Here is the full article
http://inwr.pca.org/LinkClick.aspx?fileticket=KksL3MCtE9s%3d&tabid=40
Starts on page 15.
Here is where it gets interesting...
Page 19 - The Boxsters;
We had 3 Boxsters, two with fairly
high mileage and one with low
mileage. All 3 of these cars are 5
chain engines.
The low mileage
car had a suspected timing chain or
IMS bearing issue. The vibration
data from the 2 higher mileage cars
looked very similar, high amplitude
combustion peaks where predicted,
fairly high amplitude Cam Chain
noise, very low Primary Chain noise
with no discernible sidebands. The
higher Cam Chain noise from these
engines is most likely normal; chain
stretch and chain guide wear, etc…
The low mileage Boxster with the
suspect timing chain or IMS bearing
issue had both a high amplitude Cam
Chain gear-mesh frequency and an
EXTREMELY high Primary Chain
gear-mesh frequency. Definitely a
chain or bearing issue; no doubts,
shut her down, get her fixed.
Conclusion page 20
Since our January 7th Saturday tech
session, the IMS bearing has been
pulled from the Boxster with the
suspected issue and sent to me.
Sure
enough, a deformed bearing cage
allowing the bearing balls to fall out
of position. Just enough additional
clearance was introduced to the
intermediate shaft that an increase
in backlash between the chain and
sprockets generated substantially
higher vibration amplitudes (makes
a lot of noise). We caught this guy
before any huge amount of metal
could be sucked into the oil and
damaged other components.
Now to contact Mark and find out where this is currently at... Stay Tuned - Rick