs (carbon on DFI engines) and the clutch is designed (on my C4S) to be the weak point, to protect the transmission.

it would appear that my car was mostly city driven. the clutch wear was light (i was being pro-active). it's the shitty ass flywheel (which has always been true for Porsche). for some reason, they also elect to use a LUK dual mass flywheel that disintegrates easily. in the G body era, it was catastrophic when it failed. in the modern era, it's just expensive to replace the stupid thing.

[lemming]

Originally Posted by Jeff_DML

Thanks for the writeup. As I mentioned in a previous thread my cousin wants to buy a 996 so this is of interest.

Is it normal for a 996 clutch to be going out at 50k or was the previous owner just a shitty driver?

the simplest and easiest thing to do is to factor a clutch (and IMS bearing) into the purchase price.

so you basically subtract that from whatever the asking price is.

I did that and got that chunk subtracted and then some, which is why i still feel like i'm slightly ahead (for the moment). subject to change and constantly humbled by what i don't know, but you know. for now.

[Jeff_DML]

Originally Posted by lemming

the simplest and easiest thing to do is to factor a clutch (and IMS bearing) into the purchase price.

so you basically subtract that from whatever the asking price is.

I did that and got that chunk subtracted and then some, which is why i still feel like i'm slightly ahead (for the moment). subject to change and constantly humbled by what i don't know, but you know. for now.

so what is rough cost of replace clutch and IMS bearing?

thanks

[lemming]

Originally Posted by Jeff_DML

so what is rough cost of replace clutch and IMS bearing?

thanks

<$3000.

it's not even specialty work even more. it's very standard. like 6hours of labor, plus parts. most seem to drive home for about $2500?

clutch is $500-$700? IMS bearing is like $800. and the rest is labor and if the flywheel is toast or not ($800-$900).

every Porsche mechanic worth their weight could do this in their sleep now because everyone has it done as preventative maintenance.

[lemming]

http://www.pelicanparts.com/catalog/...ion-Clutch.htm

and here:

http://www.pelicanparts.com/catalog/...UPG996_pg3.htm

most shops order from Pelican anyway. so the costs are usually within reason.

[Jeff_DML]

thanks

[lemming]

Anyway. Not an issue for me and my car was "enthusiastically" driven for 50,000mi