[Shotimes] Cancer with a twist

[Mark D. Mallory]

For those interested in crank cancer, here is a new form that I have not yet
heard of.  Typically the timing sprocket works its way loose, which
eventually wears on the woodruff key, which in turn lets the timing sprocket
move more, so and so forth.  This situation is compounded by a leaking water
pump which allows things to rust and wear away faster.

I just stripped down the front of my engine (or at least tried to) to
replace a leaking water pump.  Had a heck of a time breaking the crank bolt
free.  I thought it was kind of odd that the bolt would stop the starter
from turning the engine.  At this time I had the battery hooked up with
jumper cables, so I figured I wasn't getting enough juice to the starter.
This is something I have not had a problem with in the past.  Hooked the
battery up directly to the cables in the car, turned the engine over, and
presto I heard the bolt break free!  Or so I thought.  Turns out the bolt
sheared itself at the beginning of the threads.  Not good!

Pulled the crank dampener off and half the woodruff key fell out.  Yes,
that's right, only half the key fell out.  The key had sheared directly
between the pulley and timing sprocket.  The part under the dampener had
about 1/3 of it's width worn away.  Did I mention that I could turn the
dampener through ~1/4" without moving the crankshaft?

Anyway, after further investigation here's what I suspect happened.  The
crankshaft bolt must have worked loose allowing the dampener to move
(similar to crank cancer scenario described above).  I've had a leaking
water pump (apparently for longer than I should have).  I'm guessing that
there was an abnormal amount of wear taking place, since there was red rust
on the crankshaft, woodruff key, and inner surfaces of the timing gear and
dampener.  At some point the woodruff key sheared in two, probably from
excessive vibration due to the crank bolt being loose.  From this time
forward the crank dampener was free to "rock" back and forth on the woodruff
key during acceleration and deceleration.  My best guess on why the bolt
sheared is that it rusted in place.  I have yet to confirm this.  Lucky for
me the woodruff key sheared... there is no apparent wear on the timing
sprocket or the keyway under the sprocket.

Some may ask if the bolt was cross threaded.  My response would be, I don't
think so.  I don't recall if that bolt was removed when I had my tranny,
clutch, and motor mounts done last.  Can anyone tell me if the dampener
needs to be removed to install motor mounts?  If it does need to be removed
than I have some questions for the mechanic.

Shortly after that service was done, I experienced a shimmy in the front end
(only upon acceleration) that I thought was coming from the inner cv-joint
on the driver's side.  Never was able to isolate the shimmy... until now.
I'd be willing to bet that the shimmy was in fact the crank dampener gett'n
it's groove on.  Chalk that one up to inexperience... the thought that it
could be a loose dampener never crossed my mind.

Of coarse now, I'm waiting for a crankshaft bolt and woodruff key (found
using PartsVoice).   Then I get to try and remove what's left of the bolt
from the shaft.  To do this I've decided on drilling out the bolt and
re-tapping the hole.  With any luck I won't mess anything up... wish me
luck!  I've decided against messing with easy-outs, since the risk of
breaking it is just too great.

Well that's my story for now... I'll keep everyone posted.

Mark Mallory
Toledo, Ohio
'95 SHO MTX... broken :(