When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My mechanic just called to tell me that my intermediate shaft bearing is failing, and that he needs to split the case to replace it. He had started to take things apart to check/replace the chain ramps and noticed unexpected material in the oil.
I know this isn't a common failure with the Mezger engine- but has anyone else had this happen?
My car is an '04 and has ~40k miles (mostly track).
GT3 or GT2? Haven't heard of the bearing failing in either but with GT2 there I've read about the IMS gear bolts backing out over time, which would require splitting the case to go in and fix. GT3 IMS gear does not have bolts so does not have this issue.
Do you trust your mechanic to be telling you the truth?
There are plenty with more knowledge in this area than me so see what they have to say.
It's an '04 GT3. My mechanic is supposed to be one of the best in the area, and I have no reason not to trust him (lots of air-cooled and race cars in his shop).
He hasn't split the case yet, so it's possible that his initial diagnosis is wrong and that something else is going on.
Actually, it does. It just doesn't fail like the ones in the M96/97 engine. Every 911 from 1964 through 2008 had an IMS bearing.
See: https://imsretrofit.com/ims-101/
Well yes...While the engine still uses an intermediate shaft to drive the camshafts, the oil pumps are driven directly by the crank. What’s more, the GT1-derived block has a different oil gallery design that ensures the IMS bearing remains lubricated at all times.
The GT3 engine does NOT have an IMS bearing. Time for a new mechanic.
interesting
Originally Posted by LIS
Actually, it does. It just doesn't fail like the ones in the M96/97 engine. Every 911 from 1964 through 2008 had an IMS bearing.
See: https://imsretrofit.com/ims-101/
-Larry
Correct.
Thanks for spreading the knowledge.
Please let us know what your mechanic finds.
He had the timing chain covers off to check/replace the ramps and found some foreign material. The IMS bearing was his guess (said he'd heard about a batch of bad bearings in the GT3), but it's only a guess until things are apart. I'm skeptical myself, but I'd rather pay for a teardown now than a new engine later.
the intermediate shaft can be seen clearly in this picture (bottom right hand corner). I don't think this is a common failure, but there is a topic on this over at Pelican . However, even though there is an intermediate shaft in a GT3 and all air cooled motors, it is a very different architecture as already stated. The bearing is probably the biggest difference as this is not a rollerbearing but the same kind of bearing as the crankshaft main bearings and has a constant oil feed i.e. the shaft runs ons a film of oil.
I am would be interested to know how your tech is able to identify this bearing as the culprit. I am assuming he found copper specs in your oil, but I think that could come from any of the main bearings. Either way, if he has found copper in your oil, you will have to tear your engine down and rebuild. It would also be good to understand the cause, as the only thing I can think of is oil starvation or a blocked oil gallery.
As Johann points out, the GT3 is a very different animal.
Here is were the bearing shells go:
And a dry fit with the IMS in place.
What, exactly did he find in the oil - which I would send a sample off to your favorite UOA place. Tell use what he finds./ These bearings always seem to wear as there is a lot of force on them in the Metzger motor (turning 4 camshafts...)...
Pictures are always good.
Remember, once your start tearing one of these down, you will be writing a BIG check...
I got an update from my mechanic. Apparently there's wear on PART of one main bearing, and minor wear on the IMS bearing. He spoke with a cup-car specialist, and apparently this kind of wear is considered normal. It's going back together now.
05-10-2021, 11:22 AM
IMS bearing... (yes, really)
