Overrev your M3

["Duane Collie" <drcollie@xxxxxxxxxxxxxxx>]

>From: mchiang@domain.elided (Michael Chiang)
>Subject: <E36 M3> Over-rev... have I done it?

>..and suddenly, the M3 slows considerably,  the motor screams... and 7.5+
>shows on the tach.  At least 75 shows on the speedo.  I think had almost
>let the clutch out when I caught this.

>Did I accidentally get 2nd and over revved my M3?
>
>If so... what should I do?  If I can't seem to detect any
>damage/anomalies... does that mean everything is okay??  Will/can engine
>damage occur this way?

Mike,

Yes, you over-rev'ed  your engine.  Did you damage it?  Maybe, maybe not
(probably not).  Mine has seen 7,500 rpm once as well when an *Instructor*
over-rev'ed the car at a Driver's School some time ago with no ill results
to date.

Interesting enough,  In talking to one of the BMW tuners, I've been told
that when most E36 M3 engines are torn down,  a majority show signs of
having been subjected to bent valves due to over-revving.  Apparently what
happens is that the valves can, and do get mildly bent in some instances and
the engine litterally hammers them straight again so they will continue to
run true in the valve guides.  When pulled out of the head, the valves are
burnt on the exhaust edge of the valve (they are still bent just enough so
they cannot rotate normally in the head).  A normal, unbent valve will not
have a burn area on it as it is continually rotating.  <<<<(Note that this
was relayed to me as an anecdotal story of M3 engines.  It is not written in
stone so don't carve tablets with this as a commandment and carry them down
Mt. Biwmad or send me a megabite worth of flames if you think otherwise.).

If you really do a number on your valves then your engine stops RIGHT NOW
and you're all done.  My advice, don't worry about it as there is no fix.
IF your engine is running you're essentially good to go.  Be careful when
you do high rpm shifts and consider some of the new Delrin transmission
mounts getting ready to come onto the market that will take out the
rotational torque of the transmission and help align the shifts to an easier
degree.

Duane Collie
BFKAB

------------------------------