Could it be Crank Cancer?...was: Re: [Shotimes] Rod Knock or Tensioner Slap?

[George Fourchy]

On Tue, 11 Nov 2003 22:50:57 -0500, Leigh Smith wrote:

>Doesn't do it when cold. Only when warm.
>Sounds a little like a rod knock, but very light, not like any rod knock 
>I ever heard.

It's been a while since we've had crank cancer.  Is it time for another case?

That is hammering on (and wearing of) the crank (actually the woodruff key IN the
crank) by the crankshaft sprocket for the timing belt.  It's caused by improper (or
failure of) tightening of the crank damper bolt.  It's one of the two or three weak
links in this engine (this, bearings, and oil pump).  It's not noticeable when cold,
but is steady when warm....it usually makes one sound per rev of the crankshaft,
which would make a similar sound to one rod going out.  It's most noticeable at
idle, but is audible up to about 3K rpm, at which point other engine noise covers it
up.  It will get worse over time as the wear increases, and at the same time engine
performance diminishes as the cams get retarded.  It starts out as a very quiet
thump, barely audible, but over a period of 3 or 4 K miles will become quite
noticeable.  A mechanic's stethescope will not locate the sound until you put it in
the center of the (concave) damper bolt head while the engine is idling.  

That's how I found mine, after over a year of listening to it get worse and worse.

George